We publish another paper by Osman Isvan. He uses a simplified model with only 3 degrees of freedom and simulates system frequency response under steady-state and transient conditions. He investigates the effects on vibration isolation of several key parameters including tire pressure, frame compliance and riding position. The graph below from his paper, one of several, shows results when tire pressure is changed.
Graph from Osman Isvan’s paper on bicycle dynamics
A few months ago, a reader prompted us to make some updates to our chainwheel bolt circle cribsheet. But now we have followed up on that effort, greatly expanding our coverage, and we have added a set of templates which allow you quickly to identify the bolt circle of alnost every model of chainring, and the tooth count, without the need to measure or count by hand. It’s all here: https://sheldonbrown.com/cribsheet-bcd.html. Example template is at the right.
If you can correct any inaccurate information or you can identify a chainring that we do not cover, please let us know. We are not too proud to take corrections, and we’ll even credit you on the site for your contribution!
New article about the GoPro Hero5 Session action camera, latest in our series of articles about shooting video from a bicycle. This is a very small and light camera which will not weigh down a helmet and is especially good for use on a drone. It has some advantages and disadvantages worth knowing about.Note: the photo may be larger than life size! The camera is about 1 1/4 inches on a side.
GoPro Hero 5 Session action camera
Older smartphone no longer maps bicycle routes well? Rides are recorded as 173,000 hours long? (Really!) New article by our friend Mark Sevier explains these problems and offers some solutions.
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 two holes away, right side to right side (or left side to left side) gives the most accurate result with a 5-bolt chainring.
Osman Isvan takes a deeper look into hills and winds.
Hill and Wind factors in Osman’s effort
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
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
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:
Sheldon Brown alone on his Moulton, September, 1971.
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 -top
Measuring seat tube length starts at the center of the BB spindle
