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Old 07-10-12, 10:32 PM   #1
deepakvrao
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Chainring and crankset questions

Hi Guys,

Wife and I have Bike Fridays with a

Cranks - Alloy triple 170mm 30/42/52 130/74 bcd 119mm

Big chainring sometimes gets damaged in transit, so was thinking of carrying a spare.

Couple of questions:

1. Will I need to raise the FD if I put in a 53 instead of a 52?

2. When I see online, I see 52T chainrings in the same BCD [130] as 'double' and 'triples'. What's the difference?

http://www.chainreactioncycles.com/M...?ModelID=34733

http://www.chainreactioncycles.com/M...?ModelID=34734

3. Currently bikes are 8 speed, so can I put in a 9 speed or 10 speed chainring?

Really appreciate any help here.
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Old 07-10-12, 11:44 PM   #2
fietsbob 
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1t adds to the circumference & so to the diameter, so perhaps, yes..
what is the difference? 1/2 inch.. the pitch between chain pin centers.
the chainring tooth has to be cut thinner for a 10 speed chain,
so ever-so slightly less surface to share the wear load of the chain..

you can add one of bike Friday's big chainguard discs to a triple
adding a spacer outside the outer chainring..

I have a chainguard outside the outer chain ring on a touring bike,
and a chain minder to catch over-shifts on the inside..
So ... no missed FD shifts.

Last edited by fietsbob; 07-10-12 at 11:54 PM.
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Old 07-11-12, 05:55 AM   #3
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1. Yes , you will have to raise the fd if it is currently close enough to the 52T ring. A 52T ring has a diameter of 8.28" and a 53T is 8.44" so the radial difference is .08" or about 5/64".
2. A "triple" middle chainring has ramps and pins on it's inside face to assist the shift from the granny ring to the middle. A double inner ring does not need these shifting assists on it's inner face.
3. If you use 9 or 10-speed chainrings with an 8-speed chain, the probability is the chain will rub on the outside ring when in the middle ring.
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Old 07-11-12, 05:50 PM   #4
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Quote:
Originally Posted by fietsbob View Post
1/2 inch.. the pitch between chain pin centers.
the chainring tooth has to be cut thinner for a 10 speed chain,
so ever-so slightly less surface to share the wear load of the chain..
So, will it really make a practical difference? I am able to find mostly 10 speed chain rings online.

Quote:
Originally Posted by HillRider View Post
1. Yes , you will have to raise the fd if it is currently close enough to the 52T ring. A 52T ring has a diameter of 8.28" and a 53T is 8.44" so the radial difference is .08" or about 5/64".
2. A "triple" middle chainring has ramps and pins on it's inside face to assist the shift from the granny ring to the middle. A double inner ring does not need these shifting assists on it's inner face.
3. If you use 9 or 10-speed chainrings with an 8-speed chain, the probability is the chain will rub on the outside ring when in the middle ring.
Ponts 2 & 3 - any effect if it is the biggest chainring that I change? I see even the 52t chainrings labelled as double/triple [links given in original post].
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