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Changing crankset for better climb - 50/34 to 46/30

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Changing crankset for better climb - 50/34 to 46/30

Old 10-30-19, 08:18 AM
  #1  
richard.susanto
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Changing crankset for better climb - 50/34 to 46/30

Fellow gravel riders, apology for the basic question here.

I've been using the Shimano Ultegra FC-R8000 50/34 crankset throughout the summer with my new gravel bike (the Canyon Grail CF), and found it not sustainable for my type of riding. I ride mostly on gravel/dirt roads in western Illinois (the driftless region) with multiple long steep climbs.

Talking to a couple of friends, they recommended that I change my crankset to the 46/30 or the 48/32. Both are available now from the Shimano GRX line.

Would like to get your input on this plan, as well as, on the parts and tools that I need to buy to get it replaced. Also, since I've never done it before, is it better to just ask my LBS to do it.

Thanks,
Richard

Last edited by richard.susanto; 10-30-19 at 09:30 AM.
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Old 10-30-19, 08:44 AM
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You don't have to buy a new crank, you can just replace the existing rings to 46/30
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Old 10-30-19, 08:48 AM
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Originally Posted by Elvo View Post
You don't have to buy a new crank, you can just replace the existing rings to 46/30
That's not going to work since the crank has 110 bcd chainrings which means that the smallest you can get is a 34.
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Old 10-30-19, 08:52 AM
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I ride as often as I can in the driftless region as well. I ride older bikes generally with a triple but end up with low gears similar to what you'd get with a 46/30 or 48/32.

That change makes sense particularly since you have considerable experience riding in the area and you know that the current gearing is not working for you.

Changing out the BB is not difficult and there are youtube videos you can watch. Your call but I'd vote for doing your own work.
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Old 10-30-19, 09:33 AM
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Originally Posted by bikemig View Post
That's not going to work since the crank has 110 bcd chainrings which means that the smallest you can get is a 34.
There are 48/32 and 46/30 rings for 110 bcd
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Old 10-30-19, 09:40 AM
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Originally Posted by Elvo View Post
There are 48/32 and 46/30 rings for 110 bcd
Sure, if oval rings that make the effective gearing higher than the nominal gearing are acceptable. The industry really needs to let go of 110 BCD for this stuff...
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Old 10-30-19, 09:40 AM
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Originally Posted by Elvo View Post
There are 48/32 and 46/30 rings for 110 bcd
I stand corrected. I read the description for the crank and the lowest you can go with shimano rings appears to be 34 but with the 4 arm cranks there are apparently smaller rings available from third parties.

It's not clear from this thread that you can go as low as 30 but apparently you can get to 32.

110BCD 32t small chain ring?
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Old 10-30-19, 09:47 AM
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110 bcd 46/30 ebay

bikinGreen CNC Chainring 46/30T BCD 110mm 5 Arms 9-11Sp Road Cyclocross Touring

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Old 10-30-19, 10:18 AM
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Originally Posted by wsteve464 View Post
110 bcd 46/30 ebay
bikinGreen CNC Chainring 46/30T BCD 110mm 5 Arms 9-11Sp Road Cyclocross Touring
Looks like they use skinny bolts to get around BCD limitations on that one. I'll pass.
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Old 10-30-19, 10:40 AM
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The switch to GRX makes sense and you know Shimano cranks and rings will work flawlessly. You can probably use your existing bottom bracket but reports are that you will need the GRX front derailleur as well.
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Old 10-30-19, 11:06 AM
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@richard.susanto @shelbyfv


I've been using Shimano's 46/30T GRX crankset with an otherwise Ultegra (Di2 6800) drivetrain (and bottom-bracket) since the week GRX was released. I had to adjust the front derailleur to the full extent of the H-limit screw adjustment range. It works fine (thankfully, as replacing the Di2 front derailleur would have necessitated replacing the rear as well).

Check your current setup. If you can adjust the front derailleur cage outboard by 3mm or more, you should be fine. The only tool you need to take off and put on a Shimano crankset is a hex wrench. Proper torque on the pinch-bolts is important. Shimano also supplies (or sells for $3) a cheesy plastic insert for finger-tightening and extracting the crank; you will probably want that as well. Finally, you will likely need to shorten your chain one or two links.

FWIW, I've used this with both an 11-34T ultegra cassette and an 11-36T SRAM cassette. Both work well, even though my rear derailleur is conservatively rated to 32T max.

Last edited by Cyclist0108; 10-30-19 at 11:18 PM. Reason: answered the rest of Richard's question about installation
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Old 10-30-19, 11:35 AM
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Love my 46/30 FSA SL-K. I'd do it for the gearing, particularly if you have hard sharp hills. I've thought of getting a 48/32 ring setup as well for a bit higher gearing and easier rides.

The GRX cranks have a different chainline, as already mentioned
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Old 10-30-19, 12:20 PM
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Buy a Shimano GRX crankset or a Praxis crankset(Zayante or Alba). If you buy Praxis from them direct, you can call them and request 48/32 or 46/32 and you can also select the BB tool that works best for you.
I would go for Praxis 46/32 personally. I have a Shimano 46/34 crank right now and like the 46t large ring since it is plenty of gearing for me even on roads due to the larger sized tires. And the closer the rings are in terms of tooth count, the faster/easier shifting is.

With Praxis you wont have to change your front derailleur. With Shimano GRX you will most likely(but not for sure) use a GRX front derailleur since the chain is pushed out a couple millimeters from regular road positioning.



As for all the discussion in the thread about a 30t ring being put on a regular Shimano crank, besides oval shaped Absolute rings, I am not aware of another option. Absolute rings will cost you $220 for a 46 and 30 combo. Thats absurd- just buy a new crank at that point. A GRX is about $220 and a Zayante is about $250.
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Old 10-30-19, 12:25 PM
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Originally Posted by ThermionicScott View Post
Looks like they use skinny bolts to get around BCD limitations on that one. I'll pass.
That ^^^^^. Rube Goldberg at best.
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Old 10-30-19, 11:10 PM
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What's the lowest gear on your cassette in the rear? You could maybe just replace that with maybe a 11-36 and add a Wolf-Tooth Roadlink if needed. Might be cheaper and easier that changing your crank.
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Old 10-31-19, 01:06 PM
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Hi Scott,

Many thanks for the input. It looks like I have almost a similar setup as you, albeit mine is the mechanical Ultegra R8000. Let me buy the GRX 46/30 crankset and start from there.

Richard

Originally Posted by wgscott View Post
@richard.susanto @shelbyfv


I've been using Shimano's 46/30T GRX crankset with an otherwise Ultegra (Di2 6800) drivetrain (and bottom-bracket) since the week GRX was released. I had to adjust the front derailleur to the full extent of the H-limit screw adjustment range. It works fine (thankfully, as replacing the Di2 front derailleur would have necessitated replacing the rear as well).

Check your current setup. If you can adjust the front derailleur cage outboard by 3mm or more, you should be fine. The only tool you need to take off and put on a Shimano crankset is a hex wrench. Proper torque on the pinch-bolts is important. Shimano also supplies (or sells for $3) a cheesy plastic insert for finger-tightening and extracting the crank; you will probably want that as well. Finally, you will likely need to shorten your chain one or two links.

FWIW, I've used this with both an 11-34T ultegra cassette and an 11-36T SRAM cassette. Both work well, even though my rear derailleur is conservatively rated to 32T max.
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