Campagnolo Compact
 

Rather than buying a new compact crankset can the chainrings on a Record 11 speed be replaced from 53/39 to 50/34? I see a 34t with 135BCD but don't see a 50t with 135BCD. Confirm that a 53/34 won't work. Thanks.

A 34T chainring will not fit a 135 mm BCD, 39T is the smallest. If you saw one advertised, it was a mistake. All compact cranks use a 110 mm BCD which will accept down to 33T.

Excel sports has one listed.

Good, buy it and see if it fits. However, I'd call them first to check. I'm certain it's a typo

+ Campag figured out offsetting 1 bolt of 5, makes their replacement chainrings exclusive to themselves..

As others have noted, you cannot use Campagnolo compact rings on a record crank because the bolt circle is different (110 vs. 135). But that doesn't stop you from using any 135bcd 50t ring on your Record crankset. There are a few producers of rings to fit the 135 pattern,and there' no reason not to make the change to get gearing more suited to your needs. You are limited to 39t minimum because any smaller would have teeth within the bolt circle, but that's the only restriction.

Long before anyone came up with marketing "compact drive" riders were setting bikes up with the rings of their choice. My wife's bike is set up 39/46 which with a 12/26 cassette gives her gears that she can actually use, vs. what a 53t would yield.

The 53T large chainring on my Record crankset is not the problem for me. It's the 39T that's at issue since I find I can't make the hills with it. I don't want to spend that kind of money for a new crank so I think that changing the cassette to a Chorus 12-29 may be the best and cheapest option. I think that I can get one for about $150. Are there any problems with that or are there other options?

There may be issues with chain length, but you'd probably want to replace that at the same time. The other issue is RD take up capacity. The new combination will exceed the standard short cage RDs capacity. You have 2 options, use a 50t outer to bring it back into range (sum of the differences in teeth R+F), or decide in advance that you won't use the 39t with the smallest few sprockets.

In any case make sure to measure that the chain is long enough to loop the 53/29 combination without taking the RD cage to the end of it's travel (or measure skipping the RD big+big +1"). Later you'll find out which of the small/mall combinations are off limits.

Regardless if your preferences, plans or expectations you need to allow the big/big combination to work because the consequences of shifting into a combination that the chain is too short to loop is damage to the hub, derailleur, sprockets, and sometimes the frame. The consequences of shifting to one for which the chain is too long is a droopy chain.


BTW- I don't know what you have now, but if it's a 26t, going to a 29t will only get you about a 11% reducttion in your low. It would be slightly less than going from a 23 to 26. If you only need incremental improvement (ie one gear lower, the 29t may make sense for you.

OTOH if you need more, consider going triple. You don't need to replace the crankset, there are "tripleizer" inner chainrings that will allow you to attach a 74bcd granny to the middle ring. This will allow you to choose something that will truly give you low climbing gears. You will have to buy a new triple FD, but hsat should cost less than the cassette would. And of course, you still have the issue of limited capacity for the RD, but you'd only be using the granny with the larger cassette sprockets, so this shouldn't be an issue.

Note: the photo I linked isn't specific to your needs. Be sure you buy a 135bcd 39t triplizer.

[Almost same thought .. with FB]
Just may have clearance troubles with the short cage RD..getting over the 29t cog,

& wrapping up the longer chain required.

(53+29) - (12+ 39)

A record 11 RD has enough wrap for the 53/39 and 12-29, but if it's a 2009 model, the upper jockey pulley probably won't clear the 29T cog. Newer RDs will work with a 12-29, since the made a modification to the "B" screw mechanism.

Quote - "BTW- I don't know what you have now, but if it's a 26t, going to a 29t will only get you about a 11% reducttion in your low. It would be slightly less than going from a 23 to 26. If you only need incremental improvement (ie one gear lower, the 29t may make sense for you."

No, I'd be going from an 11-23 to a 12-29 cassette. I think that's a pretty big gain.

Then the 12-29 should be a big help and may solve the problem entirely. just be careful about chain length. You will almost certainly need a longer one.

BTW- if you live in a hilly area, how did you end up with a 11-23 in the first place?

Because I am/was a newbie and didn't know what I was doing. I wanted to build up a good solid carbon bike that would last and something to be proud of. It was a costly mistake but the only one ..... so far. I'll sell the Record cassette since it only has a couple of hundred miles on it. I haven't ridden the bike much since I'm working away from home and instead have put hundreds of miles on a cheap SS I put together.