Chainrings: 34-52 with Ultegra R8000?

[MRC01]

My road bike has a low gear 34-34 and I love the 1:1 ratio since I hit 15-20% grades on every ride. However, the top gear is 50-11 which is shorter than my last bike, which was 52-11. It seems a small difference, only about 4%, but I actually do notice it. Occasionally I go fast enough on downhills that I spin out in the 50-11.

So I'm considering replacing the 50 with 52 on my R8000 cranks. I've read that Shimano doesn't officially support this, yet everywhere I've read, people say it works just fine. What say you all?

The only reason I ask is because those chainrings cost $150-$200 ?!?! I must be getting old because that seems ridiculous. If it were less expensive I would just buy the 52, try it, and toss it into my used bike parts bin if it didn't shift well.

 

[supton]

On those hills where I spin out in 52x12 I always ask myself, what could possibly go wrong? as I get older I am thinking that this is an issue I should not fix.

I know nothing about it, but what is the FD? want to say that they are sculpted to match the big ring. might not like the bigger diameter.

 

[MrQuackers]

150 clams for a chainring? What in the wide world of sports?

 

[BISCUT]

50 to 52 with Ultegra should work fine. If me, I'd give it a go.

 

[MRC01]

50 to 52 with Ultegra should work fine. If me, I'd give it a go.

The real issue is the difference between the small & big chainring. Shimano makes a 52 but it's supposed to pair with a 36. And they make a 50 that pairs with the 34. The question is whether 34-52 works, as it's a bigger jump from small to big.

 

[Brons2]

How much chain does the RD wrap, as well?

$150 for a chainring? This is why I use the old stuff. Sugino square taper cranks. Works fine at my output level.

Have you looked for an aftermarket equivalent? Sometimes you can find more options on the European parts sites, and they often ship to the US.

 

[MRC01]

How much chain does the RD wrap, as well?

The current 50-34 front and 34-11 rear push the chain & rear derailleur to its limits. However, I'm not concerned about that because I don't use the extreme gears. What I do question is whether the front derailleur can handle shifts across a bigger chainring size difference.

 

[BISCUT]

The real issue is the difference between the small & big chainring. Shimano makes a 52 but it's supposed to pair with a 36. And they make a 50 that pairs with the 34. The question is whether 34-52 works, as it's a bigger jump from small to big.

I am not running this but I do have knowledge of others that have/are. Part of success with this arrangement IMO is the skillset to work the chain with the front D for a seamless transition. Anyone with enough knowledge to benefit from what you'd like to do is certainly akin to planning your shifts out at the right time. My 2 cents is it would work but that is a guess in the end.....

Please let us know how it goes if you try it out.

 

[853okg]

It will work, but it certainly isn’t ideal. I wouldn’t do it for such a tiny gain. A 50x11 is a really big gear already. You’ve already got a 16t jump, which is huge. Do you have a compact FD now?
Assuming you have a 110mm BCD on your crank I’d buy an aftermarket chainring for sure if I were going to try this, which I wouldn’t. Either develop more leg speed or engage your Georgia overdrive.

 

[MRC01]

My riding buddy pulled a set of Dura-Ace cranks from about 3 years ago out of his used parts bin. The big DA chainring doesn't fit Ultegra due to a different contour of the cosmetic outer plate (the bolt pattern etc. does match), so I just swapped the cranks and readjusted the FD, and installed the 34T from my Ultegra onto the DA crank. I now have a 34-52 to ride for a while and see how I like it.

 

[MRC01]

Update: the 34-52 works perfectly. I tried to get it drop the chain on today's test rid: slam it up and down, shift front & rear simultaneously, it doesn't miss a beat. The shifting is just like with the 34-50.

If Shimano doesn't officially support this, I imagine it's because 34-52 only works when everything is set right, and they know some bikes aren't set right.