Bicycle Mechanics - Chainring and crankset questions

Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.
deepakvrao
07-10-12, 10:32 PM
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/Models.aspx?ModelID=34733
http://www.chainreactioncycles.com/Models.aspx?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.
fietsbob
07-10-12, 11:44 PM
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.
HillRider
07-11-12, 05:55 AM
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.
deepakvrao
07-11-12, 05:50 PM
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.
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].
Powered by vBulletin® Version 4.1.12 Copyright © 2013 vBulletin Solutions, Inc. All rights reserved.