Bicycle rims and tyre widths

Preamble

A friend of mine was wondering whether they could put narrower tyres on their racer’s rims, in order to gain a speed advantage. Conversely, I was wondering if I could put fatter tyres on my racer’s rims in order to stop falling into cracks in the roads of Bangkok.

Whilst I am sure that I have written about this before, I can’t find the article so I may be repeating myself here…

Continue reading Bicycle rims and tyre widths

Swapping a freehub for a cassette hub

Preamble

Leading on from 7 speed dilemas, I decided to swap the hubs myself and finally get around to learning how to build a wheel. Basically I’ll be taking out the freehub from a new cheap Chinese wheel and swapping it with a Shimano FH-RM50… However, nothing is as simple as it seems… especially when the Chinese rim and lacing differs considerably (and confusingly) from that described by Sheldon Brown….

Continue reading Swapping a freehub for a cassette hub

7 speed dilemas

Preamble

If you already have a freewheel hub with a 7 speed freewheel gears (i.e. MF-TZ07) using an IG or HG (hyperglide) chain, this chain will only work for 6,7 or 8 speed gear sets. Any higher and the chain will not sit correctly on the narrower pitched gears… see Bicycle chain – width:

  • 6 speed – 7.3 mm (932 in) (Shimano HG), 7.1 mm (932 in) (SRAM, Shimano IG)
  • 7 speed – 7.3 mm (932 in) (Shimano HG), 7.1 mm (932 in) (SRAM, Shimano IG)
  • 8 speed – 7.3 mm (932 in) (Shimano HG), 7.1 mm (932 in) (SRAM, Shimano IG)

Shimano uses the same chain types on 6, 7,and 8 speed designs.

So if you need to switch wheels to one using a cassette, and you want to retain the existing chain, then you will need a HG gear cassette, as a CNXXXX will not fit the chain. So a Shimano CS-HG20 7-Speed Cassette (13-23T) would do the job. Note that a spacer may also be required.

Also ensure that the hub/cassette is hyperglide (or compatible).

Continue reading 7 speed dilemas