Bicycle Mechanics - compact crank question

I have ultegra front derailler do i need to switch it when i go from and 53x39 to a compact crank?

I have changed two bikes to compact 9sp. (one 48X34 another 50X36). Both have Ultegra 9sp front derailleurs. Both shift fine with the original derailleur....I did have to lower the der. a bit. I cannot say about 10sp but I see no reason why there would be a difference. I use SIS on both.

Short answer: No, just move it down.

Move it down no problem. Have read that braze on mounts sometimes have issues getting the der. low enough.

If you're extremely particular and sensitive about shifting performance then you might be able to detect a little roughness due to differences in designed curvature but if you're like the rest of us and don't generally feel the urine under the matress then it will work fine by just lowering it as others have said.

Shimano's says their compact crank works fine with their regular double front derailleurs and do not offer a specific compact fd. FSA and Campy make specific compact fd's for use with their compact cranks.

I just built a bike with a Shimano R700 compact crank and Ultegra 6600 front derailleur and it works perfectly. As others have noted, if you are converting an existing double to compact double, you'll need to lower the front drailleur a bit to compensate for the smaller diameter chainrings. Look at the front derailleur setup instructions in the Repair How-to section at parktool.com and use the penny like they show to set the proper chainring/derailleur distance.

I have an older Raleigh Technium Pre that had a Suntour fd and a 40/52 Sakae crankset. I put an FSA Gossamer Compact 34/50 and only had to lower the fd a little and it shifts fine. Just my experience, hope it helps.

If you're extremely particular and sensitive about shifting performance then you might be able to detect a little roughness due to differences in designed curvature but if you're like the rest of us and don't generally feel the urine under the matress then it will work fine by just lowering it as others have said.

Ha ha ha!


back to business..

I'm running a 105 front der, works great, FSA compact 50X34. I had a 105 tripple that did not work out as well... thought the larger cage may work better, but it didn't.

Thanks for the input guys.