Drivetrain for road bike - going round in circles.

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theclaud
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Joined: 14 Nov 2007, 3:09pm
Location: Swansea

Drivetrain for road bike - going round in circles.

Post by theclaud »

No pun intended.

Looking for advice please, from people who know about road bikes.

I am a mountain biker/commuter-on-a-mountain bike, but a friend very kindly gave me a road bike frame and quite a few usable components, and I'm delighted at the prospect of joining the skinny-wheels-and-scared-of-potholes brigade. I've got to get some more stuff to finish the build, and don't know what to get.

I bought (perhaps hastily) some Shimano tiagra wheels, which take an 8 or 9-speed cassette, and I have some downtube shifters that seem to be 7-speed. I have a rear mech that I think is meant for 8-speed systems, and an old but unused front mech. I had thought initially that I'd just buy some new shifters and a new rear mech, and run a 9-speed cassette and a double chainring. Then I saw the price of this stuff and decided to rethink. So I just want to get it running with however-many-gears for as little money as possible. If I use spacers can I put a 7-speed cassette on the wheel? Is it worth spending lots for 9-speed components instead? This is further complicated by the fact that I don't know a lot about gear ratios etc for road bikes, so don't really know what I need...

Sorry if it's rambling and confused. Any advice appreciated!
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Si
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Post by Si »

If I use spacers can I put a 7-speed cassette on the wheel?


Yes. The 8spd mech will be fine with it too (use a 7 or 8spd chain).
This assumes that you want to use it indexed, if you are happy with friction then you could have a 9spd cassette and chain.

As for buying replacement further 9spd specific stuff - ask a 1000 cyclists and you'll get 1000 different answers. OK, so two really.
Personally I am happy with 7spd and see no need to go 9spd (some will say that 7spd parts are hard to get - I've not had this problem yet).
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theclaud
Posts: 40
Joined: 14 Nov 2007, 3:09pm
Location: Swansea

Post by theclaud »

Si wrote:
If I use spacers can I put a 7-speed cassette on the wheel?


Yes. The 8spd mech will be fine with it too (use a 7 or 8spd chain).


Great. Thanks Si.

I think I will do that. Seems a shame to turn my nose up at the FREE components I was given, and if seasoned roadies are happy with 7 speeds, I don't see why I shouldn't be...
thirdcrank
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Joined: 9 Jan 2007, 2:44pm

Post by thirdcrank »

Shimano compatibility

The link is to Sheldon Brown's 'Drivetrain' article. This gives you chapter and verse on backward/ forward compatibility for Shimano cassette systems. There is quite a lot to plough through but your OP raises quite a lot of issues.
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