What is the impact of changing to a smaller chainring? My road bike has a Campagnolo Veloce gearset. It's running 53 and 39 tooth chainrings. I have a 13-25 10sp cassette.

I find that a lot of the time when I'm cruising, I'm on the big chainring and in the 3rd or 4th largest gears on the back. There is a fairly significant chain angle. Because of this, the chain is a bit noisy and I'm sure it's stressing the drivetrain a little. Also, when I need to drop down a gear I quickly need to drop onto the small chainring which necessitates significant adjustments on the rear.

I'm thinking of changing the 53 chainring to a 50t. I am happy to lose a little top end speed.

According to my theory, dropping a 53t to a 50t will reduce my gear ratio by 1.06 (53/50). Which would be the equivalent of switching from a 17t on the back to an 18t. Assuming this is correct, it's not going to have a very big impact, but it might be enough to make it worthwhile.

I know there is an option of using a 3 chainring crankset, but I think that will be a bit too expensive and still won't solve the core issue of getting the right sized large chainring.

The other option is to change the cassette but I can't see many that would really make much of a difference. If I could get a 15-25 that'd probably be about right.

My questions are:


Will the change mean I need to change or adjust the front derailler, the rear derailler or  the chain?
Will there be any other impacts I haven't thought of?
Any other ideas to solve the problem?


EDIT: I can't seem to find a 135mm BCD 50t chainring. I asked my LBS and they said no go. ChainreactionCycles don't have the combination I want. Can I get a 50t 135mm BCD campag chainring? If not, what can I use as an alternative?

EDIT: I've found that BBB make a campag compatible chainring that looks like a good option

EDIT: As indicated here the BBB chainring doesn't fit. Looks like a proper compact crankset is my only option now.
I would consider changing your crankset to a true compact, 50t/34t, and running an 11/25 rear cassette. 

Campy actually made a specific derailleur for running a compact front, because they said that the 50t doesn't work well with the standard front derailleur (that may be a function of the tooth differential, so it may not apply if you leave the 39t in place). 

(Edit: It does appear that my data on the campy front derailleur may be outdated. Their 10 speed Chorus and Record had an individualized front derailleur, but current product appears more universal.)

The 50t x 11t combo is a 119.6in gear, compared to 107.2inches for the 53t x 13t you're running now. 

It will give you a slightly faster gear than current, a better climbing range, and slightly crisper shifting. Downside is you have to buy the crank set and cassette, not just a chain ring.

Check out UBI gearcalculator for more info on how gearing changes will affect you.

Hope that helps.