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Personal Drive Train Strategy 2024 #47   BackToList   Print
Written: 2024.06.13   Review Date:2024.06.13    LastUpdate: 2024.06.20

1. Preface
2. Purpose of Bike
3. Type of Drive Train
4. Intro to Components
5. Cranksets and Bottom brackets
6. Cassettes and Wheel Hubs
7. Chain Length
8. Nine Speeds
9. Tools
10. Spare Parts
11. Conversion and Upgrade Cases

1. Preface
This document describes my personal strategy for ending up with my low cost touring/utility bikes. The basic idea is to convert existing bikes so they have low gears and inexpensive components. Thus this involves changing drive train components: cassettes, chains and cranks. What I want is readily available parts. This drive train is based on readily available mountain bike parts fitted onto available touring bikes. To get the low gears on a "gravel bike", you usually have to change the model of crankset. My preferred crankset these days is a standard 42/32/22 triple crankset, costing 79.00. My standard cassette is the Shimano 11-34 cassette, costing about $35.00. Basically,what I'm doing is putting so called "mountain bike" components onto a touring bike.

What you end up with is a bike that is cheap enough you don't mind leaving it locked up outside. And which has low enough gears to handle heavy loads uphill. And which the drive train components can be readily replaced every couple of years if necessary.

When converting to smaller chainrings, or larger cassettes, you sometimes have to change the derailleur or the bottom bracket. I have come to the conclusion that it is good to work together with a local bike store with a good mechanic. On the most recent crank conversion I did on my old Miyata, I had to change the crankset, the bottom bracket and the derailleur. This was quickly possible working with my favorite local bikestore "Bike Doctor" because they had all the sizes and types on hand. Once I had the new crank, we had to quickly try several different bottom brackets and derailleurs. So that is why it was handy to do it with the bike store, rather than struggle with trying to source the parts online.
 I found it too difficult to try and figure out what goes with what all from the published specs regarding chain lines, Q Factors. There are too many other parameters such as fender clearance, frame clearance, etc. to spell out with the specs.

If buying a new gravel bike, you'll want to convert to low gearing, check that the bottom bracket shell is the standard thread-in type 68mm. This is discussed in a separate chapter.

This document finishes with a chapter with detailed "case studies" of actual bikes I have maintained over decades. Some new bike owners think that a viable strategy is to just keep replacing parts with the same part number as they wear out. This is only good when the bike is really current. It also doesn't allow for strategic upgrades to get lower gears, or less expensive parts. When maintaining bikes over decades, you'll always be using new and different models of the key drive train parts.

2. Purpose of Bike
This document is limited to talking about what I call "utility touring" bikes. Or "destination" bikes. These are bikes that are relatively low cost both to buy and maintain. A thief would have a hard time selling any of my bikes for more than $1000.00. They have the following features:

  1. Low gears, such that you can tour up relentless hills, with the bike loaded
  2. Driven in rough weather, sometimes off pavement
  3. Standard easily available Parts
  4. Not so valuable you can't leave it locked up for several hours at the park, or shopping

I'm not talking about a poorly maintained "clunker" or a one speed bike. The bike should still be fun to take on long tours, and be running perfectly. My satisfaction comes from thinking about how well it is running, and my knowledge of how everything works, and how to adjust and maintain it. Like a fighter jet, the biggest part of my investment is in all the tools and spare parts and knowledge, not in the actual bike. So only a small fraction of my investment can be stolen.

Such "utility touring" bikes will be heavier than a lightweight road bike. It's not the ideal bike if your primary goal is to go on short fast rides with a bike club. For that, you would want a lightweight carbon frame, no carrier or fenders, thin tires, and specialized parts.

At the same time, my "utility touring" bikes are not really what you want for mountain bike trails. I'm not talking about downhill bikes with suspension.

In the chapter on case studies, you'll see that most of the bikes have steel frames and friction shifting. Only one of them has disk brakes, the rest are rim brakes. But you don't have to end up with the same thing I have. To implement my strategy, when looking at a bike you might buy, there are two main interfaces to make sure you understand:

  1. The crank interface (BB shell type)
  2. The rear wheel interface (dropout width, or Thru axle

For the crank interface, the most standard is the BSA 68mm shell, into which you can fit a square taper BB and crank, or Hollowtech 2 piece crank, etc. Another crank interface is the T47 which I am investigating.

For the rear wheel, the most standard is the 135 mm dropout with a 10mm axle. That determines what rear wheels you can put, and thus what cassettes. As long as the interface is standard, and you have friction shifting, you can always change what cassettes you are using.

Myself, I'm into steel, but you can base a good touring bike on an aluminium frame. I'm into 8 speed cassettes. What is essential is that it can use low cost consumables - cranks, cassettes, chains, and wheels. And you get something you can do all the adjustments and routine maintenance yourself.

