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Bigger cog or smaller chain rings?

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Bigger cog or smaller chain rings?

Old 08-24-19, 10:27 AM
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jackb
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Bigger cog or smaller chain rings?

I have a 2018 Domane SL5 disc which I like very much. It runs 50x34 chain rings in the from and an 11x32 cog set. I would very much like a a lower gear for getting up the really big hills that I frequently ride. Would it be better to move to an 11x34 cog set, which I know Shimano makes, or would it be better to shop around to find 46x30 chain ring combo, which I hear is available. The bottom bracket is the Trek BB90 and the bike has the 105 group set. Any ideas? Thanks.
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Old 08-24-19, 11:05 AM
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Going from a 32T to a 34T in back won't help much. My vote is for a 46/30 crankset.
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Old 08-24-19, 04:10 PM
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Adding two teeth to a 32, thatís a 6.25% difference.
Removing 4 teeth from a 50, thatís an 8% difference.
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Old 08-24-19, 05:31 PM
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Can't get to 46x30 just by changing the rings on the crank. As noted above by ThermionicScott, gotta change crankset.
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Old 08-24-19, 06:02 PM
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IMO if you need lower than 34/32, you need a triple - there's already a lot of compromise in that gearing, and a triple eliminates it. Pity they're not really a thing anymore, and in this era when everyone wants lower gears, that's just dumb.

If you had Campy levers, you could do it with a crankset and FD, plus chain and long cage RD. Otherwise SOL.
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Old 08-24-19, 08:55 PM
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Originally Posted by dabac View Post
Adding two teeth to a 32, thatís a 6.25% difference.
Removing 4 teeth from a 50, thatís an 8% difference.
But removing 4 teeth from a 34 tooth chainring is an 11.8% difference.
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Old 08-24-19, 08:59 PM
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Originally Posted by Kimmo View Post
IMO if you need lower than 34/32, you need a triple - there's already a lot of compromise in that gearing, and a triple eliminates it. Pity they're not really a thing anymore, and in this era when everyone wants lower gears, that's just dumb.

If you had Campy levers, you could do it with a crankset and FD, plus chain and long cage RD. Otherwise SOL.
+1 Triples rule. I'm thankful I learned dinosaur shifting while they still ruled the earth. (Downtube shifters; those stone age devices that work with anything.)

Ben
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Old 08-24-19, 09:33 PM
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Originally Posted by delbiker1 View Post
Can't get to 46x30 just by changing the rings on the crank. As noted above by ThermionicScott, gotta change crankset.
Sure you can
https://absoluteblack.cc/oval-road-c...-for-110-4bcd/
but it ain't cheap. I run that on my road/gravel bike and love it. GRX wasn't around when I bought it though and at this point I would probably go for a GRX crank and new FD instead, probably the 48/31. The 46 is fine but the 48/31 would keep more of that top end without really making climbing any different.
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Old 08-24-19, 09:38 PM
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if you have 110 bcd crank, 46/34 works well for me, able to stay on the big ring most of the time for increased efficiency. unless you really want to push your luck down hill, 46/11 is plenty
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Old 08-25-19, 01:12 AM
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Originally Posted by Canker View Post
Sure you can
https://absoluteblack.cc/oval-road-c...-for-110-4bcd/
but it ain't cheap. I run that on my road/gravel bike and love it. GRX wasn't around when I bought it though and at this point I would probably go for a GRX crank and new FD instead, probably the 48/31. The 46 is fine but the 48/31 would keep more of that top end without really making climbing any different.
That's a clever way to utilize the new 4-bolt mounting arrangement!

I had round rings on a smaller BCD in mind, of course.
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Old 08-25-19, 02:19 AM
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Take look at the new GRX components from shimano. There is a 46/30 crank (For this you need the FD as well). Combined with a 11-34 cassette you have good gear reduction.

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