Good metal worker in london?

[cwah]

Hello there,

I'm having hard time widening my brompton rear fork from 112mm to 135mm.

Does any of you know a good metal worker in London able to do that for less than £100?

I had a quote from a bike frame builder at 200-400+£ juste to widen the fork, it's way too much!
I also meet a metal worker telling me I had to replace the complete rear fork to one from another bike. (no way!)

Here is the motor I intend to fit:

Many of you live in London, any idea where I can find someone reliable for the task?

 

[Oxygen Bicycles]

Hi Cwah,

The task you are trying to do isn't easy. The rear forks have a high level of flexibility but once you try to to extend those they will work like a spring and will be returning to it's orginal position. In order to get the 135mm you would probably need to extend them to about 165-170mm and you have a chance of them returning somehwere close to 135mm. I assume these are cro-moly forks arent' they?

There is also another rish of the forks cracking somehwere. In case you need a good welder I can recommend you Aplha Welding in West Croydon (can't remember the street but it's one the London Road strrets. There is an old guy doing TIG welding for over 25 years and he's really good in it. Wish you luck, keep us posted,

all the best

Andrew

 

[NRG]

Have you tried to bend those already? If so you've put a kink in both legs and not in the same place! sorry cant help with a location but hope you get it sorted...

PS, either Jerry or Dan bent the front forks with a threaded bar inserted between the legs using the correct nuts on the inside to slowly force them apart...

 

[flecc]

PS, either Jerry or Dan bent the front forks with a threaded bar inserted between the legs using the correct nuts on the inside to slowly force them apart...

You may remember I did that on my Q-bike, but I did also deliberately part two welds as well to get enough shape, re-welding afterwards. Pics below show stages, first expansion, then further expansion with rear clamped to bring dropouts back to parallel, and the finished welded and polished job:

 

[neptune]

@Cwah . As I see it from the photograph , you have two problems . First , the frame needs to be widened quite a lot . and also the frame tubes appear to be curved . I understand a Brompton is not a cheap bike , so you probably do not wish to risk a write-off . If you are committed to this modification , you will have to repaint the frame afterwards . A crude way to do this is to force the frame apart with a car jack of the scissors type . Things to watch are , try to get both sides to bend the same amount . Also , watch that you do not crack welds .Failing that , look for a different frame that has the right measurements , or is cheap enough to risk major surgery .
Sorry , flecc beat me to the post .

 

[cwah]

Thanks Andrew for the address. Croydon is quite far from where I live. I'll have to post my bike there and that may be quite expensive. Is there some metal worker closer to central london?
I just know the frame is steel, I purchased it second hand (the bike is from 2006) so I don't know if it's cromoly or not.

NRJ, bending the front fork is way easier because there isn't a crossbar. I haven't really tried to bent it because I'm not sure if I'll do it correctly.

Flecc, you live in London, right? I have no skill in welding at all lol

 

[cwah]

Neptune, I had this brompton second hand for £270. I deliberately purchased the cheapest possible because I intend to do deep modification.

I was considering using a car jack but I probably need to remove/cut the crossbar first and weld it again later. Problem is that I don't have any welding skill.

 

[cwah]

Here the crossbar prevent me from bending the frame with a woodbar:

 

[flecc]

Flecc, you live in London, right? I have no skill in welding at all lol

Right on the bottom edge of South London, Surrey border, so same problem for you.

To be honest what I did on my bike was very risky and I wouldn't be inclined to risk it on someone elses. Mine was a 20" wheel bike which was a bit easier, but doing the same on the very short rear tubes of the 16" wheel Brompton is much more risky. Both the shaping and the welding of thinwall alloy tube are very tricky and entirely judgement based, and I'm far from being an expert welder, my end result needing a lot of tidying!

P.S. Looking at your photo just posted, it really will be a problem to get that widened enough and it's certainly beyond my skills and equipment.

 

[eddieo]

there looks like hardly any leverage there...why not front motor?

Croydon is about 20 mins on train from central London

 

[cwah]

Right on the bottom edge of South London, Surrey border, so same problem for you.

To be honest what I did on my bike was very risky and I wouldn't be inclined to risk it on someone elses. Mine was a 20" wheel bike which was a bit easier, but doing the same on the very short rear tubes of the 16" wheel Brompton is much more risky. Both the shaping and the welding of thinwall alloy tube are very tricky and entirely judgement based, and I'm far from being an expert welder, my end result needing a lot of tidying!