3. Type of Drive Train
The most important single standard is the way the crank fits into the frame. And second is the way the rear wheel fits into the frame. The most standard way cranks fit into the frame for the past 40 years is the threaded bottom bracket - 68 mm wide and with the so called "English" thread specification of BC1.37 x 24 threads per inch. These have been the standard for 40 years. A wide variety of bottom bracket setups will screw into this type of shell.

Once you have standardized the shell, the most standard crank spindle is the "square taper". The crank arms are pulled onto the tapered ends of the spindle by a substantial bolt threading into each end of the spindle. To remove the crank arms requires a standard crank puller. There are dozens of Youtube videos showing this.

  1. BB Shell:
     The standard 68mm shell is not limited to having a square taper spindle. Some bikes come with other types of crank that still screw into these shells. For example Shimano Hollowtech which is a hollow axle with a two piece crank. The thing to stay away from for low cost are various proprietary "press fit" cranks, wider non standard shells, and all the strange bottom brackets. As long as your frame has a 68mm threaded shell, you can always convert to standard square taper if your more exotic crank needs replacing.

  2. Crankset
     For any given square taper crankset, you will need the proper length of crank spindle. These days the crank spindle comes as part of a sealed bearing unit called the "Bottom bracket". A typical part number is Shimano BB UN300, costing about 24.00. These "bottom bracket" units specify the shell width and the spindle length:The current Shimano model is the BB UN300. On the package, it specifies 68mm and the spindle width:

      [ ] 117
      [x] 122.5
      [ ] 127


  3. Dropout Width:
     The thing you want is a standard width "dropout" into which the rear wheel slips. In the 1980's the standard was 126mm, then it went to 130mm, and 135 for mountain bikes. If you are looking at a bike before 1990, you may encounter 126mm dropouts, these require a bit more adapting as on 2 of my bikes described here. Some new bikes have 142 dropouts and a "thru axle" instead of the standard quick release. Thru axles are not standard threads, and every manufacturer is different. However, that won't cause you problems replacing cassettes.

  4. Shifters:
     The simplest shifting system to maintain is one where the rider simply moves the shift lever the correct distance. The shift lever is held in place by friction. Thus this system is called "friction shift". The other system is "indexed shifting", where the shifter has a ratchet that moves the cable the proper distance each shift. These are now much more common on new bikes, but they require more adjustment. And they are limited to whatever number of sprockets they were designed for. A 10 speed shifter moves each gear less distance than an 8 speed. So you can't just switch to a cheaper cassette without also buying another shifter. Because of this, many heavy duty touring bikes use friction shifting. Originally drop bar shift levers were on the down tube, but nowdays touring bikes usually have them on the end of the handlebars.

     With all my bikes I have friction shifting, not indexed shifting. Unfortunately most new bikes, except specially built touring bikes have indexed shifting. With friction shifting, you can use any wheel and gear arrangement without change. With index shifting, you tend to have to stick with the same number of speeds - if you started with a 11 speed cassette, you can't just switch to a much cheaper 8 speed cassette. Whereas on my old Miyata, I simply replaced the old 5 speed freewheel system with a modern 8 speed cassette wheel.

  5. Deraileurs:
     Both front and back derailleurs have to roughly match the size of gears you have. If you switch the front crankset down from 50 teeth to 42 teeth, you will need to lower the derailleur, and perhaps get a new one. The cost of the current Shimano front derailleur is 28.00. Same thing on the rear: If you are replacing a typical road bike cassette such as 11-28 with 11-34, make sure you have a long cage rear derailleur. See the separate chapter on derailleurs.

  6. New Bikes:
     For new bikes, a typical model is the Felt Broam 60 which is a 2x8 bike available with mechanical disk brake. They are at Bike Doctor for $1529.00. It has the standard 68mm bottom bracket. It comes with the typical 46/32 road crankset, and a 11-34 cassette. So to get a low gear bike, you need to convert the front crankset and bottom bracket it to a Mountain bike 36/22. I presume the parts to do this are around $100.00. If you had to also switch the derailleur, that would be another $30.00. I assume it would take them an hour to make this change.

    Difference between this bike and my bikes:

      Aluminium frame
      Disk Brakes
      Indexed shifting
      Rear thru axle
      Tubeless tires
      142 mm dropout not 135 or 130

    Supposedly according to bike radar, road bikes have a 68mm shell and mountain bikes use a 73mm. However I measure my 1993 Rocky Mountain bike to have 68mm.

4. Intro to Components
What I'm talking about is the kind of drive train you want for a touring or commuting bike driven sometimes in bad weather, sometimes on dirt roads, sometimes loaded, and often on steep hills. You don't need 10 or 11 speed cassettes. An 8 speed cassette is cheaper and just as durable. For our purposes, what you want is that triple crankset (for lower gears) and only a 8 speed (for cost minimization). Some more expensive touring bikes have 9 speed cassettes, which have the advantage of slightly lower gears (11-36 rather than the 11-34 limit of 8 speed cassettes. They had to allow the 36 teeth to have acceptable gears with only 2 chain rings. But those cassettes are about $50.00 instead of 30.00, and take a slightly more expensive chain.

