fita1440

I have an older S-Works Tarmac SL2 and want to change to a compact crankset. Can i change the rings only? Do I need to get a full crankset? How about the bottom bracket? I am new here so any help would be appreciated. I just have no interest in trying to push a 53-11 or anything close. I just never get down there.

Bill Kapaun

You'd have to deal with FDER adjustments which can be a pain.
Is there a different cassette that would give the gearing you need?
Much simpler.

fita1440

I've looked at that but I spend all my time in the bigger toothed cogs on the back and really have no interest in ever trying to push that big. I believe that a compact or even subcompact like my gravel bike would suit me much better. My gravel bike is 48/34 and I have a 11/25 cassette, love that combination so far.

cxwrench

I don't remember exactly which crank that bike had, is it a carbon Specialized? To go from standard to compact you'll most likely need to get the 110mm bcd spider and then the rings you want to use.

deacon mark

If it is a press fit Bottom bracket which I think it is and a clamp derailleur, then I would upgrade to Shimano compact with Praxis BB to get the crank in good shape. I personally think you might be better if you really like the bike and ride to simply upgrade to current shimano 11 spd groupset. If you can do the work yourself this is the way to go so everything is nice an tidy. Probably need new rear wheel if not 11 spd hub.

sch

It is unlikely a 34t CW will fit on the spider of the 53/39, the mounting bolt circles are off. Finding a 50t CW to fit
the 53t slot would be possible but expensive as these tend to be specialty items from obscure makers who are
proud of them. Your BB is almost certainly 24mm spindle diameter so your best bet is rummaging for a 50/34
crankset and installing it in the existing BB. Shimano are available for ~$150 or so if sub Ultegra. Then dropping
the FD down a bit (~1/2") to fit.

Going to 11 spd will run upwards of $400 to 600.

delbiker1 

You could change out the chain rings to 50 or 48-38, change the cassette to one with bigger cogs depending on what gearing you are looking for. With 50/48- 38 up front and like a 13-28/30 in the back, that might work for you. Just have to adjust the chain length and derailleurs.

The Shimano 105, 7000 groupset is really sweet. Price has gone up since I purchased one earlier this year. Looking at $500 to $600 shipped now, I believe.I found it pretty easy to install and set up, and I am by no means an accomplished bike mechanic. Took me a while and a bit of thinking on it before I pulled the trigger, very glad I did. However, that is on an English threaded BB bracket. I had to get a wheelset anyway as it was used on a new Soma Smoothie frame/fork.

alcjphil

How much older is it?
What make and model crankset does it have?
What is the BCD of that crankset?
If it is a 130 mm BCD, the smallest small ring you can use is 38 teeth
If your current crank has a 130 mm BCD you need a new crank if you want compact rings
The bottom bracket? Depends on the exact age of the bike and the current cranks. If you buy a new crank of a different brand you will probably need a new bottom bracket

cxwrench

It's not unlikely,it's impossible. Also, it's highly unlikely that it's a 24mm, it's most likely OSBB w/ a 30mm axle.

If it's the S-Works crank he can change the spider and go compact...if he can find one, which should be possible.