Update to Bolt Circle Diameter Cribsheet

We have reviewed the bolt circle diameter cribsheet, checked bolt-hole spacings using trigonometry and made some corrections. Apparently, the spacings were measured rather than calculated based on angles — and measurement is never exact! We have also added entries for several new patterns. Some of the new ones with uneven spacings had to be reverse-engineered from photos and, though we think that we have them right, we welcome feedback.

Measuring bolt-circle diameter

Measuring two holes away, right side to right side (or left side to left side) gives the most accurate result with a 5-bolt chainring.

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Osman Isvan on Hills, Winds — and Data

Osman Isvan takes a deeper look into hills and winds.

  • Do you (or should you) work harder when climbing a hill?
  • How hard do you (or should you) work on a given hill? Does it depend on your gearing? The slope of the hill? What are all the relevant factors?
  • Do you (or should you) work harder against an uphill slope than you would work against a headwind? Why?

Hill and Wind factors in Osman’s effort

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Osman Isvan on Ride Data

Osman analyzes data from over 1000 of his own bicycle rides to see what they show, and describes what might be discovered by mining the huge troves of data held by Strava, RidewithGPS and other GPS-based mapping services. Osman makes a particularly trenchant suggestion for e-bike design based on his analysis, and discusses issues of data privacy. Find this along with Osman’s other articles at  https://www.sheldonbrown.com/isvan.html

Figure 1 from Osman's article

Figure 1 from Osman’s article


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Taping Handlebars

Sheldon left his article about taping handlebars incomplete. It is completed now, all you might ever want to know and maybe more! https://sheldonbrown.com/handlebar-tape.html

Taping past a Torpedo shifter

Taping past a Torpedo shifter

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No joke

It is traditional for sheldonbrown.com to post an April Fool’s day page, but this year we couldn’t think of one that wasn’t either frivolous or, if it addresses the present situation, dark humor and potentially offensive to people who have lost friends. We do have this:

No joke

Sheldon Brown alone on his Moulton, September, 1971.

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Selling Bicycles and Components

We have expanded our article for individuals selling bicycles and components — which also holds advice for buyers. There is a new section about shipping. This article holds all the basic information you need on where to post an advertisement and how to create it — how to take good photos of the bicycle, and measurements so the buyer will be able to determine whether the bicycle fits.

Measuring seat-tube length

Measuring seat-tube length -top

Measuring set tube length,starts at the center of the BB spindle

Measuring set tube length starts at the center of the BB spindle

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Synchronizing Audio and Video

Sheldonbrown.com technical writer and editor John Allen frequently shoots video from his bicycle using more than one camera; sometimes a separate audio recorder. The output must be synchronized in post production. John has now performed a major update on his article about how to keep the recordings in sync, going so far as creating true surround sound without a surround recorder.

Hand clap to synchronize video and audio

Change speed dialog box in the Audacity audio editor.

Change Speed dialog box in the Audacity audio editor.

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Braking News

We have updated our page about the different types of bicycle brakes, which added descriptions and several photos illustrating the different types.


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Additions to cranks page

John has added quite a bit of text to the cranks page; more about crank length, and an entirely new section on how to check for several kinds of damage; also several illustrations where there were none before.

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Gear calculator updated

The Gear Calculator has been updated with new Shimano, SRAM and Campagnolo cassettes, and the new Shimano Steps 5-speed internal-gear hub for E-bikes. French and German versions of the Calculator have been updated too.

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