My personal strategy for ending up with my low cost touring/utility bikes
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.
If you need to change the crankset to get lower gears, you may need to change the derailer. Eg: Typical road bikes had 50 tooth large chainring. To change to the standard 42/32/22 chainring requires moving the derailer down on the seat tube. You may have to buy a new derailer, in which case the clamp diameter must be able to fit your seat tube. Some derailers come with extra spacers such that they will fit more than one seat tube outer diameter. ost commonly, these derailleurs now come in a 34.9mm diameter, with shims included to fit smaller 31.8 and 28.6mm-diameter seat tubes.
[ ] 117
[x] 122.5
[ ] 127
The other thing that often changes when you change crankset is the length of bottom bracket spindle. eg: My old Sugino road crankset had a different "indent", and thus the bottom bracket spindle length had to be shorter, otherwise the derailer could not reach the outer chain ring.
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 less expensive 8 speed cassette. Whereas on my old Miyata, I simply replaced the old 5 speed freewheel system with a modern 8 speed cassette wheel.
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.
COMPONENTS
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
NEW BIKES
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.
MAINTENANCE
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.
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.
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.
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.
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.
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:
The rear derailleur usually are capacity 45 teeth.
42+34= 76 links
22+11= 33
----
Diff 43 Capacity required
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:
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:
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
Summary of cost of Inventory
Chains: 4 12.00 48.0
REASONS FOR SPECIFIC SPARE PARTS
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.
- 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.
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.
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.