P.S. Looking at your photo just posted, it really will be a problem to get that widened enough and it's certainly beyond my skills and equipment.

Ok thanks Fleec. Will try to bother someone else with my problem lol.

 

[cwah]

there looks like hardly any leverage there...why not front motor?

Croydon is about 20 mins on train from central London

I prefer rear motor because I have more motor choice, I only need single speed gear (and that can make my bike lighter), it's more stealthy and I can do wheelies.

But if there is no other choice I'll probably get the Crystalyte G209.

 

[Scottyf]

The crossmember needs cutting. It won't bend outwards without it.

To be honest if I had this problem and really wanted the rear motor I'd really look at cutting the entire drop out off and fitting a complete thicker widened one instead of bending the frame.

As the bikes steel it should be fairly simple to get someone to do it.


However if you intending on bending the steel I'd opt for Flecc's demonstation using a car jack, cutting the cross member and then getting someone to re-weld a complete new piece.
It won't be pretty but would be functional.

Either way that short of movement will put alot of strain on the welds while you bend it.

 

[cwah]

The crossmember needs cutting. It won't bend outwards without it.

To be honest if I had this problem and really wanted the rear motor I'd really look at cutting the entire drop out off and fitting a complete thicker widened one instead of bending the frame.

As the bikes steel it should be fairly simple to get someone to do it.


However if you intending on bending the steel I'd opt for Flecc's demonstation using a car jack, cutting the cross member and then getting someone to re-weld a complete new piece.
It won't be pretty but would be functional.

Either way that short of movement will put alot of strain on the welds while you bend it.

That's what proposed the frame builder, to completely change the rear fork to something new. But he charges 400£+!!! That's more expensive than my bike!!

I live in London, it shouldn't be that hard to find someone able to do that here.

 

[flecc]

I agree with Scotty, but I doubt it will be possible to bend those large diameter short tubes enough without them crumpling, I certainly wouldn't risk it.

Either a new rear frame section as Scotty suggests, or part and reassemble the present tubes to the new format with rear dropout plates re-welded back into place parallel.

 

[cwah]

I agree with both of you, my problem is to find someone able to do that at a decent price

 

[johnc461165]

I wish you lived near Wigan I'm itching to get my hands on those forks and get them sorted, I would do them for free.
Loved these situations before I retired, lads would come in the workshop with this type of challenge.

 

[Deleted member 4366]

This should give you some idea of price. These people will cut off your old chain-stays and weld on completely new ones with the bridge for £150 including VAT. That's for a professional perfect undetectable job, so just to heat up your chain-stays behind the bridge, bend them out and then heat them up again nearer the back and bend them until the drop-outs are parallel should be about £50 - no more than an hour's work for a competent metal-worker. As I said on ES, the most extra that they'd need to do is cut the bridge and weld in a spacer.It's a easy, nothing complicated job. You just need to find a workshop that does welding and fabrication: There's thousands of them. Catch the blokes having a fag outside and they'll probably do it in their lunch-break for a tenner. if you plead poverty or tell them it's for an old lady that can't use her bike anymore because of her bad legs and she's got no other way of getting about.
http://www.argoscycles.com/www/renovation-pricelist.htm

 

[cwah]

I wish you lived near Wigan I'm itching to get my hands on those forks and get them sorted, I would do them for free.
Loved these situations before I retired, lads would come in the workshop with this type of challenge.

Seriously? I wouldn't mind sending the bike to you via parcelforce lol. If you're itching to do that, I can certainly help lol. I'm itching to get it sorted.

 

[cwah]

This should give you some idea of price. These people will cut off your old chain-stays and weld on completely new ones with the bridge for £150 including VAT. That's for a professional perfect undetectable job, so just to heat up your chain-stays behind the bridge, bend them out and then heat them up again nearer the back and bend them until the drop-outs are parallel should be about £50 - no more than an hour's work for a competent metal-worker. As I said on ES, the most extra that they'd need to do is cut the bridge and weld in a spacer.It's a easy, nothing complicated job. You just need to find a workshop that does welding and fabrication: There's thousands of them. Catch the blokes having a fag outside and they'll probably do it in their lunch-break for a tenner. if you plead poverty or tell them it's for an old lady that can't use her bike anymore because of her bad legs and she's got no other way of getting about.
Renovation Price List - Argos Racing Cycles

Thanks Dave, I'm going to visit few more metal shop today. I'm wishing myself good luck lol.