Crankset upgrade - advice needed

MrSkinny

I would like to replace the single 48t crankset on my steel bike with a compact to make the Wicklow hills a bit more accessible.

Currently the bike has a 9 spd Shimano cassette (12-23t) and DT shifters. Am I restricted to a 9 spd crankset or can I also consider 8/10 spd cranksets? Will the existing chain (which I assume is 9 spd) work with the other cranksets?

And would it be best to stick to Shimano or is it OK to mix and match different makes?

Apologies if these are dumb questions. Been reading up on this but I'm still not entirely clear what components will/won't work together.

macnab

The bike has a 9 spd Shimano cassette (12-23t)

Consider fitting a 12-28t cassette.

Am I restricted to a 9 spd crankset?

10 SPD will work, 8 SPD will probably require an 8 SPD chain which is wider.

Will the existing chain (which I assume is 9 spd) work with the other cranksets?

Chains get thinner as you go up in speeds. I have briefly used a 10 speed chain on an 8 speed drive train, the chain was too narrow to allow it seat onto the gear teeth correctly.
Conversely an 8 speed chain on a 10 speed drive train will be too wide, this will mess up your gear shifting smoothness.

Stick to Shimano?

I generally mix Shimano and Sram drive train parts without problems. Keep in mind that control items differ slightly though, the pull ratio on Shimano brake levers is not the same as Sram levers. So use Shimano levers with Shimano brake callipers and Derailleurs.

Seaswimmer

What not buy a new cassette as advised above but also look into a smaller front ring. Maybe 42t or even 39t which coupled with a 28 will give you a lower gear than you have now. You may spin out on long descents but I tend to mostly freewheel these now days anyway..42/39t to 12 gives you a reasonably high gear anyway.

keeps everything simple and low cost.

It would not be low enough for me but may be ok for you..

TonyStark

I find this : http://sheldonbrown.com/gear-calc.html to be an utterly fantastic resource when it comes to gear calculations and seeing the effect of different combos.

MrSkinny

Many thanks for the replies. Some very useful info and a couple of ideas to think about.

I had also considered adding a smaller ring to the existing crankset but it's 122mm BCD and it seems a bit difficult to source parts for it.

Maybe a new cassette will be the easiest (and cheapest!) route. I can see Shimano make 11-30t and 11-32t cassettes and that should give me low-enough gears.

Food for thought ...

Cee-Jay-Cee

If you fit a 30T or 32T cassette then you will most likely have to change the chain (or add in a few kinks if you have some) and you'll need to ensure your RD will accommodate a larger cassette.

MrSkinny

Cee-Jay-Cee wrote: »

If you fit a 30T or 32T cassette then you will most likely have to change the chain (or add in a few kinks if you have some) and you'll need to ensure your RD will accommodate a larger cassette.

Ah ... it's never straightforward, is it?