[Closed] Frame Alignment Specialist

Would you not be better talking to the manufacturer and send it back to them?

Pressfit or threaded?

For the former, a company with a CMM would be able to do that fairly easily. No more than a couple of hours to set it up and check each side for size and then for concentricity.

Hambini?

its for a threaded BB - so i'm assuming would need to thread BB type cups in for the measurement datum

The manufacturer is not being a helpful as i would like on the issue, hence why i'm trying to get a accurate set of measurements to use in my warranty claim

Good call - will contact 🙂

Messaged you via Facebook mate

An old tapered or ISIS bottom bracket is a good way to check basic alignment before involving any experts, it'll be obvious if it's out when you screw in the driveside, a hollow axle one let's you put a long rod through too, so you can check if the bb shell is 90° to the seattube.

I think that i have bottom bracket alignment issues on a new frame, so want a report to share with the manufacturer.

If it's a new frame, why not just send it back and ask for a refund?

Look at Paul Brodie's framebuilding videos on YouTube - he made up some pretty simple tools to check alignment.

Which parts are out of alignment relative to the BB? Chainstays, seat tube, downtube, headtube or all of them?

@greeny30 thats a good shout.

In theory pressfit should be superior, except its the bike industry where good design, manufacture and QC doesn't exist for the most part.

Which parts are out of alignment relative to the BB? Chainstays, seat tube, downtube, headtube or all of them?

I think he means from one side of the bottom bracket to the other?

The manufacturer is not being a helpful as i would like on the issue, hence why i’m trying to get a accurate set of measurements to use in my warranty claim

Name and shame, come on, I'll go get the bombers and the biscuits.

If your not happy with a new frame, return it and buy something else.

In theory pressfit should be superior, except its the bike industry where good design, manufacture and QC doesn’t exist people don't want to pay what a lot of items would cost if they were made to the standards needed, for the most part.

..ie blame those who thought these standards were a good idea at the design stage. If you truly believe that good design, manufacture and QC doesn’t exist in bikes - I really hope you're not riding carbon stuff.

In theory press fit was always a stupid idea for anything home/shop serviceable. I get that a square taper or HT2 is also a press fit in part but it's pressed with a lot more force, and probably more accuracy, in a factory.

Speaking from experience, if there's anything wrong with the frame, claim for a refund as soon as possible. Don't give them the benefit of the doubt, and don't waste your time getting them to sort it, especially if they're not being helpful at this stage. Also, if you've paid by credit card, contact them to sort it out on your behalf.

Now that Brant and Jameso have replied...

Is it on-one or evans 😄

What makes you think it's out?

Sounds like Mfr has not accepted how you have worked this out?

Hi guys - thanks for the great responses & ideas

Not gonna name & shame as i want to give them the chance to resolve the issue first, but also keen to know if there are people out there who can perform such a inspection.

Its a threaded bottom bracket and i believe that the opposing threads are out of alignment

Have you fitted any pedals and measured to the chainstay either side? Or is it assymetric stays?

boltonjon
Full Member
Hi guys – thanks for the great responses & ideas

Not gonna name & shame as i want to give them the chance to resolve the issue first, but also keen to know if there are people out there who can perform such a inspection.

Its a threaded bottom bracket and i believe that the opposing threads are out of alignment

Won't it take a BB op?

A few details about the issue will help matey, you don't need to mention the manufacturer.

Do you just mean the bb faces aren’t at the same angle?

I think he's saying the two bb shells aren't parallel, they are wonky, on the piss.

A threaded bb will work fine when new as they as seperate and threaded from either side with a plastic spacer inbetween.

Once you put the cranks in they will force the bearings out of alignment and have a poor spin. They will not be very efficient and the bearings will have a short life span.

Is the bb a one piece construction or bonded in at each side?

It's all a bit cryptic innit?

There's something amiss with the BB thread alignment, but a general lack of specifics...

What's led you to this conclusion OP?

If this is all as a result of that socially inept YT tosspot, I'm going to chuckle my little socks off.

What frame material?

Hey guys - sorry for being elusive

The pre-load on my crankset continuously backs off after 30 - 40 miles

To identify where the issue stems from, i have systematically swapped out components whilst searching for the problem part.

