rebuild question

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Joined: Tue Dec 04, 2012 08:44 am

rebuild question

Postby ithomasw » Tue Dec 04, 2012 09:03 am

Hello All,

I have on my bike a SRAM Apex groupset with a compact chain set of 50 -39. matched to a 11 -32 sproket.
most of the time this is totally fine, however on weeks ride recently over some very big hills, bigger than I have ever encountered before I had to walk a lot more than I expected! ( In my defence I was carrying a bit of weight on the bike ! ) I soon realised that I needed lower gears for the touring I have started doing, so rather than go for the expensive option of a new triple chain set and levers I was planning to reduce the size of the front chain rings to 42 -27, such as an FSA comet chain set. ( I read an article in CTC mag recently on a expedition type bike that had this FSA comet chain set 42 -27.

My questions are - do I need to buy this or can I just buy smaller chain rings and fit them to the crank ?
Also would the standard SRAM apex front mech cope with this reducing or should that be changed also to such as SRAM X7 ?

thanks in advance.

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Re: rebuild question

Postby k-dog » Tue Dec 04, 2012 09:15 am

50/39 would be an odd combo - usually either something like 52/39 or 50/34.

If 39 is the smallest then you won't be able to change the chainrings for smaller ones as the bcd of the cranks is too big - if it's the latter then you might - but you'd probably have to change both as too big a gap doesn't work (hence 42/27 like you've seen).

But, 34/32 is a tiny gear - if you can't climb with that then maybe some more practice is required. Not sure changing to outrageous gearing will help much - you'll just move really really slowly.
I'm left handed, if that matters.

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