UnfilteredDregs

Anyhow...

I want to slap a nice, shiny & new compact on my bike. I'm not too fond of the Sugino I popped on it. Noodly, and the crank arm comes loose every 400-500 miles...That's a whole other story.

So....I did some research and settled on a crank, high quality, rather popular hardware, company with a very good reputation.

Before installing their crank on my bike (That I'm sourcing via my LBS) the manufacturer sends out a gauge to ensure my BB shell is in tolerance.

Quick rewind to last week. I get a call from the LBS, they have the guage (a machined disk that you insert into the shell) and I go down for a tuneup and to check to see if my BB shell is in tolerance, I had just assumed this would be a non-issue, that my shell is precision machined by a manufacturer with an excellent reputation.

Now ,what was funny and discovered in the process is, my old bottom bracket a Shimano BB91-41, the drive side bearings were TOAST, the non-drive side, smooth as buttah.

I have 4500 miles on the bike, and I thought that was quite weird. I understand that people get many more miles out of a good BB than this...besides the difference in wear between drive/non-drive sides is way out there. As I said, non-drive side is fine, drive side is grinding.

Anyhow, we pull the crank and the BB, take the guage and discover that the drive side of my BB86 shell is not concentric, the non drive side is... Now it's close but there's a visible gap between the guage and the shell, bad picture but you get the idea:



This is a titanium frame.

Considering the money I paid for this bike, well, I want a warranty frame replacement.

Any thoughts or relevant experiences with such matters would be greatly appreciated.

I'm not happy.

garysol1 

I have never heard of a crank manufacturer sending out a BB shell gauge....... but what do I know. Apparently you already have had a threaded BB in the bike so I cant see the shell being that out of round. My .02 is thread in a new BB, install the crank and ride your bike!

dr_lha

You missed the part where his BB is press-fit.

digibud

look at Praxis bottom brackets. Dunno if it's a solution but there's a good chance it would work. A new frame would be a better solution....

rpenmanparker 

BB shells are commonly less than perfect. I imagine moreso with press-fit ready shells than threaded ones. Maybe that is why so many folks report the need to replace BB bearings frequently. We certainly never had to do that with theeaded BBs in my experience. I would just liberally apply the green Loc-Tite and ride off into the sunset. Bearings are cheap. Replace them as needed.

garysol1 

My bad.... Carry on

UnfilteredDregs

Interesting that you say that, Praxis is the crank I'd like to install, they sent out the gauge to my lbs.

I get that can be a possibility, how common?

Nevertheless, specs are specs and warranties are warranties. If this was a cheap bike, I'd probably say the hell with it. But, not a cheap bike and I'm not too keen on the idea of absorbing additional maintenance costs for lopsided bearing wear, besides the occasional creaking (That I presumed was the crank's fault) that may or may not be associated. I have to question the overall QC...

Hiro11

Exhibit 61,406 why press fit sucks: if the tolerances are off just a little bit, everything goes wrong.

rpenmanparker 

Everything you say is true, but it is just a question of how much aggravation you can stand. It may well be that the shell is not out of spec. The tolerances may be pretty loose. But go for it if that suits your personality.

I had an aluminum Trek 1000 back when they were first introduced that had a sloppy, oversized BB shell. It required red Loc-Tite to tighten the threaded cup on that side. Maybe I should have sent it back, but I just lived with it, and everything worked fine. DSFDF

UnfilteredDregs

Yeah, it is what it is, I can ride the bike so aggravation is minimal at this point. You bring up a good point, what is their actual in-house spec? What exactly does BB86 mean in terms of what is acceptable conformance to the specification? I'd think at least being ROUND ought to be a minimum.

I've been speaking with a custom builder on another matter...... and he said, "Usually distortion happens from welding but is then corrected during post weld machining.."

rpenmanparker 

Yeah, I should say before we go any further that I wasn't being snarky about, "if that suits your personality." I realized after the fact that might have sounded a little pissy. I just meant that some folks could stand the aggravation of the imperfect bike better, and other could stand the aggravation of trying to get it replaced better. Sorry if it came across wrong.

