Why do bottom brackets hate me?

[TwoWheelsDC]

@hozn 161540 wrote:

Ah, very good.

I think you could piece together the bearing extractors and drifts from their site (or extractors + universal bb press?) for less than the Enduro tool unless you already have the tools you need for that?

I have a press and the necessary drifts…I’d just need to get an extractor when the time comes.

[hozn]

@TwoWheelsDC 161544 wrote:

I have a press and the necessary drifts…I’d just need to get an extractor when the time comes.

Gotcha. Bear in mind it is possibly two extractors if SRAM (the NDS bearing is smaller ID).

[TwoWheelsDC]

@hozn 161546 wrote:

Gotcha. Bear in mind it is possibly two extractors if SRAM (the NDS bearing is smaller ID).

Because of course…

[Vicegrip]

99% of bike roller bearing sets are not sealed they are shielded. Even the ones with the rubber coated metal cover and all are still likely only a shield bearing. A fully sealed bearing has much higher friction loss than a shield or open bearing. We wimpy meat motors can feel even the seal friction……..

Some bearings are better than others at resisting intrusion and some lubricants are better at displacing water and also less prone to becoming a whipped frothy paste of water and badly reduced in value lube. My rain bike has BB30 bearings that would die at a rate of one good soaking and done. The bearings I get are cheap-o $7 a set types which I flush and pack with good synthetic HVAC bearing grease. This extends the lifespan to a year or so.

[huskerdont]

I changed my Shimano Hollowtech out because of a noise, but it turned out it wasn’t responsible for the noise. It cost like $20 or something though and I got to learn how to do it, so no harm no foul. Before I did much work on bikes, a Gary Fisher mountain bike’s BB once ground to a halt. My 1965 Schwinn had never been serviced and had bearings that looked like black gravel–brake cleaner and grease fixed that one up. That’s all I’ve ever done with BBs. Perhaps (as with the discussion of hubs a few months back where I also was doing nothing) I am doing it wrong?

[hozn]

@TwoWheelsDC 161554 wrote:

Because of course…

Yeah, the SRAM GXP spindle is stepped down from 24mm to 22mm (Shimano is straight 24mm). So the stepped-down part of spindle presses against a metal sleeve on the inside of the NDS bearing. I guess the advantage is that you can torque that NDS crankarm down as tight as you want into the spindle (and you do have to torque it to 40-50Nm to avoid it coming loose) and you don’t need to worry about squeezing your bearings. — Wheras with Shimiano you only carefully preload the left crankarm against the BB with the little plastic socket tool and then you tighten the pinch bolts to hold it onto the spindle. That probably won’t make sense w/o pictures.

[TwoWheelsDC]

@hozn 161558 wrote:

Yeah, the SRAM GXP spindle is stepped down from 24mm to 22mm (Shimano is straight 24mm). So the stepped-down part of spindle presses against a metal sleeve on the inside of the NDS bearing. I guess the advantage is that you can torque that NDS crankarm down as tight as you want into the spindle (and you do have to torque it to 40-50Nm to avoid it coming loose) and you don’t need to worry about squeezing your bearings. — Wheras with Shimiano you only carefully preload the left crankarm against the BB with the little plastic socket tool and then you tighten the pinch bolts to hold it onto the spindle. That probably won’t make sense w/o pictures.

When I replaced the BB on my gravel bike, I ordered the SRAM BB, knowing full well that the NDS was the smaller hole. Didn’t stop me from accidentally reversing them before I pressed everything in. I considered it a practice run…

[EasyRider]

@Vicegrip 161555 wrote:

99% of bike roller bearing sets are not sealed they are shielded. Even the ones with the rubber coated metal cover and all are still likely only a shield bearing. A fully sealed bearing has much higher friction loss than a shield or open bearing. We wimpy meat motors can feel even the seal friction……..

Some bearings are better than others at resisting intrusion and some lubricants are better at displacing water and also less prone to becoming a whipped frothy paste of water and badly reduced in value lube. My rain bike has BB30 bearings that would die at a rate of one good soaking and done. The bearings I get are cheap-o $7 a set types which I flush and pack with good synthetic HVAC bearing grease. This extends the lifespan to a year or so.

The SKF square taper BBs that Compass sells aren’t cheap, but they come with a 10 year warranty.

https://janheine.wordpress.com/2014/09/11/skf-bottom-brackets-after-5-years/

Of course, very few people want a square taper bottom bracket anymore, and fewer will pay $150 for a component that is hidden inside the frame without visible branding or color choices!

