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Historical Changes to Standards #14   BackToList   Print
Written: 2020.05.26   Review Date:2020.05.26    LastUpdate: 2020.05.26

1. Historical Changes to Standards

1. Historical Changes to Standards
Overall trends: Below are big changes which span all the types of bike.

  1. Rear Dropouts from 126 to 135 (2000)
     Original ten speeds and touring bikes had a 126mm dropout on the rear frame. With the advent of the mountain bike in 1990's, the standard became 135 mm. It is hard to get a replacement wheel for 126 inch dropouts. such a bike. I explored various options with my Miyata 1000, both stretching the frame wider, or various wheel strategies, but none were acceptable. With 135mm dropouts, you can easily use any 700c wheel.

  2. Cassette rather than Freewheel 1990
     Original ten speeds had 126 dropouts and a screw on freewheel. With the advent of the mountain bike, Shimano developed the modern cassette system, now used on all bikes. With the cassette system, you buy the whole cog set as a unit and slip it onto the "free hub" which is sold with the wheel. A typical 8 cog cassette costs $35.00. The Shimano cassette gears shift much easier than the old freewheel cogs. The cassettes were designed to work with indexed shifting, but work perfectly well with friction shifting.

  3. Indexed shifting 1990
     Original ten speeds had the shift levers on the down tube of the frame. You just moved the lever the right distance and it stayed in position by friction. To shift, you had to develop a feel for moving the lever the right distance to go up exactly one cog. This was easy to do, and it was also easy to shift 2 or 3 gears at once. It was very simple to replace cables as they were short and all external. Later, the shift levers were moved up onto the handlebars, but were still friction shift. However, when Shimano took over with the cassette system, they standardized the distances between cogs such that shifters could be "indexed". With indexed shifting, each click moves you up exactly the right distance for the next gear. However such a system is trickier to adjust, and also means that the shifter is inherently only suitable for a certain number of cogs. So you can't easily replace a 9 cog cassette with a less expensive 8 cog cassette.

  4. Wheel Size
     Original ten speeds had 27" wheels. In the 1980's, the standard became 700c all over the world which was slightly smaller. This size is still the main size today. The proper name for this size is BSD 622 which means 622 mm diameter where the bead of the tire sits in the rim. In the 1990's mountain bikes came out with 26" wheels (BSD 559). This was the standard mountain bike size till about 2015, at which time, the manufacturers started pushing two sizes: 27 1/2 (BSD 584) and what they call "29ers". A 29er is really just the same size rim as the old 700c wheels, BSD 622.

  5. Brakes
     Original ten speeds in 1970's had caliper brakes that bolted on with a single bolt above the wheel. If perfectly adjusted and in the dry they work fine. This is still the most common brake on racing bikes. But the problems were: they don't work well when wet, (2)are hard to adjust with fenders, (3) Won't accommodate large tires. So by the mid 1980, touring bikes and then mountain bikes went to cantilever brakes, which pivot from permanent brazeons on the forks and frame. The next advance was about 2000, when the V brake was developed. About the same time, Disk brakes started to appear. Disk brakes have the advantage of not wearing out your wheel rims, so you don't need new wheels. I discuss all the different types of brakes in the Brakes chapter.

  6. Aluminum Frames (2000)
     From 1970 to about 2000, the vast majority of frames were steel frames on both racing bikes, touring bikes, and mountain bikes. The better ones had chrome moly steel tubing. During those years, there were a few bikes like Cannondale that had aluminum frames, but you paid a premium for the aluminum. Aluminum tube allows frames to be much stiffer because you can make the tubes a bigger diameter for the same weight. About 2000, the whole industry flipped over to primarily aluminum frames. However for touring, a chrome moly frame gives a softer ride, less stiff, and so touring bikes tend to have chrome moly frames. But now you pay a premium for chrome moly.

  7. New "provisional" standards
     Starting about year 2010, many new bike models started to introduce new "standards". These standards are not yet stable, but you'll see them on lots of new bikes.
     - Thru Axle hubs rather than quick release (for disc brake bikes)
     - wider hub spacing both front and back
     - thicker diameter axles (12mm instead of the standard 9 or 10
     - wider bottom brackets
     - bigger diameter bottom brackets
     - press fit BB instead of the 68mm standard