For the ultimate low gear standard drive train, you want a 3x8 setup: 42/32/22 on the front, and 11-34 on the back. That gives you a low gear ratio of 22/34 = 0.64. It is important to understand that expensive components don't outlast the low cost 3x8 drive train. In fact, the lower cost cranks are steel whereas the more expensive are aluminium alloy. Steel is harder than aluminium. And the expensive 10 and 11 speed chains must be thinner than the common 8 speed chain.

Usually any heavily used drive train requires periodic replacement of chains, cassettes, and crank rings. In the past, the chain rings were sold separately from the crank, but now days the individual rings are hard to find, and often more than an entire new crankset, so a strategy of replacing the individual rings costs more.


  35.00 Rear Cassette
  80.00 Crankset (usually sold as a unit including crank arms, and chain rings
  24.00 Bottom Bracket (The sealed bearing unit, square taper
  28.00 Front Derailleur
  30.00 Rear Derailleur
  5.00 Shift Cables

 Few new bikes come with the ideal low cost drive train. They usually come with gears that are too high, and often expensive designer aluminium chainrings. These will wear out just as fast as lower cost steel rings. In all the cases I'm describing, the bike frame has the standard 68mm threaded bottom bracket shell.

So there are two discussions: (1) Routine Replacement (2) Conversion or Upgrade

You can usually do the maintenance yourself. Just buy similar parts and install them. All you need is a few special tools like a crank puller, BB puller, chain whips, chain cutter and a cassette puller. The most common annual maintenance requires replacement of the chain and rear cassette. The cassette you want is the Standard 11-34 cassette which costs about 30.00. The 34 tooth cassette is the largest size available for the standard 7-8 speed bike. Slightly more common are the 11-32 tooth cassettes.

  Conversion: To convert to different components, such as significantly lower gears, I have found it is best to do it in conjunction with a good mechanic. Ideally you can work with the mechanic, and understand what decisions he is making. Make sure you understand what they are doing.


5. Cranksets and Bottom brackets
This chapter explains how Cranksets attach onto the crank spindle, and how the crank spindle and bearings are threaded into the frame.

Originally cranksets were sold to take replaceable chain rings. Which chain rings was determined by the "bold circle" of your crank arm. However these days, separate rings are expensive and rarely stocked by your local bike store. So nowdays the kind of cranks I'm talking about are sold as a unit, including both the crank arms and chain rings. The only part number that is separate is the so called "bottom bracket" which is the sealed bearing and crank spindle. The bottom bracket threads into the frame. Once it is installed, the cranks are pressed onto the ends of the axle spindle by tightening a hex bolt. Now we can discuss the two main interfaces: The Bottom bracket to frame, and the crank to spindle.

  1. Bottom Bracket To Frame:
     The term "bottom bracket" refers to both the "shell" on the frame and also the sealed bearing unit you thread into it.The crank bearings and axle thread into the frame. Fortunately this thread is standard across all the bikes we are talking about. When you are replacing the "bottom bracket" nowdays you are talking about a sealed unit such as Shimano BB UN300. It contains the bearings and the crank spindle. You thread it into the drive side with a special 20 spline "Bottom Bracket Tool such as the Park Tools BBT-22. There are many Youtube videos.

    usually refers to the sealed bearing unit that contains the bearings and the crank axle "spindle". threads into the frame. Fortunately most commuter bikes the threads
     The most common interface between bottom bracket and frame is the 68mm threaded "shell". The "bottom bracket" is the sealed bearing unit which contains the spindle and the bearings. The most common Shimano bottom bracket unit is the UN300. All these bottom brackets come with a variety of spindle lengths (117-121-127mm). The spindle length is necessary to interface with a given crankset.

  2. Crankset to Bottom Bracket:
     (Crank to Spindle) The crank spindle is part of the "bottom bracket". The end of the spindle is a square taper, such that when the crank arm is forced onto the taper by a hex bolt it is forced to spread and becomes wedged tightly on the spindle. This has been the system since 1980. It is still the standard on most hybrid and commuter bikes.

  3. Crank Arm to Pedal:
     The pedals thread into the ends of the crank arm. Fortunately this thread is standard. Over the years, pedals often develop clicking problems and need replacement. For this you need a long 15mm wrench, and they are often stiff.

  4. Crankset and Chain Rings
     Originally many bikes came with fancy aluminium cranksets and the standard practice was to replace individual chain rings. This required knowing the "bolt circle" of the crank. However the replacement rings have become more expensive and rarely stocked by your local bike store. So nowdays it is much more common to simply replace the entire crankset when an individual ring is worn out. The rest are probably worn too. In addition, this gives you the opportunity to go for lower gears. The cranksets I recommend are now steel and cost about $80.00.

  5. Chainline Crankset to Derailleur
     If you are replacing a crankset with a different model you must ensure that the chain rings end up with the same offset from the frame as before. Otherwise your chain line won't be optimal, and your front derailleur won't reach.

