New chainring for Sora 9speed
#1
New chainring for Sora 9speed
Hi! I have a Surly LHT with a Shimano Sora triple chainring, 50-39-30. Can I, and would it be advisable, to put a smaller chainring on the small end, say a 24? I'm old, fat, bad knees, bad disposition, and a beer gut, if any of that matters!
#2
Really Old Senior Member
What's the BCD of the smallest ring?
It may be large enough that you can't go as small as you want, if at all.
It may be large enough that you can't go as small as you want, if at all.
#3
Senior Member
Join Date: Sep 2010
Location: Roswell, GA
Posts: 8,321
Bikes: '93 Trek 750, '92 Schwinn Crisscross, '93 Mongoose Alta
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https://wickwerks.com/bolt-circle-diameter-bcd/ cheat sheet near bottom
#4
It seems that the chainring setup I have has asymmetric bot spacing. 4 bolts, 64-ish between 2, and 45-ish between two. That, I am sure, complicates things a bit. Is my answer a new crankset, if I want the small gear bad enough?
#5
Expired Member
Yes. Shimano specs are 110/74 but judging from the pic that doesn't mean what it once did. Shimano has made various "Trekking" cranks through the years with useful chainring sizes. AFAIK the 9 and 10 speed versions weren't sold in the US but were sometimes available on ebay. I think the 9 speed was T661.