Bicycle Mechanics - compact to standard chainrings

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captnfantastic
05-12-09, 10:49 AM
I have a 50/34. I want to get a 52/39. Can I use my existing crank and/or front derailleur? I know I will need a longer chain, I was curious as to any other changes I would need to make.


JiveTurkey
05-12-09, 11:23 AM
You can find 52T and 39T chainrings in 110mm BCD (compact crank vs the 130mm BCD of standard road cranks). E.g.: http://www.sheldonbrown.com/harris/chainrings/110.html

Make sure you get chainrings designed to work as a set (rather than a a single chainring). This is more important for the outer chainring as it should have little pins to help take the chain up from the inner chainring. But, you may as well get a matching set that was designed to work together.

There aren't many compact-specific front derailleurs out there, so your current FD should work great.

Yes, you'll need a new chain and depending on how much use the cassette has gotten, you may want to replace it along with the new chainrings and chain.