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Chain sizing question

959 views 4 replies 3 participants last post by  Fireform 
#1 ·
Here is my situation. I live on the flats and my main ride is set up with 11-23 on the back and 53-42 on the front, which serves me perfectly well. However, I have a ride coming up which involves a lot of climbing, and I'm thinking about switching to a compact 50-34 on the front for this ride. The timing of this ride will more or less coincide with an expected chain change. So here is my question: if I size the chain via the small-small method to the 50-34 crankset, will my chain be too short when I put the 53-42 back on? The mech is 7900 mechanical.

Thanks!
 
#2 ·
Do you have the compact crankset with you now?

If you do, you can just try to swap it over to see how your current chain length fit over the compact. I would think it will be a bit long and so logically to answer your question, the chain will be short.

Why don't you re-size your old chain to the compact, use it for the ride and keep the new chain for when you swap back to your 53/42.
 
#5 ·
Why don't you re-size your old chain to the compact, use it for the ride and keep the new chain for when you swap back to your 53/42.
I think this is the winning entry. Thanks.
 
#3 ·
Here is my situation. I live on the flats and my main ride is set up with 11-23 on the back and 53-42 on the front, which serves me perfectly well. However, I have a ride coming up which involves a lot of climbing, and I'm thinking about switching to a compact 50-34 on the front for this ride. The timing of this ride will more or less coincide with an expected chain change. So here is my question: if I size the chain via the small-small method to the 50-34 crankset, will my chain be too short when I put the 53-42 back on? The mech is 7900 mechanical.
53/11 "serves you perfectly well"? I'm VERY impressed. That's over 37 mph at 100 rpm.

As to the chain length question: you will get a chain 4 links (2 inches) longer when you size it small-small on the 42 instead of the 34. You should be able to figure out pretty easily whether that is a problem.

Are you going to change the cassette as well for this climbing ride? If not, you could just go with a cassette with a 28 or 29t large cog and get the same ratio as a 34/23. It would be much cheaper. Is the smallest ring your current crank will take a 42? If not, going to a 39 (or perhaps 38 if possible) would get you almost half-way to the 34, and combining that with a cassette with a 27 large cog would be the same low gear as a 34/23.
 
#4 ·
I consider it a feather in my cap that you're impressed, Kerry, but 37 is not unheard-of. I hit 40 in a crit this spring and it wasn't even the sprint.

I am, of course, going to change cassettes. A teammate who did this race last year, and who is a better climber than I, did it on 39-25 and struggled badly. I have a 28-11 that will probably make the trip.
 
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