    The offset of the rings is determined by both the crankset design and the bottom bracket spindle length. If different, you will need a different bottom bracket. For a given crankset, there is no one spindle length that is suitable for all bikes. On my Miyata, I originally had a 127 spindle. The new crankset was normally recommended to go with a 122 spindle. But with the 122 spindle, the chain wheels were still too far away from the frame, such that the derailleur would not reach. So we had to put in a 117mm bottom bracket. Fortunately I eventually was working with an experienced mechanic at Bike Doctor who had all the parts on hand.

  6. Height of Derailleur vs Frame
     If you are changing to smaller chain rings, such as 50/40/28 to a 42/32/22, you will have to lower the derailleur so it is the correct distance above the chain. (Usually about 1 cm above the frame) But then with an old derailleur, you can run into problems where the old cage is too long, and not the right curvature. So the best thing is to change the derailleur, costing about 30.00.

    There are two things that can vary with a derailleur: the "swing" and the "pull".

    The "pull" refers to the direction the cable comes from. Top pull means that the cable comes from the top, whereas bottom pull means the cable comes from the bottom. My road bikes all have bottom pull, but the mountain bikes (Rocky Mountain and Brodie) have top pull.

    The "swing" refers to the position of the pivot in relation to the clamp. Top swing (low clamp) means the derailleur pivots above the clamp. (the swing is on top). Bottom swing "Downswing" ( means the clamp is above the derailleur. With the Miyata conversion, we knew we had to change the derailleur when converting the 50/40/28 tooth to the smaller 42/32/22. The original derailleur was the wrong curvature, and could not be lowered without snagging the frame stay. So my mechanic initially tried a top swing derailleur, but that had problems, so he switched to a bottom swing model. (Altus FD M313-6)

6. Cassettes and Wheel Hubs
There are two things that you have to discuss when talking about changing wheels or cassettes:
  1. If changing wheels, the dropout width
  2. If changing number of cogs on cassette, the freehub width
  3. If changing number of teeth on largest cog, the derailleur "capacity"

The wheel hub and axle have to slide into the "dropout" on the frame. The dropout may be 126mm, 130mm, 135mm or wider. This must be the distance between the locknuts on the axle of the wheel.


  1. Dropout Width:
     The modern standard on road bikes and Hybrid bikes is that the frame has a "dropout" width of 130mm. That is the distance between the outside edges of the locknuts on the axle. The axle itself will be somewhat longer, in order to fit into the slot on the frame. Eg: The axle on the new wheel I put onto the Miyata is about 140mm.

    The standard changed from 126mm to 130mm about 1992. With an older frame, you have two options:
      1. Get the frame "spread" (bent) so it is permanently 130mm.
      2. Remove spacer washers on the axle such that you end up reducing the wheel width

    With my bikes, I have done both. The Norco, I got a local old timer shop to spread the frame for me. With the Miyata, I was able to remove spacers such that it fit easily into the 126 dropout.

    There is a certain amount of tolerance in the Frame and hub spacing. It's only 4mm you are dealing with if you've got wheel with a road bike hub. Even without any adjustment, you can usually push a wider wheel into the frame, although it is harder than with a perfect fit.

    Sheldon Brown discusses the subject under Bicycle Frame/Hub Spacing.

  2. Freehub Width
     The most standard Shimano freehubs are designed to take either 8 speed cassettes or 9 speed. The 9 speed cassette is the same width as the 8 speed, the cogs are just thinner, and the chain is thinner. That is the reason 9 speeds require a thinner chain.

  3. Rear Derailleur Capacity
     The "capacity" of a derailleur is it's ability to take up the slack as the chain goes over different sized cogs. Eg: Going from 42 on the front to 22 on the front, the rear derailleur has to take up the slack. A "long cage" derailleur can take up more slack than a short cage. In my bikes, I've had to switch the rear derailleurs when converting to mountain bike gears.

    The maximum slack is going from largest and largest to smallest and smallest. The derailleur must have the "capacity" of that difference. Eg: Compare the largest on the front (42 teeth) and the largest on the back (34 teeth) with the smallest on both front and back (22 on front and 11 on back:

      42+34= 76 links
      22+11= 33
      Diff 43 Capacity required
    The rear derailleur usually are capacity 45 teeth.

    Note that the chain only goes half way around the cog, so the slack when shifting down from a 34 tooth cog to 30 is only 2 links. However I think the "capacity" difference is said to be 4.


7. Chain Length
When altering the size of either the cassette or the front chain rings, the chain will have to be a different length. For example when you convert from 50/40/28 front to 42/32/22 front, you will have to remove half that many links. You can determine the number of links to remove either by the "largest cog" method, or by the formula method. Both are below:

  1. Largest Cog
     The length of chain can be determined by putting the chain around the largest cog on both front and back and adding one or two links. So if you are changing your largest front ring from say 50 to 42, that is 8 teeth less, so for the half circle, you would remove 4 links from your existing chain.

