Road Cycling - Rear wheel component spacing questions...

What's the biggest cassette/freewheel that will fit between a 126cm rear?

Currently, I have a 6-spd on Trek Matrix wheels, but I might just upgrade to a 105 gruppo and was wondering if a 105 8 speed will squeeze in.

PJ

It is unlikely the cassette will fit your hub. Eight speed is spaced 130, but if you hae a steel frame you can spread it to fit.

Ok then,

Will I be able to keep my 6spd rear and just mount a 105 crankset?
Or will this create problems with chain width, etc.?

I'm assuming that a 105 crankset is designed for 8-9spd rears...by the way I still have downtube friction shifting up front but the rear is controlled with downtube index shifting.

PJ

You will be able to use the six speed with a newer crankset, just keep the wider chain.

DEMON

Thanks...

PJ

PJ-

I have the exact combo you're mentioning: new 9-sp. 105 crankset with 7-spd. freewheel (both 6 & 7-spd. use 126mm rear spacing, just different cog-to-cog spacing for indexing). With a 6-7-8spd. chain it works just fine as demoncyclist mentioned, with just one exception. You need to be careful when shifting from the larger chainring to the smaller. If you just jam it down, you'll throw the chain past your smaller chainring, even if you're in your middle rear cogs, and have your limit screws correctly set. Reason being, the spacing between large and small chainring are set for the narrower 9-spd. chain. My LBS recommended changing the smaller chainring to a 6-7-8spd. chainring, but I've found that if I take it slow on that shift, I have no problem. Smaller chainring to larger is also no problem.
Good luck! :)