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I have an older Wabi Classic cycle which comes with TH Industries BB-7420AL 68/103 that seems to creak. I believe its called squared tapered. Its a single speed. Missing Cranks

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I want to change the Bottom Bracket and Crankset to a new Shimano/ Sram with I think its called external threads? How do I buy both?

Can it be changed?

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    You should read this.
    – Batman
    Commented Sep 5, 2017 at 3:36
  • I'd like to reiterate that this may not be the solution to your creaking problem.
    – Criggie ♦
    Commented Sep 6, 2017 at 8:14
  • I agree, i still want to change it to a lighter more cooler crankset!! its also a single speed steel bike and with no chain, spinning crank with no pedals creaks - its likely that is the cause
    – nolawi
    Commented Sep 6, 2017 at 19:28

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Yes it can be changed - you need a cartridge BB that has the same measurements. Based on your photo its a 68mm english threadded BB with square taper crank fitting.

The only thing I can't tell you is the overall length of the BB axle. You'll need to know this to get the same effective chainline when installing your right crank. Likely numbers are 103mm, 110mm, 113mm, 116, 118, 123.5, 124.5 or 127.5mm.

You need a 103mm one so the front chainring ends up the same distance out from the centerline of the bike. This is the chainline and getting it wrong means bad shifting, chain drops and chain suck.

Thing is, you say it creaks. Changing the BB might resolve that, or it might not. If the BB spins smoothly, without play or crunch, then its less likely to be the root cause of your creak.

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    TH BB-7420ST, 68/103 sealed is the one i currently have.
    – nolawi
    Commented Sep 5, 2017 at 4:55
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    Although single speed, based on your answer do not worry about shift
    – nolawi
    Commented Sep 5, 2017 at 18:26
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    every crankset is designed with a certain spindle length in mind. You say you're missing the cranks. So if you stick with square taper, when you pick your cranks you'll have to see what spindle length it needs. If it's 103, you're fine with the current BB. If not, you'll need to get a new BB to match it.
    – Noah Sutherland
    Commented Sep 5, 2017 at 19:36
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You can indeed replace the square taper cartridge with an external bearing bottom bracket and fit new cranks.

Shimano's system is HollowTech II, SRAMS's is GXP, there is also FSA's MegaExo. I believe that the bottom brackets and cranks of each of these systems are not cross compatible.

Note that many bottom brackets are labeled as either 'road' or 'MTB'. Road brackets are typically for 68mm wide BB shells while MTB brackets are typically for 73mm shells.

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  • I think all the external BBs I've seen came with spacers to put in to make them fit the different width shells. Usually a 68mm shell will need a spacer on both sides, a 73mm shell will need NO spacers and a 68mm with e-type derailleur will need a spacer on just the non-drive side.
    – Noah Sutherland
    Commented Sep 5, 2017 at 19:33

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