  2. Formula in inches
     If you are not sure your current chain is correct, you can always just measure the distance and take into account the half circle of the cogs on either end. It makes sense to work in inches rather than links because you can use a tape measure. The standard bike chain has 1/2 inch per link. So if we measure everything in inches we would multiply by 2. To get the inches around the cogs, you divide by 2x2=4. The first 2 because there are 2 links per inch. The second 2 because the chain only has to go half way around the cog. So a 42 tooth cog needs 21 links, which are 10.5" long.

    Here's the Formula

      - measure the distance from center of crank to center of back axle. eg: 17.5 x 2 = 35"
      - divide the number of teeth on largest chain ring by 4. eg: 42/4 = 10.5
      - divide the number of teeth on the largest cassette cog by 4 eg: 34/4 = 8.5
      total: 54 inches = 108 links

    Usually you add 1 extra link just so you are not at the limit. So what we want is 109 links.

    A typical new chain is 114 links, so you cut off 5 links.

8. Nine Speeds
The cheapest cassettes and chains are 8 speed system. The 9 speed uses a more expensive chain. However, the Shimano 9 speed system has the possibility of a 11-36 cassette, , whereas the largest 8 speed cassette is 11-34 teeth. The reason they had to allow 36 speed is to support the trend of only having 2 chain rings instead of three. (Called 2x instead of 3x). Bikes with only 2 chain rings usually don't have as low a gear as the triple, although if you sacrifice the high gear, some mountain bikes go down to 22 teeth.

Both 8 and 9 speed fit on the same freehub, so you always have the option to switch back to an 8 speed. This is easiest if you have friction shifters, but it is possible some 9 speed shifters will accommodate a missing speed.

On a 9 speed, the chain is thinner. It does not have a master link like the 8 speed, instead you need a special single use master link. This is not good if you intend to remove the chain regularly for cleaning.

Another option is 2x rather than 3x. The 2x system can give you almost as low a gear, with 36/22 as compared with 42/32/22 on a triple.

9. Tools
As I have explained earlier, a big fraction of my investment in bikes is in tools and spare parts. I have a database that has a picture of each tool. I use this to keep track of what each tool is for. Some of my tools were only useful on past configurations of my bikes, so I won't list them here. Below are some of the most used tools for my current configuration of bikes:

  1. Cable and Housing Cutter CN-10C
     Park Tool Professional cable & housing cutter) (To cut new brake cable housing if replacing cables). Without this tool it is difficult to avoid crimping the cable housing.

  2. Cable cutter CN2
     Gives a nice clean cut of cable. Used regularly. Trying to cut cables with regular plyers often

    10. Spare Parts
    A big part of my strategy is to have spare parts for almost every component that is known to need replacement. So I have spare cassettes, chains, cranks, bottom brackets, disk brake calipers, and cross pull brakes. With standard generic parts, this does not cost this much. It's part of my "jet fighter" strategy.

      1. Parts are "in stock"
     2. Experiment how it goes together
     3. Experiment with different models
     4. Diagnosis by swapping

    1. Parts in Stock
       By ordering the parts in advance, your bike never goes "out of service" waiting for parts. For example, we have often discovered that brake pads are worn out. What you want is to always have some on hand, so you can immediately install them when it becomes apparent the old ones are worn out.

    2. Better Prices
       Part prices fluctuate. By buying in advance, you can get things cheaper. Things like disk brake pads are much much cheaper when ordered from Amazon. For example, we just ordered a set of 4 pairs of disk brake pads from Amazon for 18.00, yet all that is available at our local stores are resin pads $38.00 each pair, and out of stock.

    3. Parts for Experiment
       If I even have a brand new and complete spare rear wheel for my Rocky Mountain. The benefits of this strategy are:

    Summary of cost of Inventory
      Chains: 4 12.00 48.0


    1. Disk brake Pads
       Betsy's Opus Legato is fitted with standard Avid BB7 disk calipers. Like all disk brakes, you eventually have to replace the pads, and you often don't know until the brakes become hard to adjust. A common symptom is that the brake lever pulls in way too far, and when you try to adjust the clearance the wheel rubs. So we removed the old pads, and noticed the spring was bent, and the pads were worn out. So we were able to reach into my parts drawer and immediately install new pads. Then it was time to replenish my parts supply. First I checked the local stores. They were out of stock. So I went to Amazon. There I found about a dozen different offerings, and vastly different prices. One type was $18.00 for four pairs, which is about 5.00 per pair. Yet the resin ones I had recently bought at West Point had cost 38.00 for one pair. So I ordered the 18.00 ones, and we'll see how they are. As it turned out, a few days later they arrived, and shortly after, the original spring failed on the previous ones. So we popped in the new ones and they have worked for 100 km so far, so I assume they are ok. I'm a big supporter of local stores, but I think their business strategy has to be to have every possible standard spare part on hand. Otherwise I will have my own inventory, sourced at Amazon.

