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…
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….
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 (9⁄32 in) (Shimano HG), 7.1 mm (9⁄32 in) (SRAM, Shimano IG)
7 speed – 7.3 mm (9⁄32 in) (Shimano HG), 7.1 mm (9⁄32 in) (SRAM, Shimano IG)
8 speed – 7.3 mm (9⁄32 in) (Shimano HG), 7.1 mm (9⁄32 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).
The rear suspension of my MTB has four spacers, which go around the shock mounting bolts, two on each end of the shock, one either side, between the frame and the shock mount holes. All but one has cracked and snapped.