I have a 2010 P2 with 50/34 chainrings. I often find myself running out of gears and would like to move up to a 53 big ring. Can I just replace the big ring, or would I need to replace both?
Jason
I’m just a shade tree bike mechanic, but I’d say the chain drop from a 53 to a 34 ring might be a bit much and the chain length discrepancy might be more than your rear derailleur arm can take up. Most drivetrains that use a 53 big ring use a 38 small ring. If you make the change, you’ll probably need a new and slightly longer chain.
They do not need to be replaced at the same time. The wear on each will depend on what gears you use more.
Your FD may/will have a lot of trouble shifting across that tooth differential. Most are rated for 14-16T max, so 50/34 is about the limit. 52/36 is an option.
What is your cassette? Do you have an 11 ring on there.
Alternatively, and almost the same price, replace the crank. I have a 55/42 as well as a 53/39 and I will swap as needed. Then again, this is fairly easy with the Shimano Dura-Ace Hollotechs, but your experience may be different. I picked up basically a brand new 53/39 full crank set for around $160.
You will need to keep the chain rings within a certain range. You may be able to shift with a 53/30, but my guess is that your chain will be dragging on the bottom of the derailuer in the 30, or you will be banging into the teeth and unable to shift into the big.
Likewise besides the physical limitations on shifting up front, the difference in chain length from big-big to small-small with a 53/30 will mean you will have to scrap several gear combination, which starts defeating the purpose. Your rear derailuer will either be going vertical in the bigs, or so loose the chain is slapping around in the smalls.
This is Slowtwitch. Nobody uses the small ring.
On a typical compact crankset, the bolt pattern is a 110 bcd (bolt circle diameter). Typical compact cranks run a 50/34.
To switch to a standard crankset that runs a 53/39, you’ll likely need a new crankset with a 130 bcd. If you can find a 53 ring in a 110 bcd, you do not need to change both, but I am not aware of anyone that makes that size ring with the 110 bcd.
I’m betting you’ll need a new crankset. Be aware of the bottom bracket type and compatibility when making that switch.
I’m betting you’ll need a new crankset. Be aware of the bottom bracket type and compatibility when making that switch.
Probably not. Assuming that the OP has an FSA crank/BB, 110mm BCD 52/36 chainrings are available.
As JoeO mentioned, do you have an 11 tooth cog on your cassette? If you have a 12 tooth cog as your lowest gear on your cassette, then the cheapest and easiest solution is to replace your cassette. Don’t underestimate the difference between an 11 tooth and a 12 tooth cog; it’s quite a bit. FWIW a 50/11 is a bigger gear than a 53/12.
Thanks for the replies and suggestions. To answer your questions, I do have a compact crankset, and I have a 12-25 cassette. The thought of replacing the cassette is interesting and brings up a few more questions:
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If I got a cassette with an 11 tooth small cog, what would the big cog be? And what would be the impact to my overall lowest gear be as compared to replacing the chainring? In other words, if I kept my stock 50/34 chainring setup and replaced the cassette with a 11-?, how would the lowest possible gear compare to keeping my stock 12-25 cassette and going to a 52/36 or 53/38 chainring? Basically I’m looking to add bigger gears while sacrificing as little of my low gears as possible. (duh)
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If I moved to an 11-? cassette, could I keep the same chain length as my current setup with the 12-25 cassette? I do intend to buy another set of wheels this winter, so if I can run 2 different sized cassettes on the same chain, than this becomes a no-brainer, I’ll just run different cassettes on different wheels.
Don’t underestimate the difference between an 11 tooth and a 12 tooth cog; it’s quite a bit. FWIW a 50/11 is a bigger gear than a 53/12.
Hmm, yeah I guess it would be. I come from a motocross racing background and the rule of thumb in MX is that one tooth up front equals 3 in the back. I just need to keep reminding myself that gearing on bicycles is exactly the opposite as motocross bikes.
ST’ers never need to replace the small chainring as we never use it. I removed mine entirely and saved ~110grams.
ST’ers never need to replace the small chainring as we never use it. I removed mine entirely and saved ~110grams.
Wouldn’t the “true” ST solution be to remove the cassette, small chainring, and derailleurs and run a fixed 53/11 gear? That should save a ton of weight.
Jason
Wouldn’t the “true” ST solution be to remove the cassette, small chainring, and derailleurs and run a fixed 53/11 gear? That should save a ton of weight.
Jason
Nah, sometimes that 55x 19/21/23 is nice to spin out the legs so that you can save something for the run…
You can go to sheldonbrown.com/gears and play with gear ratios until your heart’s content (I highly suggest it).
The most common 11 tooth cassette has a large cog with 23 teeth, though others do exist. If yours is a 12-25 and you’re going to get another set of wheels over the winter I’d definitely go with an 11-23. Then you’ll have the two most common cassettes around. You can interchange these cassettes without having to change anything else on your bike (like the chain).
Your 12-25 is: 12-13-14-15-16-17-19-21-23-25
An 11-23 is: 11-12-13-14-15-16-17-19-21-23
As you can see, you’re basically giving up your easiest gear to get one bigger gear. All the others will still be the same. If you have any other questions, let me know.
Cheers.
If yours is a 12-25 and you’re going to get another set of wheels over the winter I’d definitely go with an 11-23. Then you’ll have the two most common cassettes around. You can interchange these cassettes without having to change anything else on your bike (like the chain).
Boom, now we’re cooking with gas. Done deal. Thanks!
Jason