1) I started with a Sram crankset / Hope BB (with Hope shims)
2) then a Sram crank set / Sram BB
3) Then a Used Hope Crank / Hope BB (nearly new)
4) Finally, a new Hope crank set / brand new Hope BB

Parts have been installed by a professional and more recently, myself. Also, the BB threads have been chased by a professional

Even with the latest components fitted, the pre-load still backs off. The same fault as first experienced on the initial build with Sram Cranks on the Hope BB

The manufacturer doesn't agree, hence why i want to obtain an engineering report. If the threads are fully aligned, then i need to suck it up and continue my search for the faulty component, but if the threads are out of alignment, then i've found my problem.

Also, the BB threads have been chased by a professional

Assuming the professional used professional tooling to chase the threads, any significant mis-alignment would have shown up then. Decent BB thread chasing tools are in 2 parts, designed specifically to make sure the threads are in fact aligned.

Hmmm, my first thought on reading the list of (presumably none of them cheap) cranks you've tried isn't thread misalignment, but crank choice...

Most of them use an over complicated preloading collar system don't they?
SRAM and Hope cranks have (admittedly anecdotal) reports of people encountering issues with the preloading (amongst other things)...

I suppose there are a couple of easy home inspections/tests that you can do. First of all are the cups butting up cleanly to the BB shell on both sides? Any indication of a gap? That only tells you if the thread is perpendicular to the end of the shell, and if you've had it faced that sort of negates the test but it is worth double checking. Secondly do you have an old square taper cartridge BB knocking about? If so try winding the whole unit in (drive side) and then taking a look from the non-drive side (don't fit the NDS cup) to see if the assembly is obviously off to one side of another, possibly indicating some sort of miss-alignment. Do check the BB isn't just slopping about, the old un52 and similar were quite rigid assemblies, but play could develop.

If nothing immediately leaps out, rather than pay for an engineer to write an inspection report, I'd be tempted to try some shimano HT2 cranks next, no need to go bonkers and fit XTR, Deore or SLX work as well for this purpose and preloading is done in a much simpler way, finger tight on the end cap to take out play before you do up the pinch bolts and it should spin freely. If that works loose or seems a bit draggy then it probably does indicate an issue and you can flog the cranks again to part fund your Hambini investigations...

If this is a threaded frame then the stam bb you are using must be dub as gxp doesn’t have a collar and bb30 has bearings pressed into the frame. No reason that pre-load collar should unwind as it has an Allen key to tighten it down. I don’t see how this is an over complicated preload method. Yes Shimano ht2 is straight forward but given the various combinations of crank / bb here I don’t see all of those combinations have faults.

It seems like there must be something going on with the frame unless things aren’t being fitted correctly.

I don’t know how you’d go about measuring the trueness of the cups / bb faces / threads though - unless you approach a custom frame builder and see if they can check them for you for a small fee. Maybe the likes of Cotic / Curtis / Argos / BTR etc might help you out?

Try it with a UNxx Shimano bb like cookeaa said to at least check the concentricity of one side.

Try your problem cranks etc in another bike and see if they work OK (that proves the cranks and fitting technique).

Try finding a really old but decent quality cup and cone bb (bike shop should have a dusty old one you can borrow). Any misalignment might be more visually obvious and manifest itself as an inability to adjust properly. I had a frame replaced (1991!) where they had a big splat of brass in the nds threads. It had been tapped through but still stood proud, causing excess material to be removed from the opposite side. When you tightened the lock ring, it made the cup to skew on the loose threads.

With HT2, pushing the axle through and seeing how it aligns with the other cup will tell you.

Aren't these crank set ups similar...and that should work with them also?

Order a @hambini bb and get your lbs to install it. When they have issues send it to hambini for him to check it and roast it and put it in the C scale.

Because his bb are one peice any misalignment will show its self on the other side when the gap isn't uniform.

Cheers guys - some really good suggestions and ideas

The bike is a fatbike with a 100mm shell, so i am limited on options. I only wish Shimano would do a fatbike crank!!!

The Used Hope Crankset was previously installed for 4 years on a different fatbike frame and never once backed the pre-load off

Really like the idea of the UN51 sealed BB idea. I pretty cheap way to measure it

So we know it's a new fat bike with a 100mm threaded bb. Let's play guess the frame.

First impressions I thought canyon but they are all press fit.