I want to replace my current TruVativ 52/42/30 crankset and keep seeing triples advertised as "ten speed". Will these ten speed cranksets work with my 12/25 eight speed cassette? If not, what is it about these ten speed cranksets that makes them only work with ten speed cassettes?
I would also like to replace the 12/25 cassette with an 11/30 eight speed cassette. Are there any foreseeable concerns with this other than the cross-chain issues I already have, but don't mind?
'''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
9 and 10-speed cranks have the chainrings slightly closer together to keep the narrower chains from dropping between the rings on shifts. They may cause some chain rub if you use the wider 8-speed chain with them You could use a 10-speed chain with your 8-speed cassette with no problems.
The 11/30 may exceed the wrap capacity of your rear derailleur.
Spec' Tarmac (road), Ridley Fenix (commuter & fast tourer), Salsa Mamasita (MTB), CoMo Speedster (tandem), Surly Big Dummy (cargo), Airnimal (folder)
If you do decide to go with an 11-30 cassette then you may be able to get away with not replacing your rear derailleur. Officially, the largest rear cog the derailleur will cope with is 27 or 28 teeth, but on many frames it is possible to use a 30 tooth (it depends partly on the exact shape and angle of your derailleur hanger). Screw the b-screw in all the way, or use a longer screw, and the upper pulley may be able to clear the largest cog when the chain is on the small ring in front and large cog at back. Chain wrap is certainly going to be a problem, but only in the small-small gear combinations. If you avoid using the smallest 3 cogs on the back when in the smaller chainring, then the derailleur should be able to wrap enough chain and it will never be slack or rub on itself in the lower part of the run.
A 9- or 10-speed chain will help you to cross-chain more with the 10-speed crankset without having the chain rub on the outer rings, but you could also stick with an 8-speed chain and put up with the rubbing or avoid cross chaining (you already need to avoid it when in the smaller chainring due to the chain wrap capacity issue). However, when switching from a 12-25 to an 11-30 cassette, you'll probably need to lengthen the chain anyway, so if the current chain has some wear already then it is probably worth going with a new one, and so a 9- or 10-speed chain would make the most sense.
I have the exact same setup: 8-speed, triple 52-42-30, 11-30 in the back. I saved myself a ton of money and effort simply by removing the granny ring from the cranks and locking out that position on the FD. The 11-30 in the back allows my 42 in front not to be too tall on even the biggest hills.
All of this is moot of course if your cranks actually need replacing >:-)
So my best bet (to use a 10 speed triple crank) is to: switch to a narrower 10 speed chain and stick with the 12/25 cassette? I can live with that. Thanks.
The 8 speed chain will be less expensive than the 10 speed-don't throw good money away.
The narrower 10 speed chain won't work as well on the wider teeth sprockets of the 8 speed cassette.
Lengthening the chain will safely accomodate the 30 T rear cog.