Cyclecomputer and GPS accuracy

New page about the history of distance and speed measurement on bicycles, and the limitations of accuracy in measurement. Did you know that GPS readings wander, so you can rack up some distance even if you are standing still?

Raw GPS readings don't quite follow the road.

Raw GPS readings don’t quite follow the road.

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Cyclecomputer database

Our pages of cyclecomputer instructions have now been brought completely up to date, with links to user manuals for almost every make and model, including GPS. These pages are a unique resource.

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Additions to the Gear Calculator

New crank lengths have been added to the Gear Calculator and Internal Gear Calculator, so they can calculate gain ratios for children’s bicycles with cranks down to 100 mm (less than 4 inches).

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More hubs in cable-pull cribsheet

Added information on four hubs to the internal-gear hub cable pull cribsheet:

Shimano Alfine 11-speed
SRAM G9
Sturmey-Archer S3X
Sturmey-Archer ASC

Thanks to Jeff Meredith and Michael Wilson for the measurements!

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Measuring tricks

Testing a cotterless crank with a wrench

Testing a cotterless crank with a wrench

We have a new article on how to perform the precise measurements needed to determine whether bicycle parts fit each other, without expensive and fragile tools. There are a number of clever tricks — for example, you can test the width of the square taper of a cotterless¬† crank with an ordinary open-end wrench!

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Reorganization of headset tables

headset

top headset

Our tables of headset sizes have been reorganized to make it easier to determine which headset can be made to fit which frame and fork. Fork crown race seats can be milled down and head tube race seats can be enlarged. The tables now are in order of head tube race seat size, as the frame is the more difficult and expensive to replace, followed by fork crown race seat size. The tables are used in the article on headsets  and several other articles.

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Shimano 4-speed hub gears

Shimano Nexus 4-speed coaster-brake hub

Shimano Nexus 4-speed coaster-brake hub

Expanded coverage of Shimano Nexus 4-speed hub gears — we now have rebuilding information, translated from manuals in German which are the only ones we could find online — complete instructions for both the freewheeling/Rollerbrake version and the coaster brake version. Thanks go to Patricia Morris for assistance with translation.

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Shimmy, or speed wobble

A new article on shimmy, or speed wobble — what it is, why it happens, how to prevent it and how to recover from it.

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More tire-sizing updates

Four "650" tire sizes -- photo thansk to Aaron Goss of Aaron's Bke Repair.

Four “650” tire sizes — photo thanks to Aaron Goss of Aaron’s Bicycle Repair.

http://sheldonbrown.com/650b.html : added more info on “27 five” tires, and a photo (thanks to Aaron Goss!).

http://sheldonbrown.com/tire-sizing.html : added several tire sizes

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Sheldonbrown.com’s angle on the Trek quick-release recall

Sheldonbrown.com’s angle on the Trek quick-release recall. This addresses technical issues which we haven’t seen covered in news reports.

An assortment of quick-releases showing how far they open

An assortment of quick-releases showing how far they open

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