    2. Spare V Brakes
       (Shimano BR-T4000) For some reason, the standard Shimano V Brakes seem to fail after a couple of years. A common problem is the levers don't return. Sometimes The springs wear out, sometimes it's the cables. In any event, we always have both front and rear V brake units on hand. They cost 31.99. As I write this, I check MEC and they are out of stock. Can't find them at Bike Doctor. At West Point they are now 32.99. But the reason for having them is for quick debugging. We've had several cases where we aren't sure if the problem is the brake unit, the cable or the lever. The quick answer is to swap in a new brake, and see if the problem goes away. So cost of a couple spares is 31.00 times 2=62.00

    3. Spare Avid BB9 Unit
       Maintaining and adjusting and finding problems with disk brakes can be challenging. So part of my reason for this is to be able to familiarize myself with exactly how to install the brake pads. I will always have access to the spare, whereas Betsy may have the actual bike in use. It will be a lot easier to have a separate unit on hand for me to fiddle with when we are discussing what could be the problem. And then having a spare unit means we can immediately swap in the spare unit.

    4. Spare Disk Rotors
       Eventually disk rotors wear out. But even before, we have sometimes suspected a slight warp in the rotor when the wheel seems to be rubbing slightly. Having a spare, we can just swap it in. Also, there is a huge difference in price of rotors. As I write, I see two rotors at Bike Doctor website for 54.99. The cheaper one 37.99 is not available. On Amazon are about a dozen 6 bolt rotors 160mm diameter. Prices are from 12.99 to 43.48. So I ordered a couple of the cheap ones, and will examine them in detail. I notice the cheap 12.99 ones give the actual dimensions. Rotor Size:The Disc Rotor inner diameter 44mm, outer diameter 160mm, thickness 2mm, each weights 110g. I suspect the expensive ones may be marginally better for high performance uses which are irrelevant to our fleet. But I will find out.

    5. Spare Wheel
       I have a brand new spare 26" rear wheel for my Rocky Mountain. For that wheel, I have a brand new 8 speed and 7 speed cassette. This allows me to quickly refresh in my mind how to remove the cassette with the chain whips. As you may know, removing a cassette usually requires the use of the chain whip, and involves considerable force. Sometimes I wonder which direction I should apply the huge forces required. But with my spare wheel, I can easily review the procedure without huge forces.

    6. Bottom Bracket Bearing Units
       I have 5 sealed bearing bottom brackets in stock. All are for the standard 68mm frame shell but different lengths of spindle. The purpose of some is spare parts. Most are brand new, But one is a BB which was suspected of causing a problem, but later cleared of suspicion. One is the Shimano Hollowtech type, which I have used to remind myself of how Hollowtech works, since one of our bikes has this type of 2 piece crank.

    7. Spare Crank
       Since low cost cranks only cost 79.00 and since the chainrings regularly wear out, I may as well stock a spare. This can also be used to diagnose drive train problems such as creaking crank/bottom bracket mysteries.

    8. Spare Cassettes
       I have about ten spare cassettes for 7, 8 speed and 9 speed drive trains. One reason is to make sure I have spare parts. Some freehubs will only take 7 speed, and to use 7 speed on an 8-9-10 freehub I have the spacers. Having cassettes in inventory allows me to buy them when available. For a long time it was hard to get 34 tooth, so I had 32 tooth cassettes. Having spares is useful for debugging. I had one problem with my Rocky Mountain where for some reason, the shifting didn't work properly. I couldn't figure out which component was responsible, but having spares allowed me to quickly swap out the cassette to see if the problem went away.

    9. Spare Chains
       Chain prices seem to vary, and I have a half dozen spare chains. Last week there were KMC 9 speed chains on sale for 10.00 at MEC, yet my other Shimano 9 speed chain cost 44.00. So I have one of each. I've never been able to detect a problem with the less expensive chains. Probably the most important thing about chain life is cleaning them. Oily chains pick up grit which wears down the bushings. This is the reason I use wax based lubricant rather than oil, supposedly it picks up less grit, and the chain is certainly easier to handle.

    10. Spare Pedals
       Over the years, I've encountered many cases to suspect pedals when trying to find noise problems. So obviously it is handy to have one brand new pair on hand for debugging. However it is often difficult to tell which pedal is causing the problem. So you don't just want to throw away the suspects, at least one is probably good. Often the pedals were not the problem after all, it was the bottom bracket or crank. Or the pedal problem only appears after hard use. So I have a system of keeping track of the old "suspect" pedals. I engrave a ID number on each pedal and keep records. Somehow I end up with a dozen pedals, all of which were suspect at one time, but many seem OK later.

    11. Conversion and Upgrade Cases
    This chapter describes various conversions and upgrades I have done on actual bikes. There is a lot of wisdom buried in these stories, and I know no other way to communicate it. My strategy has always been based on standards, but as you will see, I've had my share of non standard stuff I had to deal with. I keep repair journals for each bike and I used these to get the facts.

