Chain length difference between 11-28T and 13-30t cassettes?
03-21-21, 08:52 AM
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Chain length difference between 11-28T and 13-30t cassettes?
I just changed the chain on a bike with a 11-28T cassette and I was thinking about trying a 13-30T cassette. I'm assuming that I would add 2 links to the chain to keep the same relative derailleur "geometry" As I remember I when I set up the 11-28T cassette I went one link long instead of one link short, so I'll try it out as is. I just wanted to check on what the "Theory" was. Thanks
03-21-21, 08:59 AM
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If you are now 1 link long you'll be fine.
03-21-21, 09:14 AM
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People get by with way to long chains and some manage not to suck up their rear DR with way too short chains. So chain length isn't an exact science that necessarily has bad consequences if you aren't exact.
So yes, try it and see. Watch your jockey wheel on the rear DR as you shift through the range and just make certain it doesn't come close to trying to become "one" with the cassette. If so, adjust your b-screw. You don't want the link between the jockey wheel and any cog on the cassette to be nearly flat or nearly perpendicular between them. The links should flow through that gap at an angle.
If you can't get that, the add links or get new chain and start over.
So yes, try it and see. Watch your jockey wheel on the rear DR as you shift through the range and just make certain it doesn't come close to trying to become "one" with the cassette. If so, adjust your b-screw. You don't want the link between the jockey wheel and any cog on the cassette to be nearly flat or nearly perpendicular between them. The links should flow through that gap at an angle.
If you can't get that, the add links or get new chain and start over.
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03-21-21, 01:50 PM
#5
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Do the test in the pic below on the largest ring & cog.
IF you have at least 3 half links "slack", you are good.
IF you have at least 3 half links "slack", you are good.
03-21-21, 03:35 PM
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Bill: for completeness you need a pix of the RD cage as well to show whether the cage is not fully straightened
out by the chain in the 'big-big' position.
out by the chain in the 'big-big' position.
03-21-21, 06:05 PM
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03-23-21, 07:49 AM
#8
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It's always going to safer and more sure to use the standard, don't run chain through rd and do the large large + the extra number of links thing.
Check out the Parks Tools vids.
Check out the Parks Tools vids.
03-23-21, 07:58 AM
#9
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The correct answer is one more link is needed to wrap the big/big, but the minimum change is 2 links, so very carefully try the big/big with old chain to be sure it will work. Better yet, try a new chain with two more links first. If it wraps the big/big and still has tension on the lower section of chain in the little/little you're good. A little lack of tension in the little/little won't hurt.
The chain length formula tells you that every 4 teeth requires 1 inch or 2 links of chain. A perfect combination is a 16 inch chainstay with a big/big combo that's divisible by 4.
The chain length formula tells you that every 4 teeth requires 1 inch or 2 links of chain. A perfect combination is a 16 inch chainstay with a big/big combo that's divisible by 4.
03-23-21, 12:38 PM
#11
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The little/little method makes the chain long enough to fit any cassette within the RD's wrap capacity. It would only be too short if the listed maximum wrap was exceeded. The big/big method makes the chain as short as possible. If the chain is set for a 30T largest sprocket there's no reason to shorten it to use a 25 or 28.
03-23-21, 02:16 PM
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The little/little method makes the chain long enough to fit any cassette within the RD's wrap capacity. It would only be too short if the listed maximum wrap was exceeded. The big/big method makes the chain as short as possible. If the chain is set for a 30T largest sprocket there's no reason to shorten it to use a 25 or 28.
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Life is too short not to ride the best bike you have, as much as you can
(looking for Torpado Super light frame/fork or for Raleigh International frame fork 58cm)
03-23-21, 02:54 PM
#13
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Assuming you're not running the derailleur at or above capacity. It can get even trickier with full-suspension bike operating at capacity. Big-big is safer, but small-small works better for derailleurs operated within their published limits.
