# 52/34 chainrings ok?



## jmitro (Jun 29, 2011)

on my 110BCD FSA crank, I have the option of installing 50 or 52T big chainring and 34, 36, 38 small chainring. To optimize gearing for both climbing and for flats (all of my cassettes are 12-25 ten speed), I would like to use a 52 big chainring and 34 small chainring.

Is this mechanically feasible or is it too big a difference in tooth count?


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## danl1 (Jul 23, 2005)

jmitro said:


> on my 110BCD FSA crank, I have the option of installing 50 or 52T big chainring and 34, 36, 38 small chainring. To optimize gearing for both climbing and for flats (all of my cassettes are 12-25 ten speed), I would like to use a 52 big chainring and 34 small chainring.
> 
> Is this mechanically feasible or is it too big a difference in tooth count?


It's too big a difference for decent shifting, but perhaps more importantly, it's unlikely the rings will be appropriately paired. Modern chainrings are designed to go together, so that the ramps, pins, and other shifting aids align properly. If they aren't paired, as the chain tries to move from one ring to another, it won't find itself meshing properly with the new ring, slowing shifts and increasing the chances of problems like dropped chains or broken teeth.

If you believe you need a 52x12, a 50x11 is a bit taller - so an 11-25 cassette on a 50x34 will get you to the same place. Changes the gaps a bit, but better overall than what that large a front change would do to you, IMO.


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## jmitro (Jun 29, 2011)

Ok that makes sense.
Thanks!


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## LC (Jan 28, 2004)

16T difference is already pushing it to the limit. 11T cog is the best solution, but 52/36 chainrings would work although much more money.


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## svard75 (Jun 10, 2011)

I went with a 52/36 chainring and 12-25 out back and find im spinning high rpms at 60kph on descents. Climbs are decent in the rear ring just below the largest ,whatever size that would be. Do they make an 11-25 cassette?


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## Cat 3 boy (Aug 20, 2002)

You are aware that your cadence at 60kph in 52x12 is only 110 rpm, 

Personally I'd stick with the 12 & no big jumps between ratios as you have at the moment.


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## svard75 (Jun 10, 2011)

Cat 3 boy said:


> You are aware that your cadence at 60kph in 52x12 is only 110 rpm,
> 
> Personally I'd stick with the 12 & no big jumps between ratios as you have at the moment.


feels like a lot more. My legs are really big from mashing on my MTB. Just learning to spin.


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## Kerry Irons (Feb 25, 2002)

*Coasting*



svard75 said:


> I went with a 52/36 chainring and 12-25 out back and find im spinning high rpms at 60kph on descents. Climbs are decent in the rear ring just below the largest ,whatever size that would be. Do they make an 11-25 cassette?


At that speed, you are almost certainly ahead to get into a tight tuck and coast. Even in a race against somebody with a 53/11 you probably could get into their slipstream and keep up without pedaling.


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## svard75 (Jun 10, 2011)

Kerry Irons said:


> At that speed, you are almost certainly ahead to get into a tight tuck and coast. Even in a race against somebody with a 53/11 you probably could get into their slipstream and keep up without pedaling.


I thought road riding was all about constant cadence.

Tbh I actually enjoy this setup. On the flats, sans headwind, its quite easy to maintain 40-45kph in 52-12. I also found the ratios are so close you can almost always find a sweet spot on any grade.


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## SystemShock (Jun 14, 2008)

svard75 said:


> Do they make an 11-25 cassette?


They do. Though you would be giving up the 16t cog, if that matters to you.
.


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## speed metal (Feb 8, 2007)

I know a local rider that runs a SRAM 52/34. He likes it, said he has to be carebul about cross-chaining.


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