SesameCrunch

Just found this on my brand new Bridgestone Moulton.

Foldable Two

SC,

That doesn't look good! That's the seat tube, right?

Have you gained some weight lately???

Lou

lucille

I would say it's a very bad thing.... Can you exchange the frame?

SesameCrunch

It's actually the frame itself. Here's a picture that show the orientation of the cracked tube.



And, no, I haven't gained weight! Pfffft!

SesameCrunch

Trying to sort that out. This bike was purchased in Taiwan and brought back to California. There is no US dealer for Bridgestone.

Foldable Two

Thanks for the pic - can see I was 90 degrees "out-of-phase" as to where the crack is.

Large welds, so it's an aluminum frame?

Interesting problem - so maybe you should have sold it vs. the Bike Friday? Hindsight...lol

Will be interested in hearing what the solution ends up being.

Lou

wahoonc

Duct Tape? JB Weld?...

Honestly I don't know what to tell you, the last aluminum frame I had that cracked I stripped and sold off for the scrap value.

Aaron

ratdog

Now I feel bad that I voted to sell the BF to keep the BM.

kamtsa

After taking apart the steering column this is actually a relatively small part that is not too difficult to ship.

invisiblehand

Sorry to read this SC.

BruceMetras

I think the problem would be that an identical replacement piece will be susceptible to exactly the same type of failure .. the hope would be that there would be a structurally updated replacement frame member, and that, could be sent here .. even if SesameC were 20lbs less lumpy, I could see that frame having issues with a strong rider..

SesameCrunch

^^^^ What Bruce said....(except the part about me being lumpy )

Someone on the Moulton Yahoo Groups site said this is the third such instance he's heard of. Very disappointing from Bridgestone.

I am eager to hear if Bridgestone has a new, reinforced frame. Otherwise, I have no confidence that the replacement won't do the same thing.

The backup plan (thanks to Bruce) is to weld a sleeve over the the frame to strengthen it. Then paint over with pearl white. Otherwise, I would be queasy about taking it on long, aggressive rides.

SesameCrunch

Yeah, it's pretty ironic that both bikes are gone. Sold the Bike Friday, and the BSM went on strike. C'est la vie!

Foldable Two

Not being a Moulton owner myself, how does that joint stay together when bike is fully assembled? Pressure on inside walls of that cracked piece?

SesameCrunch

Exactly! So there is pre-loaded tension on the frame. Add one 190 lb rider with big thighs and voila! Crack on the underside of the tube.

Bacciagalupe

FWIW, I doubt the frame design needs to be revised. I may be wrong but I suspect they've used the same design and tubing specs for many years now.

I'd think it is much more likely to be a garden-variety manufacturing defect. As long as you have proof of purchase, you ought to be able to get it fixed under warranty somehow.

fietsbob

I See, its the front half of the break apart frame joint.
Probably don't want to send it back across the Pacific for dealer to exchange/ repair.

A skilled welder can repair that frame crack. you will need to spot touch up the paint afterwards.

I'd leave the bead of the repair built up on the surface...
perhaps have a doubling sleeve, a long gusset added, on the outside.

Berkeley Jitensha used to bring in the Japan made ones, call for recommended local repair people

Now you know why Sir Alex's bikes were steel framed.

SesameCrunch

Yes, totally agree with your diagnosis and plan to use a sleeve. I have a master welder lined up to do this work, and am just waiting to hear back from Bridgestone to see if they have a more fortified substitute frame.

I emailed the Jitensha person. He wasn't able to help much. Just referred me to a Japanese website.

SesameCrunch

The difference is that this separable frame is held together by an expansion joint (turn a bolt to tighten). So, there's pre-loaded tension already. Then when I sit on it, it creates more tension on the lower half of the tube.

I would be more inclined to think this was a garden variety crack if I hadn't heard that there were three other known cracks within the Moulton Yahoo Groups community.

Folder4life

That sucks it would happen to such a fine expensive bike.

Foldable Two

Sounds like you've done your homework. So now, maybe you can resume your regular life!!!

Bacciagalupe

Unless you're well over the weight limits, I still seriously doubt it's a major design issue. It's not like the expansion joint is putting 200 lbs of force on the bottom of the tube. And they've used this design since when, the 60s?

Of course, if it is a design flaw and there is a recall, I guess you'd only find out if you read Japanese, yes?


Three cracks out of how many owners, exactly? At any rate, it's hard to say if that is in any way statistically significant -- nor does it exclude the possibility that someone at the factory just isn't doing their job right, or that someone in QA was/is slacking. Even a recall wouldn't definitively indicate that it's a design flaw, since an undetected error in the manufacturing process could easily affect a large number of units.

I'd say though this is a pretty good reason to stick with a bike manufacturer that at least has a distributor in one's nation of residence, though....

SesameCrunch

I think most of the Moulton F-frames from the '60's were not separable, so there is no locking mechanism. Plus, they were steel.

SesameCrunch

Yeah, it's a good thing I have other bikes to ride

Dynocoaster 

Looking at the tubing is it possible to build a steel frame and transfer parts? Thinking out loud.