    From these records I am able to document the drive train evolution, and the typical trial and error involved in long term bike maintenance. The subject of this document is restricted to maintenance of drive trains. Over the 30 year life of the bikes, it has been necessary to convert to new model components. My goal in conversions is usually to go to more durable, lower cost components, and to lower gearing. Most common was to replace chains and cassettes. As I selected cassettes for lower gears, this sometimes required a new rear derailleur. Eventually most of the bikes also wore out the center ring on the crankset, which required either a replacement center ring, or a low cost replacement of the entire crankset.

    In doing many of the conversions it is necessary to gather specific model information from professional mechanics in local bike stores. I have come to the conclusion that any big conversion such as cranksets it pays to be working with a professional mechanic at a bike store with a good supply of on hand parts.

    1. Miyata 1000
       This bike was top of the line in 1986 and came with a fancy aluminium Sugino AT 50-40-28. crankset. It was the first bike with a triple chain ring. On the rear was a thread on freewheel, 5 speed 14-30 teeth. The frame dropout width is the standard 126mm. In the first few years I mostly just replaced chains and freewheels, without any improvements.

       - 2016: Bottom Bracket Upgrade
       The original bottom bracket axle was the old type where the spindle is separate from the ball bearings. However, it eventually wore out, so I upgraded to the modern sealed bottom bracket system. The standard bottom bracket was a Shimano UN55. These come in a variety of standard shell width and spindle lengths. All of my bikes are 68 mm width. And for this bottom bracket, I used a 127mm spindle.
       - 2023: Freewheel to Cassette:
       The original rear wheel was a 40 spoke with a thread-on freewheel. The freewheel was a 5 speed. The dropout width is 126mm. In order to use modern cassettes, I had to replace the wheel. The challenge was that the standard frames nowdays have a 130mm dropout width. Thus a modern wheel would have an axle that was 4mm longer. The ideal solution would be to find someone who could "spread" the frame to 130mm, like was done on my Norco. But the local shops I use don't do that anymore. However my notes say that by removing washer spacers I was able to fit the modern wheel.

      Once I had a modern wheel, I installed a 8 speed 11-32 cassette. The first cassette was an 8 sp 11-32 (Shimano CS-HG51). That gave me a slightly lower gear - 32 teeth instead of 30 on the old freewheel.

       - 2024: Chain and Cassette:
       The next conversion was in 2024. The chain tool indicated the chain was stretched and should be replaced. Sometimes I ignore the gauge and run the chain-cassette combination till it actually starts to skip. But in this case, I decided to change the cassette and chain together to get the lower gear. So I replaced both chain and cassette. But once I replaced the chain and cassette it turned out that the center crank ring skipped badly with the new chain. This is very common. I decided to get a new crank similar to the conversion I had done myself on my Rocky Mountain. A new crankset would have steel rings which should last longer than aluminium alloy. Also I could get lower gears at the same time - 42-32-22 So I set about to do the conversion myself.

      But the model of crank I had bought for the Rocky Mountain was no longer made. I researched and it seemed the Shimano FC M361 (Acera) was the replacement. So I phoned around, West Point did not have a solution, but both Bike Doctor and MEC had such cranksets in stock. I gradually accumulated knowledge from the phone conversations. It seemed the normal bottom bracket was BB UN300 with a 122.5 mm spindle. The previous conversion I had installed a UN55, but this model was replaced with the UN300. The only place that had a UN300 122.5 mm spindle was MEC. So I bought 2 of them at 24.00 each.

      So then at home, Betsy and I unthreaded the old bottom bracket. We first tried from the drive side, but the tool engagement was too shallow. Finally we tried the non drive side, where the tool had a better grip. We also used an old pipe to extend the arm on the tool. It came right out, and then the drive side was easy too.

      I then installed the bottom bracket. On the non drive side is an aluminium ring, coated with threadlock. I put it in fairly tight, but it still showed some of the threads, but I was reluctant to really reef it. On the drive side everything looked normal except I couldn't get the derailleur to shift to the largest cog. The chainrings were too far out away from the frame. I examined the original crank and now noted it had a big indent, such that the chainrings were offset toward the frame. So I thought I needed a similar crank. I rode it back to Bike Doctor, wheeled my bike into the shop and asked for Tom Pardo, who I had talked with the day before. I had already noted his name from the day before, it's always important to keep track of valuable names.

      So Tom and I discussed the differences in the crank. No such crank was available, but he came up with the idea of using a shorter bottom bracket spindle. Fortunately he had one, a UN300 117 mm spindle instead of the 122mm. It solved the problem. He also noticed that I hadn't reefed in the bearing cap on the non drive side. He had a big torque wrench and he reefed it in all the way. But once we lowered my existing derailleur, it's cage was getting snagged on the chain stay. So he suggested we try another derailleur. So he quickly installed a compact "top swing" derailleur. But then then problem was snagging the fender. So we quickly switched to a newer model of bottom swing derailleur, (Altus FD-M313-6.) This was more similar to my original and worked perfectly.