Back on topic, I think round would be a minimum requirement, at least within a couple of thousandths of an inch. But who knows? I wonder when you press the bearings into that shell whether it deforms them (and perhaps the shell too) to make a seal all the way around touching the shell? Or can you still see daylight?

UnfilteredDregs

It's all good. As you know I'm argumentative by nature. This falls in the you should get what you pay for section, $4600.00 msrp. and I do have a 5 year warranty that covers manufacturer defects.

I'm going with the assumption that pressing the bearings into the shell will deform them due to the condition of the bearings within the original Shimano bottom bracket I removed. I slapped in a cheap BB in the meantime...

...and if my shell is specified as BB86 as per the manufacturer...why in the hell is it 92mm wide?!?!?!

rpenmanparker 

As to the last, BB86 is just a cutesy name. I have no idea what the target width of the shell is. It is just important that it fit the crank spindle.

justin1138

it's the mountain bike variant to bb86, 91.5mm wide. maybe this is partially why the sugino crank didn't work out so well?

Jiggle

I would just ram some $10 bearings in there, install the crank, and change them out 4500 miles in the future. Only takes like 20 minutes.

UnfilteredDregs

It feels slightly narrow, heels barely clear the stays, but the chainline is okay. The Sugino's non-drive side arm was loosening from the splines and the compression cap was loosening as well. Nothing to do with the width of the shell...

hueyhoolihan

it's possible that a crank designed with pinch bolts to secure the crank arms could be attached insecurely to a to spindle that is five and one-half millimeters too short for the true width. thst is, outside of bottom bracket bearing to outside bottom bracket bearing.

might not be a bad time to measure the BB shell width, the true bearing to bearing width (if different) yourself and double check the literature on the sugino crank for BB width specifications. if there are discrepancies found it may explain the slightly ovalized BB shell too, if it's the side where most of the power/weight comes from.

GuitarBob

We can only speculate. Send the photo and explanation to Salsa... what would they suggest?

I have little doubt that you could make it work, but I'd still toss it in their court first.

Stucky

I'd certainly want to pursue the warranty. BB shell being out of round on that one side is probably why the BB got toasted on that one side so young.

Curious: What brand of bike is this? (If you mentioned it, I missed it, as I read through the thread kinda fast...afraid I was going to see something about disc brakes )

They had to really screw-up bad to make an eccentric shell on a titanium bike...and it's likely something which affected many of their bikes- so hopefully, it's a known and acknowledged problem, and will therefore make the warranty claim easier.

gamby

I have zero interest in a press fit bike. I'll go custom when I'm unable to find something threaded (assuming threaded remains available).

pdedes

Is BB86 like BB30 in that the bearing spaces are milled to tolerance after the frame is complete?

UnfilteredDregs

I'm not going to slag anyone until I go through the warranty process. It is a brand known for a very good bike.

I bet I pulled my ti BB out of round because of the asymmetric forces applied to the frame with my massively overpowered disc brakes...lmao

BTW, Hi Stucky!

What makes you presume this? I'm not up on the manufacturing process.

UnfilteredDregs

thanks for pointing this out, and I did revisit the installation manual and correspondence with the manufacturer. I had received an all clear from them regarding using the existing Shimano BB, and in terms of how the crank comes together and seats via the compression cap it's all good. They think I may have initially damaged the splines (Nothing visible btw...) by riding the crank without the arm being torqued down sufficiently. I have the original paper installation doc, where it clearly states "7-9Nm"...they put out a technical bulletin 2 months later increasing the spec to 13-15nm and have since corrected their online documentation, although a typo still remains that says 7-9Nm meanwhile on the illustration the callout says 14-16Nm....Have a look, on the left 14-16Nm, in the box on the right, 7-9Nm:

JohnDThompson 

Welding often causes the shell to distort. With threaded shell, this is corrected when the shell is tapped. With press-fit, I imagine the manufacturer must ream the bore so it's round and the proper diameter.

UnfilteredDregs

This is consistent with what builders are telling me. Post weld machining is supposed to ensure the BB shell is true.