vernon levy wrote:
> I have a road bike with a Sora group set. The rear derraileur is a
> long arm one and I have triple chain ring at the front. The rear
> cassette is an eight speed close-ish ratio 12-23 road cassette. I'd
> like to lower the gearing but the only cassettes that will do the job
> appear to be mountain bike ones e.g. 11 - 28. Will the change be
> /that/ noticeable? Will the wider ratio spacing cause problems.
Should be able to get that working, but there will be more occasions of
not being able to select a gear that feels right, especially on flatter
roads.
> Is it a change worth considering?
I wouldn't consider it while there are 13-26 cassettes* and smaller
chainring(s)**. A road Shimano type triple chainset takes an inner ring
down to 24 teeth, middle 38t. Note that minimising the size of the outer
ring as well will help you get the lower gears working better by allowing
the chain to be shorter than it would have to be otherwise, and the front
mech to be lower.
I know changing the both cassette and chanrings could work out expensive,
but customising the gears is one of the very best ways of improving a
bike, IME. It may be cheaper to replace the whole chainset if you find
another with more suitable rings, but check whether it requires the same
bottom bracket or not.
*
www.settlecycles.co.uk/shop
*
www.chainreactioncycles.com/Models.aspx?ModelID=1864
* Also possible to build a custom cassette (eg 13-28) by canibalising
various cassettes or using Marchiso sprockets.
** Stronglight and TA (TA best) from
www.settlecycles.co.uk/shop
- Inner: 74mm or "ATB5"
- Middle and outer: 130mm or "Shimano Race". Middle doesn't /have/ to be
middle specific, a double inner will work.
~PB, suggesting 26/38/50 + 13-26