      So I left the store and came to the conclusion that for any such upgrade, it pays to work with a store and a good mechanic. There is no way I could have predicted all those problems by studying online specs or talking over the phone.

    2. Norco 12 Speed
       This is a typical drop handlebar "ten speed" bike sold in the 1970's and early 1980's. The gearing was 52/40 on the front and a six speed 14/26 freewheel on the rear. I bought two of these bikes used in 1988 for about $150 each so I'd have parts. Like all bikes of this era, the bottom bracket was not a sealed unit. Instead it consisted of three parts: the spindle, two bearing cups, and about 11 ball bearings on each side. This is still the system in this bike, I would only have to replace it if I upgraded the front chain ring. The brakes, derailleurs, cranks were all from the Shimano 600 group, one step below Dura-ace. The Shimano 600 crankset is a 52/40, with a built in "one key" self extracting bolts. The crank can be extracted with a regular 6 mm allen key. I used this feature on my 1991 trip back to New Brunswick and Nova Scotia where I was able to take apart the bike into pieces small enough to be accepted as regular baggage on the airplane, and on the bus.

      The first conversion I did on this bike was to replace the original rear wheel with one that had a "freehub" rather than the old thread-on freewheel. The freehub system at the time used Shimano "Uniglide" system, in which the individual cogs could be swapped. I rode the bike about 18 km to work each day, and used to experiment with different combinations of cogs. I was also able to replace just the worn out cogs, rather than buying a whole cassette. In these years, when I wore thru the rims on my wheels I used to also just replace the rim when worn out, rather than the whole wheel.

      But by 2013 it was cheaper and faster to just replace entire wheel. So I bought a generic 700c wheel complete with hub for less than 100.00. Nowdays wheels come with the freehub already installed, and so I converted to using 7 speed hyperglide cassettes. "Hyperglide" cassettes are different from Uniglide, and require prebuilt "cassettes" rather than being able to buy individual cogs. So I standardized on 7 speed CS-HG50 cassettes on all my bikes. The 7 speed freehub is slightly narrower than the ones intended for 8/9 speed cassettes. Nowdays, the 8 speed is the standard, and a 7 speed cassette requires a 4.5mm spacer.

      Dropout Width: The most important thing in wheel replacement on older bikes is the dropout width. The original dropout width of all 7 cog cassettes was 126mm, but 8 speed cassettes they switched to 130mm. This was about 1992. The dropout width for "road bikes" has stayed at 130mm since the 1990's, but mountain bikes went to a wider 135mm dropout and even wider. Because the Norco was originally 126 mm, I had my local bike shop "Ace Cycle" to "spread" the frame to 130mm. From then on, that bike will take standard 130mm wheel.

      Rear Derailleur: When I converted to the 13/34 cassette, I had to switch the derailleur to a long cage design.

    3. Rocky Mountain Hammer
       I bought this bike brand new in 1993, to be more suitable for backroad trips than our previous 700c touring bikes. It has straight bars, 26" wheels and a rigid non suspension fork, similar to today's hybrid bikes. It is now my main "city commuting bike".

      The original drive train featured a polished aluminium 48-38-28 crankset and a 13-30 seven speed cassette.

      The first major conversion was in 2010. The fancy aluminium crankset was worn out, so I opted to convert to the standard Shimano Acera steel crankset, costing only 49.00, and with lower gears. It also featured a chain guard ring, which has proved to be very useful for preventing pants from going into the drive train. Since 2010, the steel crankset has lasted very well, as I have replaced multiple cassettes and chains while still retaining the same crankset chain rings.

    4. Brodie Quantum Mountain bike
       This bike was bought brand new in 2000 for about $750.00. It has solid front forks, still common at the time for mountain bikes. It has 26" wheels and came with 8 speed 11-34 cassette. It still has the original aluminium crankset is 42/32/22. This bike is driven year round for commuting, and has been used on extensive tours such as around Iceland, across Europe, etc. In 2015, the sealed bearing bottom bracket was replaced by West Point Cycles. Chain and cassette replacement in 2015,2016,2018,1019,2023. The entire rear wheel was replaced in 2023. In 2016, the center ring was replaced for 49.00 as part of a drive train overhaul. In 2024, the chain and cassette are needing replacment, and perhaps center ring. If so, it may be advisable to convert to a low cost steel crankset.


    5. Opus Legato
       This is a drop handlebar 9 speed steel touring bike. It was custom built with standard touring components. It has standard 700c wheels with mechanical disk brakes, bar end friction shifters and a triple 48/38/28 crankset and a 9 speed 11/34 Shimano XT cassette. These 9 speed cassettes are about $59.00. The chains are about 50% more than an 8 speed. The next upgrade on this bike will be to convert from 34 teeth to 36 teeth cassettes, which are only available with 9 speeds.