[Harry Meatmotor]

@EasyRider 161563 wrote:

very few people want a square taper bottom bracket anymore

I thought we already covered this one?

[Boomer Cycles]

I just replaced the BB on my Trek Madone with a Sram Rival (hollow) crank for the 3rd time in 12.5K miles.

It has an unique BB ‘PF90’ which are press fitted into the frame. The non-drive side bearing is prone to early failure, probably due to the magnifying effect of vibration from the crank side along a very long 90mm drive shaft. This eventually wears out the cup into which the bearing is seated inside the frame, to the point where you can pull out the bearing with your fingers (non drive side). There are lots of complaints on web fora from 2010-14 Madone owners, but Trek won’t warranty it. Instead they offer a “hack” with a special order PF9Ov2 bearing for the non-drive side. The v2 has an extra thick wall, 0.10mm thicker than the originally spec’ed bearing. It works, for awhile, until it, too wears out. Then you can shim (beer can metal is about the right thickness) or junk your carbon frame Madone. Rumor has it that if you complain loud enough, Trek will give you a few $100 credit towards the purchase of a new frame.

My experience is that the press fit bearings are very susceptible to water damage. The seals are flimsy at best. I should’ve pulled the bearings for servicing and replaced the seals every wet season. Better yet, I should not have ridden the Madone through 2 freezing saddle seasons (and only taken it out when the sun was shining). I’m now a fan of outboard bearings, which are easier to inspect, service and replace. More about that on my next post about blowing out a MegaXO BB!

Sent from my VS501 using Tapatalk

[hozn]

I honestly don’t understand why the industry is still churning out press-fit bottom brackets. I have never heard anyone say that they would rather have BB30/PF30/BB86-92 instead of external cups threaded.

[TwoWheelsDC]

@hozn 161690 wrote:

I honestly don’t understand why the industry is still churning out press-fit bottom brackets. I have never heard anyone say that they would rather have BB30/PF30/BB86-92 instead of external cups threaded.

One theory I heard is that press fit BB shells are way cheaper and easier to manufacture than threaded shells on carbon bikes. I can sort of see how that makes sense, assuming that manufacturers carried the PF BB style over to alloy frames for easier interchangeability among product lines (e.g. CAAD to Supersix). Given that most cheap steel bikes use threaded BBs, though, I can’t imagine that it’s a significant added cost for steel or alloy frames.

[n18]

If anyone wants a sealed bearing square tapper bottom bracket, here is one that costs around $14 plus shipping, and some sellers offer free shipping. They come in several sizes, like 68×115. The first number is the bottom bracket diameter, or shell width, which is mostly 68 mm, but some use the oversized 73 mm. Turn your bike over and try to measure the bottom bracket diameter.

The second number is the overall length of the bottom bracket in mm, which varies from bike to bike. It’s almost that you need to remove the cranks by a crank puller to measure its size. You also need this tool to mount it to the frame.

Not all bikes use square tapper bottom brackets. Some newer ones don’t even require crank pullers, they require either common or special tools. See “Shell width” column here to see which one you have. See also this video about the various types of cranks and bottom brackets

[TwoWheelsDC]

@hozn 161690 wrote:

I honestly don’t understand why the industry is still churning out press-fit bottom brackets. I have never heard anyone say that they would rather have BB30/PF30/BB86-92 instead of external cups threaded.

Interesting discussion on this topic…

http://road.cc/content/feature/223884-pressfit-dead-roadcc-investigates-and-speaks-specialized-and-bowman-cycles

As a side note, my new gravel bike (will be delivered on Wednesday!) has a threaded BB and I am very excited about it. SRAM 1x with a regular ol’ threaded GXP BB, just as the bike gods intended.

[hozn]

@TwoWheelsDC 161919 wrote:

Interesting discussion on this topic…

http://road.cc/content/feature/223884-pressfit-dead-roadcc-investigates-and-speaks-specialized-and-bowman-cycles

As a side note, my new gravel bike (will be delivered on Wednesday!) has a threaded BB and I am very excited about it. SRAM 1x with a regular ol’ threaded GXP BB, just as the bike gods intended.

Good read, thanks for posting.

But what is this new bike ?!?

[Author]

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