Understanding & Servicing Your BB | PB Tech Tuesdays

[@wallyworld6249]

The amount of knowledge required to be a truly professional bike mechanic is staggering. This video taught me a thing or two. Well Done! In addition to using a high quality anti seize paste I've added 3 wraps of plumbers Teflon tape and it works a TREAT and it seems to really quiet it down for extended periods.

[@abtcup]

Great tip about greasing the inside of the bearing. I always try to just use a light film of grease on the spindle. I need to remove the crank on my new bike, as it was assembled with a bunch of grease around the BB.

[@philipB31]

Thank you. Happy holidays.

[@NanoDex]

Already said this but I want to double down. Don't preload your bottom bracket much at all. Eliminate any play and go no farther! Its a sure way to wear it out in 2 big rides. Ive done this 4x before I understood my problem. Rage was large. Don't buy the special shimano hollow crank star tool, just use your finger. The tool I guarantee you will over-tighten it. 100% agree on lube. I will never be sold on press fit. Ever. Threads are always better.

[@exothermal.sprocket]

Bearings like specific clamping pressure. Not excessive. Not insufficient. Specific clamping pressure. Bearings will shed excessive grease. Bearings need enough grease. Not excessive grease. Not insufficient grease. Simple enough grease. Bearings will overheat with too much grease. Bearings will fail with too much clamping force. Bearings will skid (malfunction) without enough clamping force. It has to be done right. If it is done correctly the bearings should have an appreciably long life.

[@janeblogs324]

Great, but cranks never spin at more than 100 rpm, so load them up

[@exothermal.sprocket]

@@janeblogs324 While you need more RPM to create the heat from excessive grease, you still get a lot of drag with excessive grease even if it doesn't heat up. Bearings don't require to be drown in grease to function as designed.

[@janeblogs324]

@@exothermal.sprocket BBs with extra grease don't drag much at all. The BB shell FILLS with water that drips down the seat post. Some frames don't feature a drainage hole so the water has to flood the crank and weep past the inner race. Obviously you've never looked at or installed a new shimano hollowtech BB, they are overflowing with neon green grease for a reason. The grease stops water entering the bearing races that are made of steel that rusts.

[@exothermal.sprocket]

@@janeblogs324 Take it easy with the "obviously" statements, as they are 98% meant to be condescending. So far I've had a decent discussion. Is it also obvious I have a mechanical engineering occupation? I don't need to work on bicycles to understand how various types of bearings function or how enclosed mechanisms with grease need to function? No that's not obvious. There are things that apply in engineered devices across industries because physics and mechanics are the same.

[@janeblogs324]

@@exothermal.sprocket these BB bearings are only sealed on the outside, any extra grease is pushed out of the bearings race. You literally can't over fill them

[@Tytyrytkataaa]

My bike’s got Sram GXP on it and i remember it creaked once after i serviced it. Turned out that i hadn’t tightened one of the bearing cups enough to spec which was 40 newtons. So i had to get a torque wrench

[@Mo.Jo.MTB_101]

I personally never had any issues with a creaking BB... I think if installed well pressfit works good or maybe I was have been lucky so fare.. What I find helpful for a quiet bike is a clean drivetrain... In german winter weather I give it a good clean (chain and cassette of) about once a week as I hate the noise and of shifting of a dirty drivetrain...

[@ostankovalex1176]

had a Cube, 2 Trek remedies 18 and 23, RM altitude - all pressfit and creek free

[@woduk]

I’m in uk so have horrible weather year round, hope I’ve used for years pay more and get something better made

[@Live_Loam_Lap-po4qt]

Threaded BB's and SRAM DUB BB's. $34.00. Easy swap. Cheap to replace. Never buying a bike with Press Fit again.

[@WannaJumpBikes]

Ever had a press fit but from what i heard its stopped me from buying bikes with them

[@steven.9263]

9 times out of 10 someone's BB is totally fine, but they heard an unrelated creak and loose their mind. Quit servicing things that don't need service and MTB is 100x more enjoyable.

[@benphillips1149]

​@@steven.9263 best way to know your bb needed replacing is putting in a new one and suddenly being able to pedal way easier

[@jakubnosek3220]

I'm always applying a lot of grease on the axle to protect the bearings from water never had creaking bb

[@MrChadLedford]

SRAM dub system is so good. I prefer shimano drivetrains, but don't run them because of the crank system. If those clinch bolts aren't torqued perfectly you say goodbye to that crank. Just my anecdotal experience. Maybe i suck.

[@janeblogs324]

You can't inspect the bearings in the BB once you've removed the cranks. You need to push side to side & push/pull the pedals together to identify crank play. You need to drop the chain & do a spin test listening for rumbling through the bike frame, any vibration means the bearings are pitted but adding grease will mask this. You need to prop the bike on the side and tap the cranks to spin them 1° at a time, if they always stop at an exact angle then the bearing races are "indexed" meaning they have dents in them an they're hexagons now instead of round. When tightening the crank preload bolt do a crank freespin test, you want the maximum free rotations possible with no crankplay, tighten the bolt 20° at a time between spins till you get 1 less rotation, then back it off 20°.

[@SergejGrabun]

I have DUB SRAM and I it got all dirty and gunky inside (I opened it up) very quickly, like 400-500 kms. I would imagine they should be more dirt/mud tight than this. Bought new, will install, see if maybe factory one was somewhat imperfect (did 2500km this year on that 'bad' one, did not want to install new for the winter). If this new serves me little again - Will have to buy aftermarket bearings

[@AsheMorrissette]

What kind of grease or lube do you use on the crank spindle

[@rjoly8029]

Myself have found that the chainring side crank bolt on clinch style arms becomes loose and causes creaking. For sure over torqued aluminum BB shells get wonky and stress the bearing race face 😂😂

[@tom6493]

3:13 wrong. Whether you grease the threads or not, is down to the manufacturers torque specs. Typically torque specs; unless otherwise stated, are for DRY threads and if you grease them when you shouldn’t, you risk over tightening and damaging the threads/components.

[@TE_53349]

would creaking whilst pedalling under load be subject to a worn or damaged bottom bracket?.

[@grundle.chunder]

Nothing wrong with press fit, really, The problem is/was actually that it requires higher quality frame manufacturing to ensure proper alignment. As long as you can get that, the performance/benefits are there.

[@nathantoney.1501]

What about ebike’s? Seems like they work until they don’t

[@LinkinRG10]

Good luck removing Sram cranks with gajillion NM torque spec at home

[@daved2023]

Strap non-drive side to rear triangle and then loosen drive side. Easy to do when strapped down tight.

[@Henry-Quinney]

2 gajillion I would say

[@woduk]

If frames were made accurately then press fit wouldn’t be an issue, ask hambini about it 😂

[@ianiscaratti4924]

Servicing a 25$ Shimano bb is a nobrainer for me. Chris King, Ceramic Speed or Kogel is a different story but just ride it till death an exchange it if you value your time.

[@francisdee9955]

👋

[@janeblogs324]

1: You can't inspect the bearings in the BB once you've removed the cranks. You need to push side to side & push/pull the pedals together to identify crank play. 2: You need to drop the chain & do a spin test listening for rumbling through the bike frame, any vibration means the bearings are pitted but adding grease will mask this. 3: You need to prop the bike on the side and tap the cranks to spin them 1° at a time, if they always stop at an exact angle then the bearing races are "indexed" meaning they have dents in them an they're hexagons now instead of round. 4: When tightening the crank preload bolt do a crank freespin test, you want the maximum free rotations possible with no crankplay, tighten the bolt 20° at a time between spins till you get 1 less rotation, then back it off 20°.