Bicycle Mechanics - Is this gear combination allowed?
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06-14-03, 07:48 PM
My touring bike currently has
26-36-46 RSX crank
12-32 shimano "P' 8 sp. cass
Deore LX rear derail
RSX front derail
RSX STI Shifters
Can I put a 22 ring on the smaller one
(I need to put little lower gear for loaded touring
but short of changing the whole crank to
something like Deore 22-32-46, may be I can just change
only the small chain ring??
I know there's ring-difference that is not allowed,
just not sure how it will be for me.
06-14-03, 08:22 PM
You can go down to a 24 on your RSX crankset. That shouldn't pose too much of a challenge to an LX rear derailleur unless you shift to the small-to-small combo.
If it were me, I would consider getting some beefy top-quality 7075-alloy chainrings instead of the stamped-steel RSX rings, while you're at it. Real Design makes some awesome ones, as well as RaceFace. Avoid the 6061 models and go for the hard, gouge-resistant, long-wearing 7075 versions. I see some on sale here (http://cambriabike.com/SALE/chains_rings/index.htm) for $70 for the RaceFace 24-34-46 set in the 74/110mm pattern that you need (get the black ones, not the unramped silver ones).
One thing about the RSX shifters, too... the front shifter doesn't have the trimmability of most STI shifters, or not the ones I've used anyway. They rely on the chainrings' shift ramps to help them get the granny-to-middle upshift, in particular, so you need rings with shift ramps/pins. If you go on long tours then it might be worth thinking about some bar-end shifters, which have a fail-safe friction mode to fall back on (and friction front shifting all the time).
There are 8-speed cassettes that have an 11-34T setup, too. The last jump is pretty dramatic (from a 26 to a 34), so it's not that great of a solution, but it was worth a mention I guess.
Anyway, that's my 2c, hope it is food for thought :)
it doesnt sound like a 22 ring is in the cards without changing the other two rings if the following chart is right:
on the otehr hand htis guy had a 24 tooth differerence:
06-14-03, 08:44 PM
The RSX is using a 74mm inner bolt circle, so I think 24T is the physical limit. Maybe that LX crankset would be a good idea, if the lower high gear isn't an issue.
06-14-03, 09:47 PM
I installed a 24 ring on my wife's old LX equipped Cannondale. Shifts well.......but at less than 20 gear-inches, it's faster to walk slow than pedal!
06-15-03, 05:42 AM
If your der handles the 32T in back you might try slipping on a 34 instead. This with the 24 would give you that little extra low gear. Rear ders will often handle a few more teeth than rated for. You just don't know until you try.
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