Is it possible to switch a compact crankset to standard by swapping out the chainrings? I have an Ultegra fc-6750 crankset that I’d like to convert to standard. Can I just buy standard size chainrings - or is the spider itself different between standard and compact?
Thanks!
The bolt centers are different. A compact is 110mm Bolt center diameter, and standard crankset is 130mm BCD.
You can get 52/38 chainrings and be right about there. I have 52/36 on my tri bike and love it.
Not with that generation of cranks no.
The current 11spd ones yes.
Also you may need to extend the chain depending on the cassette you were running previously and are intending to going forward.
…and adjust the front derauiler height.
52/36 is probably the best all around combination for 99% of riders out there on 99% of courses. You rarely need to apply power above 38-40mph, and most riders rarely see hills where you can’t hold 6-8mph at FTP with a 11-28.
However, some riders do need lower gears on some courses in a full distance IM if they are 6+ hour riders. Max watts for them might be 85-90%, some as low as 2 w/kg. At that point, your looking at 5-6mph on some hills.
I rode a 52 on both a hilly and flat course and it was great. Almost pefect on a flat course. But I could have used a 50 on either as well. The 11T makes all the difference.
For most cranksets including ultegra cranksets it won’t work due to the spider size (usually 110 for compact and 130 for standards). If you have a dura ace crankset, then it can work for all chainrings.
For most cranksets including ultegra cranksets it won’t work due to the spider size (usually 110 for compact and 130 for standards). If you have a dura ace crankset, then it can work for all chainrings.
Just to elaborate on that…
Current gen Dura-Ace (9000) and Ultegra (6800) use the new 4-bolt 110 bcd pattern that can use a 53, 52, or 50 big ring and a 34, 36, or 39 little ring.
Forgot about the newer ultegra. So all the ones with a 4 arm spider correct?
Yes.
older 5 bolt still has 52/36 available. 52 vs 53 is splitting hairs and has the advantage of better chain line in a lot of typcial cruising speed depending on your cassette.
For the cost of new Ultegra rings, you can buy a complete 105 crank. Its’ a good opportunity to try a different crank arm length if that will help you position on the bike.
older 5 bolt still has 52/36 available. 52 vs 53 is splitting hairs and has the advantage of better chain line in a lot of typcial cruising speed depending on your cassette.
For the cost of new Ultegra rings, you can buy a complete 105 crank. Its’ a good opportunity to try a different crank arm length if that will help you position on the bike.
How is keeping the 34 inner combined with the 52 outer? Does it allow for decent shifting? Not that I need a 34 inner, but I also don’t need to spend money on a 36 tooth inner either.
And fit a new cable if the existing is trimmed short… 
Is it possible to switch a compact crankset to standard by swapping out the chainrings? I have an Ultegra fc-6750 crankset that I’d like to convert to standard. Can I just buy standard size chainrings - or is the spider itself different between standard and compact?
Thanks!
You can find standard sized rings with the compact (110 BCD) bolt circle. You can for sure get 39x53 rings. I’m not so sure whether or not you can get larger big rings than 53.
But if you just waltz into a shop and ask for a 39 and a 53 tooth chain ring set you will get the wrong ones (130 BCD) unless you specify that you’ve got a compact (110 BCD) crank set. They will almost surely have to order them. Or you can just go to Google and find them online yourself and order them direct.