Thank you for another exceptionally interesting post. I had no idea there were so many incidents, let alone court cases. I've learned something. By mentioning the handlebars, you have me even more worried now! I removed aluminium handlebars from another bike but had to cut them off. I hope to try aluminium welding for the first time to put them back together on this new build. My expectation of being able to make an acceptable weld on that aluminium, is low, and the risk of a crash much higher, I think, than with the front forks or rear brakes.
- Thread starter GeorgeB
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Thank you for another exceptionally interesting post. I had no idea there were so many incidents, let alone court cases. I've learned something. By mentioning the handlebars, you have me even more worried now! I removed aluminium handlebars from another bike but had to cut them off. I hope to try aluminium welding for the first time to put them back together on this new build. My expectation of being able to make an acceptable weld on that aluminium, is low, and the risk of a crash much higher, I think, than with the front forks or rear brakes.
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George, I'd love to be sitting here with a mental picture of you sat there rubbing your hands thinking "and if they believe that then they'll believe any old tosh" but I fear you're actually serious!
What machine do you intend to weld the aluminium with?
To quote an old joke;
Look mum...no feet
look mum....no hands
look mum.....no teef!
I fear you're actually serious!
What machine do you intend to weld the aluminium with?
Of course I'm serious. If anyone lives near enough, I'll cycle round to see them when the bike is finished and they can confirm this is no wind-up.
Here are photos of the plate for the rear brake, and the handlebars.
BRAKE PLATE: finished. Could I get it silky smooth for a car body? Of course. Can I be bothered for this old bike? No.
HANDLEBARS: view looking down. Perhaps I really need to get a new stem, or whatever the L shaped bit is called. I damaged this old one, made of aluminium. I thought I could use an AC arc welder to blitz it with a bit of TIG welding, not that I've ever tried TIG welding. Or put some aluminium wire in the MIG and hit it with that. It will never look neat and tidy but could I ever make the joint strong enough? At present, the handlebars can rotate relative to the stem and damaged clamp.
The buzzbox is an AC power source so I thought it's worth a try. I hoped it might work, even if not very well. I'm told you can't use scratch start with aluminium but is it certain the arc will extinguish without HF support? I must try it on some scrap aluminium, to find out.
Drains
Yeah, nah.
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oilcooled :)
Pipe Welder, Mechanical engineer
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george, you could use aliminium welding rods for your arc welder, but it would be tricky work, with the low melting point of alu and its high heat conductivity, only a thought
Good idea! I'll see if I can find some rods. Any idea how many amps I'd need in order to somehow fuse together that area - stem and handlebar - everything - into one solid mass with MMA?
Alfaman
Banned
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If this is the same court case as the one I read about a couple of years ago, then apparently it came to light after the case was settled in the cyclist's favour, that the bike had been involved in a number of quite 'high-speed' incidents prior to the handlebar fracturing and throwing the guy down the road.
Given the loads that go through the bars (especially on mountain bikes) I replace the bars on my Giant XTC 3.5 annually. I do the same with the saddle post, as I'm 95Kgs and no lightweight. Too many pies and lager, I guess
It's entirely possible. My only knowledge of the case is from the lecture I was given. It was probably the most (read only) interesting bit of the lecture! As I recall they requested samples of the handlebars for testing at the uni. It probably got farmed out to some group of students as a project!
As I recall they requested samples of the handlebars for testing at the uni. It probably got farmed out to some group of students as a project! 
chunkolini
celebrity artiste
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George, the stem is one of the most dodgy bits of a bike to mess with, it has a large part of the weight of an adult thrashing about on it, that one is aluminium, hardly the place to start learning to weld aluminium, buy a bulk pack of straws.
Chunko'
Chunko'
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George, as for you own bike it's difficult to know what the results will be. For example, if you intend using the bike for pottering about on the road then it's unlikely to ever experience the peak loads that a heavily used mountain bike might. There are also considerations related to the grade of aluminium, the quality of manufacture, tube thickness, etc. etc. I would suspect that, in all likelihood, your modifications will be safe enough. If the bike is to be used at low speeds on the flat then you're unlikely to come to much harm even if the front wheel does fall off or a handlebar breaks. But you should be aware that metal fatigue results in sudden, catastrophic failure. You are unlikely to have warning unless you inspect regularly for evidence of cracks which, in many cases, won't be visible even if they are there.
Thank you for the offer. Mine is for a 'racing bike'. The vertical bit (horizontal in the image) goes into the frame and is about 22mm diameter. The handlebars are about 25mm. Everything is aluminium and I like that, to keep the weight down.
I had to cut it out of the original frame due to total seizure.
The cracked/cut part is the only bit I need to weld. For this, I'm thinking MIG with pure Argon may be best, rather than run the risk of slag with arc welding aluminium.
Chunko and Archie - your last posts were made while I was loading the photo. I agree the handlebars worry me more than the forks but the concept/likelihood of sudden failure of anything, without warning, also concerns me. Wouldn't one fork go, and the other side hold up for a few seconds? This bike is for road use but, in a sense, being next to traffic might be more risky than failure on a cross country track. The biggest normal impact will be riding off a kerb. If I ride off 10 kerbs as a test, it could still break later.
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I'd say a fraction of a second George, one goes, all the force then acts on the other one (and it is a lot of force) then that goes and the result is.......wheee (number of e's in wheee is directly proportional to velocity at the time of failure) .....smeck! (That's the sound of teeth on tarmac
).I'd say a fraction of a second George, one goes, all the force then acts on the other one (and it is a lot of force) then that goes and the result is.......wheee (number of e's in wheee is directly proportional to velocity at the time of failure) .....smeck! (That's the sound of teeth on tarmac
I'd say it's probably inversely proportional!
Yeah, yeah. I'll get my coat.
I just looked on the Miller web site for some idea of welding power needed for aluminium. I selected TIG, 0.25" butt (and it's probably a lot deeper). They said it needs at least 190A, even for 0.25". Wow! I know how powerful 180A feels for MMA and it's hard to believe it would take all that energy. Perhaps I should use epoxy resin and glue it together. Even if it breaks, the handlebars will just twist. They won't fall off.
