ritzkraft79

i have a Specialized Tarmac SL4 with a Praxis BB. it’s a BSA threaded and the M24 variant. i didn’t have any problems at all but recently it has started to creak. i wouldn’t call it squealing or metallic at all, it kind of sounds like when you are bending a cheap piece of plastic and you get this plasticky creak. only happens after around 40km for some reason. if Hambini has taught me anything it’s because of the BB shell not being formed well, but that’s not really something i can check. before i let someone more qualified take a look at it i might as well diagnose the problem or try to fix it as i usually do things myself. what could be causing the problem? is it a quick fix? do i have to replace the BB? will a shimano BSA BB be any better in not having issues? or is it a frame problem?

dsbrantjr

Do the cheap and simple things first. You might want to swap out your pedals for a known-quiet pair; clean and lube both make and female threads before installing them.

ritzkraft79

i already lubed the pedals, pedal threads, crank threads, chainring bolts, chainset spindle and the BB. only thing i didn’t grease is the BB thread, but that requires that i remove the BB itself and i really don’t want to spend 25 dollars on a specialized wrench just for this BB if i don’t even know if it will fix the problem. Shimano BSA BB wrenches don’t work because Praxis decided to go proprietary and use a different shape for their wrench

primov8

Only the Praxis M30 external threaded bb cups requires their proprietary M30 bb tool. The M24 bsa threaded bb is removal with any external, 16 notch bb tool.

smashndash

Praxis BBs always come loose after a bit of riding. I've had 2 and they both did exactly the same thing. Bike shop says you're supposed to come back in and get it tightened up when it does that.

Thread-together bottom brackets *do not creak* unless you have a god-awful shell.

EDIT: wait it's a BSA bottom bracket? Hm. I'd say it's even more true that it shouldn't creak... but BSA also shouldn't come loose on its own. Regardless, I'd try tightening it first.

cpach

First off--a lot of creaks riders assume are from the BB aren't. For whatever reason everything sounds like its coming from there, and a ton of creaks will clock to crank movement because it's a major shift in stress all over the bike every time you rotate the cranks. Check pedals, saddle rails, quick releases, etc.

If you're pretty sure it's the BB, pull the cranks and see if the bearings are rough at all when turned at hand. If so, you need a new BB. Also check that the external cups are threaded in tightly.

M24 is basically the same thing as SRAM GXP in that it is 22mm on the NDS and 24mm on the drive side, and loads the bearings unevenly. It's runs with worse bearing efficiency at all times and will have worse bearing life than something like a Shimano Hollowtech II setup. I'm genuinely fond of most Praxis products but I'm not sure why they chose to copy such a crap design. One thing you can have done to improve the bearing alignment is to get the BB shell chased and faced, ensuring that the outside faces of the shell are perfectly parallel to one another.

ritzkraft79

it’s an M30, just double checked. it has less notches than a standard hollowtech BSA so i don’t think the tool will fit so i can’t tighten anything. do bike shops have these tools or do they have to buy them in order to fix the BB?

primov8

You'd have to check with your LBS but since several bike manufacturers have gone with Praxis cranksets, it's possible they could have the M30 bb tool. Ask your LBS if they even have a Park Tool BBT-35 since that is specific for Praxis M30/35 bottom brackets.

Crankycrank

I'll put in my 2 cents. As cpach mentioned it's possible it could be something other than the BB. Since you mentioned it has a plastic-y sound and starts after 40km it could be something that is affected by body heat building up such as with the saddle (does it make the sound when you're out of the saddle?) or could be your pedal cleats rubbing or having loose mounting screws. Of course it could be a BB shell needing facing or threads needing tightening and grease or something else with the BB. You can get Praxis tools on Ebay for around $20 which is slightly better than the $25 you mentioned and a good investment for maintenance if you plan on keeping this setup for awhile. M30 Praxis Works Bottom Bracket tool-- Socket for BB30/M 30 ---Spanner/wrench BB | eBay , Praxis Works Single (1) M30 Bottom Bracket Tool TP-3028 Cup Removal/Installation | eBay

ritzkraft79

the bike creaks even without cleats and out of the saddle. since i have pretty much greased every moving part of the bike i doubt it is anything else. i might just buy the wrench and fix it myself

cpach

The tool is common in shops but probably not universal. I had to buy one at my last shop. I'll bet every Specialized dealer has one since they've specced Praxis so often.