Arc welding a bicycle frame

[malcolm]

Hey George, your threads are always fun.

Good choice not to weld that stem - I wouldn't do that even if I had the most expensive Lorch on the planet and was really good at welding.

There have been some great comments on this thread, and even if you want to chose your own path those comments ought to still be useful to others. They are based on failure modes. The analysis doesn't often come up on this forum but it seems to be influencing the recommendations in this thread.

Failure mode and effect analysis is a great subject to bring up. We've seen doubtful sill repairs on the forum in the past but what's actually going to happen if your sill falls off? Handling might get a bit soggy and you'll likely fail the next MOT but there's still plenty of car to keep the front wheels away from the back ones.

For cycle forks if the weld fails you WILL crash. How bad the crash is will depend on how fast you are going, though fast would be more load so that's when it will happen. That's why folk have been edgy in this thread. Failure mode (effect) analysis (FMEA) is all about balancing the chance of failure against the effect of failure.

If potential failure might be severe it's worth taking precautions to stop the failure from happening (like not welding it yourself if you don't know what you are doing and won't take advice from others). If the failure is unlikely to be severe less effort goes into trying to prevent it. The engineers on here will have been trained in FMEA. Everyone else who has commented has common sense - FMEA is the same thing just formalised.

Don't know why I wrote all that. What I wanted to say is I don't expect glue will work for the stem - pain in the **** gluing metal and that's why the gear knob on my Renault spins around. If you can get the handlebars working with glue let me know how it is done - gear knob ought to be easier.

 

[Drains]

Don't know why I wrote all that.

Excellent stuff Malcolm. And i think you said, in far less argumentative terms, what I and others have said already.

However, George, I understand exactly what you mean re unhelpful bicycle shops. I have a mountainbike, under ten years old, really nice light ally frame, needs a new bottom bracket. Our local cycle shop refused to fix it (said they couldn't), as it was too old. What nonsense. Mere fitters, obviously, who've never read Zen and the Art of Motorcycle Maintenance (which is a great book until it starts getting weird towards the end, well too weird for me, anyway).

I'll get round to doing it myself sometime. In the meantime, i'll make strange clicky noises as I tear down Leith Walk.

 

[BChild]

Don't know why I wrote all that. What I wanted to say is I don't expect glue will work for the stem - pain in the **** gluing metal and that's why the gear knob on my Renault spins around. If you can get the handlebars working with glue let me know how it is done - gear knob ought to be easier.

I used no more nails to glue a drilled pool ball to a gearshift - still attached after about a year

 

[Drains]

I used no more nails to glue a drilled pool ball to a gearshift - still attached after about a year

I challenge you to do the same with the steering wheel to the column!

 

[snowcat]

I challenge you to do the same with the steering wheel to the column!

Could we have a FMEA of the actions of that please!.....

Top thread BTW chaps, best in ages kept me chuckling right from the moment the Araldite was mixed together....

 

[mike os]

I challenge you to do the same with the steering wheel to the column!

what? glue it to the gearshift with no more nails?

 

[hotrodder]

i'll make strange clicky noises as I tear down Leith Walk.

Obviously if there's play in the bearings/they're rough it'll need a replacement but knackered bearings aren't the most common source of clicks/creaks when pedalling under load. Quite often stripping, cleaning and reassembling will cure clicking/creaking as it's often down to movement between the parts- favorite is the crank to bottom bracket interface, especially if a square taper type (a little locktite studlock on the tapers works better than fitting dry), although bottom bracket to frame fit can also cause it if the frame wasn't faced properly as can pedals but that tends to be confined to cheap parts with sloppy threads.

 

[Drains]

but that tends to be confined to cheap parts with sloppy threads.

Don't talk about my missus like that!
Rude man.

Actually H/R, you might be right. I have an inkling that it's the bearings in one of the pedals, not the bottom bracket. We shall see.



Sorry George, another off-topicker... No welding needed on my bike... yet.

 

[GeorgeB]

The next stage of my frame rebuild is to make some provision for supporting the brake and gear cables. I don't know how the cables were supported on the frame I'm rebuilding but there are no lugs, as on the frame I'm taking apart.

The first photo shows the lugs (maybe not the correct term) on the crossbar of the old frame. I've cut these out and propose 'grafting' them on to the new frame with a single (arc) plug weld in the centre. It seems simple and I'm hoping you won't suggest the crossbar might snap as a result of the heat from one or two plug welds.

 

[Tino]

It wouldn't be the part of the bike I would be worried about. Looks like a nice simple fix.

 

[chunkolini]

Or maybe a smalll spot weld on each corner.

Chunko'.

 

[GeorgeB]

Or maybe a smalll spot weld on each corner.
.

I could do, but I don't think it would look as neat. I'm confident that one plug weld will provide ten times more strength than needed as there's less chance of burning back the plate. I wonder how they fit those lugs in the factory.

 

[Wozzaaah]

I'd imagine they're brazed in.

 

[Alfaman]

George,

How did you get on with using glassfibre & resin on the bars?

Pics, please!

 

[GeorgeB]

How did you get on with using glassfibre & resin on the bars?
Pics, please!

Pictures to follow, for sure, once it's done. I'm pausing for thought, perhaps for good reason after all the warnings. I think Malcolm lives near Bedford. That's just about within range of a ride on this bike, once it's complete. I could always cycle over, say hello and submit the bike for some kind of risk assessment.

 

[Wozzaaah]

But what if it fails the risk assessment and Malcolm deems it unfit for road use?
You'd better make sure you bring some money for the bus ride home!

 

[Drains]

One thing to watch where you're welding those lugs in George - if you put too much heat into a weld on one side of the tube, the tube will bend towards it as the weld cools. I'd be more inclined to go for chunko's four little tacks, than one big plug.

 

[GeorgeB]

One thing to watch where you're welding those lugs in George - if you put too much heat into a weld on one side of the tube, the tube will bend towards it as the weld cools. I'd be more inclined to go for chunko's four little tacks, than one big plug.

Good point, but the problem is that I've already driiled a plug hole right through the centre of the small panel! Perhaps I can keep heat down by splitting the plug into quarters, like four micro plugs, building up to one larger plug. I would, of course, clear off all the slag along the way. Or I could 'plug weld' it with resin instead.

 

[Wozzaaah]

What about that double-sided carpet tape? That stuff sticks like the proverbial to the blanket!
Or a dab of 'no nails'?

 

[chunkolini]

George,
A speck of weld on each corner, then maybe blob of araldite in the hole to keep water out.
or of course, do we need braze ons for cable stops?

They are a pain the **** to fit and get right, maybe long lengths of cable outer from one end to the other of the cable run, with a few cable ties this also avoids water and cack getting into your cables and making life complicated. This was considered a cool option among mountain bikers a few years back, Until they discovered how to make cables that were cack proof.

XTR gear cables are the only bike tart components I have ever bought, wonderful things.

I can almost guarantee when you fit your cable guides you will fit them too close to the steerer head and end up woth horrible kinks etc. Unless you read this first. Also dont forget to slot the cable guides, see a mountain bike to get what I mean, it alloows you to dismantkle and lube your cables without taking the whole system to bits. An M6 nut spot welded to an M5 nut can make an acceptable cable guide.
No drinkig straws involved in cable guides unless it is yer brake cable................

chunko'. .