What's new at sheldonbrown.com
The Gear Calculator has now been upgraded to allow entry of data from a rollout measurement. When you enter rim diameter and tire width, the calculator will automatically give you a rollout number, but you may edit the number to reflect your bicycle’s tire pressure, weight load and tread depth.
We have upgraded and updated the Gear Calculator. Main improvements:
An example of results:
Enjoy!
Our gear-graph article now includes a new, much improved version by Jeremy Mak of the diagram which plots gear ratios of bicycle cassettes and freewheels. His version uses Javascript so you can create a plot for any tooth counts.
On our page https://sheldonbrown.com/flats.html, we now have a slo-mo video of a bicycle riding over a cattle guard, showing how the tire can compress almost all the way to the rim without damage.
Reader Howard Phillips has provided some updates on repair services. And we continue with our step-by-step instructions on DIY matching good leather from one saddle with an undercarriage from another.
Thanks to John Thurston, we have a PDF of how to overhaul the Sachs 3×7 hybrid-gearing hub. Most parts of this hub are the same as the H3015 hub, the version without a coaster brake in the T3 series.
Updates — Harriet and I have been updating articles and fixing dead links. Latest is our article on mixing and matching drivetrain components, where we fixed the link to the important, deleted Art’s Cyclery page on derailer, shifter and cassette compatibility, and made other updates. We are making heavy use of the Internet Archive, which preserves pages that have been lost to link rot — so you don’t have to search for them yourself. We support the archive with donations, and you also should.
An idler is a freewheeling sprocket that can take a bicycle chain around a corner, or adjust chain slack. Derailer pulleys are the most common example. In a chain run which is driving or braking, something more robust is needed. We discuss idler type and location, and how to convert a bicycle freewheel into a robust idler.
Electric cars are too quiet. Bicyclists need to hear them coming, and ShelBroCo has solutions that appeal to the frustrated Tesla driver. Catch our unbeatable deal before tariffs force us to raise prices!
(Best experience with a phone is with it held horizontally).
