Compatible fit?
06-22-22, 07:21 PM
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Compatible fit?
Hello everyone and thanks for your time to read over my question. I am replacing the bottom bracket for my Trek and need a new Shimano BB ES-25. Question being, the old one is 118mm when I had a 3× on it but now I am looking to keep the same cranks but wondering if I could use the 113mm BB for my 1x chainring setup? I understand that the clearance will be narrower but would that work? Btw, the Bike is a 2013 Trek Mamba, 29er, XL frame if that changes anything. Thanks for the feedback.
06-22-22, 08:51 PM
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Will you be using the current crank? Which ring position will you use? What ring size will you use? how much splay out does your chain stays have?
The common way to figure this out is make some choices on ring used and test fit in either crank spider tab location and see what stay/ring clearance you have as well as the chainline resulting. Then make some "adjustments" to the BB axle length given the prior test fit and measurements. Andy
The common way to figure this out is make some choices on ring used and test fit in either crank spider tab location and see what stay/ring clearance you have as well as the chainline resulting. Then make some "adjustments" to the BB axle length given the prior test fit and measurements. Andy
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06-23-22, 06:57 AM
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Thanks for reply Andy. I'm currently changed over to a 1x Oval 32T to run the single chainring but I noticed by taking the 3x it created a gap where the seal is to the bb. Before I shorten my chain I was going to change to a new bb because of the creaking crank pedal strokes.
06-23-22, 10:56 AM
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Procedurally, best to first install the new crank (or the new ring installed onto the old crank) onto the old bottom bracket, evaluate the chain line, then buy a new bottom bracket accordingly to move the chain line (either inward or outward) to line up with the center of the cassette.
Converting Trek FX2 to 1x - Bike Forums
See what I did starting from post #17.
Converting Trek FX2 to 1x - Bike Forums
See what I did starting from post #17.
06-24-22, 02:34 PM
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if it'll allow everything that is rotating to clear (keep from rubbing) then it should be fine. You'll need to do a mock-up test fit & simulate the shorter BB for potential clearance impediment issues.
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