Ultegra 6800: 46/36 to 46/34?
05-22-16, 11:08 AM
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Ultegra 6800: 46/36 to 46/34?
I just got a bike with a Ultegra 6800 46/36 crank, and I was wondering if I would have any issues swapping the 36 chainring for a 34 chainring.
Does anyone here have experience running this setup? Any shifting issues?
Does anyone here have experience running this setup? Any shifting issues?
05-22-16, 11:38 AM
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I can't say that I've tried this with a 6800 crank, but I've changed both of my 46/36 cranks (a FSA Gossamer and a Shimano CX-50) to 46/34 with no issue. I can see no reason why you wouldn't have the same success.
05-22-16, 11:50 AM
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I only see one replacement 6800 46T ring for sale online, leading me to believe they use the same one with 36T or 34T inner rings. If it were otherwise, I'd expect to see separate "A" and "B" type rings for sale that were specific to 36T or 34T. 
05-22-16, 11:51 AM
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Thanks for the comments. I figured if Shimano doesn't sell the 46/34 combo together there must be a reason for it.
Looking forward to hearing from someone who has a 6800 crank and FD with 46/34.
Looking forward to hearing from someone who has a 6800 crank and FD with 46/34.
05-22-16, 11:56 AM
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I figured if Shimano doesn't sell the 46/34 combo together there must be a reason for it.
05-22-16, 12:47 PM
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Provided you can bolt it up and it doesn't exceed your derailleurs' specs, it should work just fine. The innermost chainring doesn't need any pins to lift a chain from a smaller ring nor gates to facilitate shifting to a smaller ring, so any ol' ring -- even one without any special shift aids -- will work.
05-22-16, 07:41 PM
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Bump for the Sunday night crowd.
Thanks
Thanks
05-23-16, 08:09 AM
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Shimano doesn't sell a lot of things for no reason. They also tell you that you can't do a lot of stuff that because it won't work. But, in my experience at least, Shimano severely underestimates the ability of their equipment. Their whole "MB", "MA", "MD" thing is to get you to buy new components when you don't really need to. At the very least, I'd get a 34 tooth inner (you don't even need to use Shimano's rings at all) and try it. If it doesn't work, you're out a few bucks for the ring.
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05-23-16, 08:14 AM
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Oh wait -- perhaps I spoke too soon. Looking through the Universal Cycles page, I'm seeing that the 52T, 46T, and 36T are listed as "MB" type, the 50T and 34T are listed as "MA" type, and the 53T and 39T are listed as "MD" type. So it seems that 46/34 isn't an "approved" combination, but I would be somewhat surprised if it didn't still work.
The quickest way is to drop the chain onto the BB, remove the 4 bolts from the back, remove the big ring, then carefully guide the inner ring past the arms and over the crank so you don't scratch anything. Reverse to put it back together. Make sure inner ring is facing the right way, there should be recesses where the bolt heads sit.
There are no shifting helper bits on these small rings, They're pretty much identical except for the tooth count.
I follow the Shimano engineering documents pretty closely, but find no problem ignoring the suggested marriage to the big ring.
Pro Teams are mixing and matching any combo of big ring and small ring also.
Last edited by andr0id; 05-23-16 at 08:20 AM.
05-23-16, 08:26 AM
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6800 cranks have a single bcd so all chain rings are interchangeable so you can swap 36 for 34. You have to use Shimano rings though.
05-23-16, 09:29 AM
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Thanks for the comments, I guess I'll order up a 34T chainring and give it a shot!
05-23-16, 09:51 AM
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Shimano Ultegra FC-6800 11-SPD Chainring > Components > Drivetrain > Chainrings | Jenson USA
It's not an expensive experiment!
05-23-16, 11:12 AM
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05-23-16, 08:32 PM
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At $10 for the chainring:
Shimano Ultegra FC-6800 11-SPD Chainring > Components > Drivetrain > Chainrings | Jenson USA
It's not an expensive experiment!
Shimano Ultegra FC-6800 11-SPD Chainring > Components > Drivetrain > Chainrings | Jenson USA
It's not an expensive experiment!
I'll try to remember to report back on how shifting of the 46/34 is compared to the 46/36
05-26-16, 02:35 PM
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Update: Installed the 34T small chainring and went for a 3 hour hilly ride today. Shifting is perfect. The 46/34 combo in Ultegra 6800 works great.
05-27-16, 09:56 AM
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05-27-16, 09:57 AM
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08-30-17, 07:22 AM
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Jut got my 34T ring today
Will install it over the weekend and report.
Also replacing the stock 105 11-32 cassette with a SRAM PG-1170 11-36 cassette.
Also replacing the stock 105 11-32 cassette with a SRAM PG-1170 11-36 cassette.
01-29-20, 07:29 AM
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I run Ultegra 6800 46/34T setup on all three of my bikes without problem.( Old man tired legs ) The only slight issue is getting the front mech low enough for the 46T chainring but they work faultlessly.
01-29-20, 09:21 AM
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50/33 here. works perfect. this is on a 5 bolt 110 bcd double crankset, both bikes, one FSA and one XLT Race 8, running shimano/FSA 50 toofus with the Zephyr 33 inner...all specs usually can be exceeded as you have found out. manufacturers playing safe...going to experiment with 11/36 soon, running 11/34 on both presently....
01-29-20, 11:43 AM
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This is a 2+ year old thread aka ZOMBIE-
01-29-20, 12:59 PM
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https://www.peterwhitecycles.com/ta-...x110chainrings
https://www.peterwhitecycles.com/str-rings.php
Order them from Europe for more reasonable prices.
01-30-20, 05:19 AM
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It shouldn't be a problem as long as your RD can take the tooth difference.