Three weeks after our accident, I’m pleased to report the Sunbeam was back on the road.
Although I was very relieved at how minor the damage was to the old bike, considering the circumstances, I was still very disappointed about the handlebars. They were so badly bent that the front brake cable that runs up the middle was squashed flat. Original Sunbeam handlebars are difficult to find – being the first thing that goes in an accident and although I was offered some reproduction ones, on an original paint bike I was sad to lose the bars that had been on there for the last 82 years.
When the bike was still in the in the back of the van on the Island, my mate Richard – who’s a clever sort of chap – looked at them and reckoned with the facilities at his work, they could be repaired. It seemed unlikely to me but gave me hope. Returning home, I decided the first thing to do was get them off and assess the situation.
Don’t look good do it?
The first step was to remove the brake cable, which I did by mounting the bar in the vice and heaving gently until it strightened just enough to release the grip on the cable. Clearly attempting to bend it any further cold would have seen cracks starting to appear so if it was going to straightened at all, it would need heat and lots of it.
One solution would be to heat the whole area red hot, pull it roughly straight and force a bar up the middle to reform the tube, bending the proper curve back into it later – but I tried something like this on a tube once before and it didn’t work. It’s too easy to puncture the tube with the bar, ripping the side out of the bend and the ‘cold’ bar tends to cool the tube removing its flexibility. Red heating the whole bend would make it easy to straighten but it would still be flat… How could I actually re-form the tube? I decided I’d use the oxy-acetylene torch to heat the back of the bend and the two edges, leaving the front of the bend – the kneecap if you like – (relatively) cool. My thinking was that this bit was the least distorted and if it retained its rigidity it might provide a sort of ‘backbone’ to pull the other three sides back into shape. I kept gentle pressure on the bar with my hip while playing heat continually onto the three areas and was absolutely delighted when as the bend straightened, the shape of the tube slowly came back.
Sorry about the crummy focus but hopefully you get the idea. The tube was left a bit oval but pressing it between some old handlebar clamps dealt with that and you’d never guess how bad it had looked ten minutes earlier.
Now I know many people won’t like the sound of straightening badly bent handlebars and I guess I should stress that this is a repair made at my own risk, using my judgement and experience; don’t try it at home and I’m not recommending it as a textbook repair. On the other hand, the bike isn’t a motocrosser, I don’t try to pull wheelies and the front brake isn’t likely to offer the opportunity for an ‘endo’. I’m satisfied that slow cooling will have annealed the ductility back into the steel – and I’ll be keeping an eye on it.
The rest of the straightening operation was much gentler. Heating the inverted brake lever enabled me to straighten that, the same with the kickstarter and footrest and now, apart from the extra dent in the tank, the old girl is back together again.
I’m pretty sure the cause of the accident was the rear tyre creeping round the rim until it ripped the valve out. The pressure had been a bit low earlier in the day and that combined with the take off and touchdown you get on a rigid framed bike on bumpy roads must have been just enough to pull the tyre and tube around until the valve could no longer restrain it. These days I habitually back the locknut on the inner tube valve right off up to the cap so any movement of the tube is revealed by the angle of the valve, giving a ready check. It’s a long time ago I fitted the Sunbeam’s tyres and I didn’t do it back then. Live and learn…
R
