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Old 10-01-17, 09:41 AM   #26
CHenry
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Here is the BBC (UK) article on the recall.

Brompton recalls folding bikes over faulty bracket axle - BBC News

Seems like a fatigue issue - something I am rather an expert at! Fatigue Expert Services
Forged part, or sintermetal? I wonder.
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Old 10-01-17, 09:45 AM   #27
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..

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Old 10-01-17, 10:05 AM   #28
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Forged part, or sintermetal? I wonder.
Our technical team has said they expect it was a machining issue so forged and then machined the failure in the picture is fatigue from the bore to the outside, followed by overload (ductile) failure of the remaining section.

Machining can leave small steps in the metal surface which are stress concentrations that can then, as is likely in this case, cause a crack to start and, when it is long enough, the strength of the component will then be exceeded by the loads causing fracture.

I have personally had a problem with bending pedal axles in my early years riding up two hills every day. They did not fail completely fortunately as I could easily have had a bad outcome on my legs if they did.
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Old 10-01-17, 06:23 PM   #29
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I looked at the Shimano BB. The casing is steel but one end is aluminium. Wouldn't that be potential for galvanic corrosion (alum/steel bike frame, alum/steel BB housing)? Solution ... grease? Also with respect to the plastic housings, wouldn't the plastic housing be like only a spacer as the shaft is steel and the bearing "casing" is also steel. As long as there is no play on the shaft, then it should be good. Being plastic, there is no corrosion issues at all for BB housing.
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Old 10-01-17, 07:08 PM   #30
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I looked at the Shimano BB. The casing is steel but one end is aluminium. Wouldn't that be potential for galvanic corrosion (alum/steel bike frame, alum/steel BB housing)? Solution ... grease? Also with respect to the plastic housings, wouldn't the plastic housing be like only a spacer as the shaft is steel and the bearing "casing" is also steel. As long as there is no play on the shaft, then it should be good. Being plastic, there is no corrosion issues at all for BB housing.
Grease either way. Aluminum alloy seatposts in steel frames don't seem to be corroding away at significant rates.
And I haven't seen where alloy housings or the mounting rings are corroding badly either (or at least it isn't being seen as a big problem.)

The reason for plastic in the F.A.G. is likely neither corrosion-resistance nor weight-saving but cost-savings, using inexpensive nylon and inexpensive molding processes instead of more expensive metal forming and machining.
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Old 10-03-17, 12:15 PM   #31
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I looked at the Shimano BB. The casing is steel but one end is aluminium. Wouldn't that be potential for galvanic corrosion (alum/steel bike frame, alum/steel BB housing)? Solution ... grease? Also with respect to the plastic housings, wouldn't the plastic housing be like only a spacer as the shaft is steel and the bearing "casing" is also steel. As long as there is no play on the shaft, then it should be good. Being plastic, there is no corrosion issues at all for BB housing.
the lower priced Shimano UN .. BB uses a Plastic support sleeve, to not be subject to corrosion ,
but many people think this is a problem to solve with the aluminum one..


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Old 10-07-17, 09:03 AM   #32
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the lower priced Shimano UN .. BB uses a Plastic support sleeve, to not be subject to corrosion ,
but many people think this is a problem to solve with the aluminum one..


I doubt corrosion is a significant issue. I suspect their motive is costs reduction. If you check their catalog, Shimano is producing only one model of square-taper cartridge bottom bracket, with a plastic cup on the non-drive side. It has been many years since Shimano produced a crankset requiring a square taper bottom bracket (now only 2-piece with outboard bearings, prior to that, Octalink 3-piece, before that, square-taper) and most demand now for this kind of replacement component is divided between replacement parts for older bikes and higher end new "vintage" builds. High end vintage builders have plenty of non-Shimano options from Phil Wood and others, and are less cost-sensitive than OEM mass-production builders.

Look where 9-speed systems have been relegated--to the very lowest component lines. I would be surprised to see them available at all after a couple more years.
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Old 10-07-17, 09:11 AM   #33
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I doubt corrosion is a significant issue
Just read back thru the abundant ' I got a bike off eBay and the seat post is frozen', threads..
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Old 10-07-17, 09:36 AM   #34
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Had mine replaced today. Nearly turned out rubbish day because when I called about progress they hadn't even received the replacements in and were expecting them Monday (and I need the bike Mond - Fri). Went to collect it without the new bracket replaced and just as I was about to leave a delivery guy appeared with a box. Inside the first batch were. Mine wasn't one of them but luckily one of the guys working there let me have his, and he'll take mine when it arrives in the next batch. Ended up getting a discount on a torque wrench which I was looking at buying soon anyway .
Obviously no noticeable change, just the black plastic on both sides looks a little different.
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Old 10-07-17, 11:27 AM   #35
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Just read back thru the abundant ' I got a bike off eBay and the seat post is frozen', threads..
I get that, salvage bikes can have corrosion problems, but for bikes that are not neglected, that are cleaned when dirty, that are maintained and stored dry and out of the weather, frozen seatposts aren't really a problem.

Companies like Phil Wood don't seem to be rushing to replace their metal bottom bracket cup designs with plastic. If their buyers, paying $140 and up for a bottom bracket without the cups wanted non-metallic cups because of fear of corrosion, I suspect that would at least be an option (titanium is apparently available, for weight savings.)

