davei1980

I have a SRAM dub BB/crank combo. It squeaks a lot. With no small amount of fussing with the preload collar on the left side, I got it to stop when the bike was new (incremental turns back and forth until I it the perfect preload spot).

The cranks are now pretty banged up so I was thinking about just switching over to something like Zee or SLX and whatever threaded BB shell Shimano stuff is compatible with (Hollowtech II?) these days when my BB finally wears out.

Based on your experience, are the Shimano MTB BB's less headache than SRAM DUB? Should grease be introduced at all to quiet the squeaking or is this just a symptom mask? I know I am not the first to complain about squeaking. I am also not above warrantying out if it's actually defective. Some people told me to wear earplugs. I get it but I don't think that way. Stuff should just work.

Bob the Mech

Shimano XT MT800 treaded Bottom Bracket fitted to my hardtail MTB with the Shimano Zee M640 10sp MTB Chainset. Can't say I've had a problem with it. Shimano BB-R60 Ultegra treaded, fitted to the steel road bike, again no issures. I've used both in some pretty foul conditions and I've not been disappointed. Much prefer these to the press fit on the Trek which is a little more demanding in the maintenance department.

davei1980

Thanks. I am a big fan of Shimano stuff, in general, it's always a good value and works great. My question had more to do w/ SRAM vs. Shimano more than threaded vs. pressfit. My BB shell is threaded, 73 I think.

Bob the Mech

My bad I'm a Shimano fan boy at heart and have never used anything else, never had the need to. I'll just get my coat and leave by the back door...no need to show me out...

davei1980

Shimano fans always welcome on my posts! I would be running the stuff if my bike came with it!
FWIW I am seriously considering getting Saint pedals. They look rad and the options in that price range are so many, it's overwhelming.

They are like the Honda of components: affordable, work great, but not all that sexy

cpach

Before you give up on Dub, you may want to have your BB shell faced and chased. All external bearing bottom brackets are fairly sensitive to misalignment of the shell.

Worn bearings will make noise regardless of brand, so check those.

It is more difficult to get and maintain extreme tolerances for the bearing seats with a larger aluminum axle than steel, and Sram has been criticized for tolerances on their cranks, so you may have better luck with Shimano, but as a system design Dub is fine.

davei1980

Wow. That's super insightful. Thank you! Is the alignment (faced/chased) of my BB shell something my LBS can tackle? I am pretty handy but that sounds WAY beyond my skill.

I actually watched a vid on Hollowtech II and I now see how similar the two systems are: they both use a left side doo-hickey to add preload. I was thinking the goofy collar on my crank which does the same was the culprit.

And finally, how do I tell if bearings are worn?

cpach

Bearings are worn if, with the crank removed, you turn them by hand and they feel crunchy, or if they have play that you can't eliminate with preload.
Your LBS should be able to face and chase. If they aren't I scoff at them and declare them not a real bike shop. Basically the shell was threaded as one unit so it's probably reasonably aligned in that sense but sometimes the shell faces aren't perfectly parallel and that's basically what determines the bearing alignment. The most common culprit is paint overspray but it can also be part of the carbon layup or even the original steel shell. The tool taps the threads, and then stays in place to act as a guide for the facing tool. It's actually not especially hard to do but the tools are comically expensive so this is one I'd leave to a local shop or do at a co-op if I wasn't in the industry.

davei1980

The LBS I go to is a really high end shop with some good guys. I had just never heard of this! great suggestion!

EDIT - By "high end" I mean, they are the only BMC, OPEN, and Evil dealer in a very large radius of here. Those are thought of as pretty high end brands. They also carry the more bread and butter brands like Kona, Norco, and Rocky Mountain. They are in no way elitist and they are very down to earth. The owner rides a Rocky Mountain Solo as his daily rider.

smashndash

I’ll throw in my 2c. I don’t think there’s anything fundamentally wrong with the DUB design. It’s possible that the crank wasn’t produced properly or that the frame wasn’t produced properly. If it’s the frame, you’ll find out in short order - at the cost of a crank and BB.

I say go for it. It’s probably cheaper and easier than asking someone to precisely measure your frame and crankset.

davei1980

After I posted this I researched Hollowtech II a little more and realized they have a really similar doohickey for setting bearing preload; the two systems are more similar than I thought.

Missing the old sq tapered days right now!

smashndash

Nahh you can have problems with square taper too. My crappy fixie made a spine-tingling CRACK every time I jumped on the pedals. Bad engineering knows no bounds.

davei1980

I thoroughly cleaned everything in the drivetrain and took about 1/8 turn of preload out. Did a road ride this am and my drivetrain was SILENT.

So through this process of adjusting, getting it right, having it go out of adjustment, and considering replacing with another BB/Crank combo, I learned a few things:

1. I think all modern 2 pc cranks have some sort of preload collar or ring or bolt that can, from time to time, go out of adjustment when parts wear in
2. SRAM and shimano look very different but mechanically they're very similar (news to me)
3. I think I will stick with dub because: a) it's what I have and b) it actually looks easier to service than Hollowtech II with fewer specialty tools
4. I am still a great fan of Shimano; I am looking at an old bike with Tange Infinity tubing later which would be a great candidate for my Ultegra long cage DR sitting on the shelf

I guess the overall lesson is to learn about what you (I) have instead of jumping to replace with something that is actually or perceived to be better.

smashndash

Uh. This is definitely beyond my realm of knowledge, but I'm not sure that the difference between "works perfectly" and "makes a squeaking sound when pedaling" ought to be just 1/8 of a turn. It's a fairly fine pitch adjuster, right?

This makes me think that, when you had a bit more preload, the spindle was spinning/slipping inside the bearing and making a noise. Now that you've reduced the preload, perhaps it's still slipping, but there's not as much friction between the cranks and plastic reducers in the bearings - so you can't hear it anymore. What you can do is put some kind of pigment on the journals of the spindle (where the bearings touch) and ride the bike for a couple hundred miles. Then take out the crank and inspect it. If you're losing (a lot of) paint, then that is evidence of slippage.

This is caused either by misalignment of the BB (bad frame, very common) or an out of spec crank spindle (easy to measure with calipers).

Again, take this with a grain of salt.

davei1980

First of all, thank you, sincerely for the feedback. I am new to this style crank so I really do appreciate this theory, I honestly hadn't considered this. That said, 1/8 turn does make a huge difference on this preload collar, in my limited experience.

This reminds me of why I keep a nice collection of Sharpie felt-tip pens in my workshop! And thanks for explaining what a 'journal' is, it's not an intuitive word to understand. By sheer happenstance, I knew what you meant, I have dropped a few crankshafts off to the machine shop to have the rod journals chamfered. Now THERE's a word. LOL