Chainring upgrade

One of my bikes has a Dura Ace R9100 50-34 compact chainset. My other bikes both have 52-36 chainsets. I prefer the 52-36 set -up and am looking to upgrade the Dura Ace to 52-36. A brand new R9100 52-36 crankset costs about £400-£500. However, if I buy the chainrings separately (a 52 tooth and a 36 tooth), it comes to about £200. I know I’ll need a new chain to accommodate the bigger rings. I’m pretty sure it will be a straight forward job of fitting the new chainrings to my existing cranks (after adjusting the height of the front mech). As far as I can see the BCD on R9100s - regardless of chainring size - is 110mm.

Can anyone confirm if it’s that simple? Surely I don’t need to replace the whole crankset…

I have a pro mechanic buddy he changed my 52/36 rings to 53/39 like in 2 minutes. Is true he also had to change the chain for me but it was easy peasy watching from the outside.
I would be massively surprised if its anything more difficult from compact to semi compact.
By the way I have Ultrgra Di2.


Yes, all the same. You will need a T30 Torx for the chainring screws and recommend a torque wrench, especially for the NDS crank screws.

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Cheapskates self-wrenchers like me keep the bit of chain they remove when initially fitting the chain - just for that one time in a lifetime where it will be needed.

You just convinced me to keep doing that hoarding of 5-6 links. Just in case.

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Perfect. Thanks very much.

Biggest pain of that job can be adjusting the front derailleur…


I changed from a 50/34 to a 52/36 (both sram) and kept the same chain. There’s an equation on the parktool website to work it out. You need to know you chainstay length among other things. I calculated I needed a half-link more, so I just didn’t bother and haven’t had any issues with it.

Apart from that, yeah it’s that simple.

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Yep, not my favourite job.

downfall of many a home mechanic.

Limit screws should stay in same place (unless you’re mounting really weird chainrings). You need to bring the FD up so it clears the (larger) outer chainring. The rest should be pretty close… the lateral movement is the same.


For two teeth you can probably use the same chain unless the current chain was on the shorter side. With new chainrings I’d probably want to install a new chain and cogs anyway unless you know they have low miles.