When fewer steps to a finished product are needed, with cheaper materials and technology and less skilled work is needed, and the product has a reduced demand mainly as a replacement part for older bicycles, it makes sense to choose a simple, single design, use molded plastic where possible to save costs and be done with it. If the plastic resists corrosion better than the machined aluminum, all the better.
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Old 10-07-17, 11:39 AM   #36
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Phil has Stainless steel mounting rings , they recommend loc tite, a thread lock that also forms a layer between the 2 threaded parts..
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Old 10-07-17, 05:06 PM   #37
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I asked the Brompton dealer in NYC if I can ship the bb back and send a new one to me, they said that's not allowed. 6 of my Brompton bikes were manufactured between 2014~2017. That's not good.
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Old 10-07-17, 07:59 PM   #38
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I get that, salvage bikes can have corrosion problems, but for bikes that are not neglected, that are cleaned when dirty, that are maintained and stored dry and out of the weather, frozen seatposts aren't really a problem.

Companies like Phil Wood don't seem to be rushing to replace their metal bottom bracket cup designs with plastic. If their buyers, paying $140 and up for a bottom bracket without the cups wanted non-metallic cups because of fear of corrosion, I suspect that would at least be an option (titanium is apparently available, for weight savings.)

When fewer steps to a finished product are needed, with cheaper materials and technology and less skilled work is needed, and the product has a reduced demand mainly as a replacement part for older bicycles, it makes sense to choose a simple, single design, use molded plastic where possible to save costs and be done with it. If the plastic resists corrosion better than the machined aluminum, all the better.
I can understand why you won't see much galvanic corrosion for foldies with alum seat post. You probably move it up and down every time you fold. But for bottom brackets, I don't think you remove them every month to clean.

The Phil Wood's is like 5 times a plastic bb. What do you gain by paying so much more? Is it smoother? Better safety?

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Old 10-07-17, 08:46 PM   #39
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Phil has Stainless steel mounting rings , they recommend loc tite, a thread lock that also forms a layer between the 2 threaded parts..
Maybe the loctite is the reason you need the steel mounting ring.

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I asked the Brompton dealer in NYC if I can ship the bb back and send a new one to me, they said that's not allowed. 6 of my Brompton bikes were manufactured between 2014~2017. That's not good.
There are no Brompton dealers where you're at? Can't they just ship the BB only. Perhaps with a waiver form . Why do you have so many Bromptons by the way?
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Old 10-07-17, 11:18 PM   #40
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.....
The Phil Wood's is like 5 times a plastic bb. What do you gain by paying so much more? Is it smoother? Better safety?

https://m.youtube.com/watch?v=EDThYJ1OBQk
I replaced my BB with a PW after I had nothing but hell in outback Australia with my BB in July 2006. Had to get the locking ring spot welded to the frame to keep it from unscrewing.

The PW system has lasted since 2006 and I have never had any issue with it. Worth every cent I paid for it. MY 48 spoke front and rear PW hubs are the basis or really STRONG wheels on my expedition grade bicycle.

For me, spending the extra has (possibly) prevented trouble in the outback where it is maybe 1000 km to the nearest LBS. YMMV
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Old 10-07-17, 11:26 PM   #41
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.....There are no Brompton dealers where you're at? Can't they just ship the BB only. ...
Brompton has a strange policy in that they prohibit any dealer from shipping parts out of country into another "territory". Been there, done that. They will not even ship a rear derailleur from their UK parts store to me - and I am currently in a country with NO Brompton dealer.

Go figure.

As for Loctite - it is commonly used in industry to keep parts from unscrewing. Read up on it (from their website) and you will have your questions about it answered. I have used the red, blue and the green for different applications in my past career...
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Old 10-07-17, 11:47 PM   #42
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Yes I am familiar with Locktite. I have blue and red Loctite in my tool box. What I'm saying is that applying Loctite makes it harder to remove. You need more torque or you need to apply heat in order to remove. Perhaps that is why steel is required, coz plastic could break. See the circular reasoning?

Then to reinstall the Loctite parts again, you need to clean up the gunk between the threads.

What wears out is mainly the bearings. I don't think the housing moves much. Like I said, the plastic/or steel housing is more like a spacer (see the video I posted). Maybe the Phil Wood's bearings are better QC'ed, but at the end of the day, they are still ball bearings.
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Old 10-08-17, 05:49 AM   #43
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I can understand why you won't see much galvanic corrosion for foldies with alum seat post. You probably move it up and down every time you fold. But for bottom brackets, I don't think you remove them every month to clean.

The Phil Wood's is like 5 times a plastic bb. What do you gain by paying so much more? Is it smoother? Better safety?

https://m.youtube.com/watch?v=EDThYJ1OBQk
PW bottom brackets are benchmark quality, but that explains only part of their pricing. They choose a premium niche in the market. They build brackets compatible with nearly every brand made, both current and discontinued designs.

Phil Wood carries a large range of spindle lengths in both steel and titanium and manufactures locking rings in all of the common and obscure threadings. Their locking rings can be mixed for unusual requirements (e.g. damaged English shell threadings on vintage bikes being re-threaded to Italian threading on one side only.)

It's faster and cheaper to produce a precision part in plastic and that works fine for inexpensive parts like the Shimano and F.A.G. (and other low-cost) cartridge bottom brackets.

I doubt PW bearings are five times smoother. But they set the benchmark for quality and durability.

The Brompton posts are isolated from the frame tube by a plastic sleeve.

Last edited by CHenry; 10-08-17 at 05:53 AM.
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Old 10-08-17, 10:52 AM   #44
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I just use 2 mounting spline tools with my Phil BB's..
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