Wednesday, 14 November 2012

Handlebars - take 2

I have recently been introduced to an excellent young fellow known as Tweed Pete. Tweed Pete likes to tinker with old bicycles, indeed he is making one of these...

This is taken from Andrew Ritchie's Blog.

...and making a fine job of it too. 
This is his MkI, an improved MkII is already in the planning stages. 

In his own words, "old bicycles have bitten me pretty hard". Saying that Pete has a big shed would be a little like saying that Christchurch has had a few earthquakes. It is a most impressive shed, containing large amounts of spares parts and materials that will be useful for future projects. Or 'some old crap' as my lovely wife would call it. Like any normal man, I thoroughly enjoy poking around in other people's sheds. I'm trying hard to reduce my list of 'future projects' and I suspect that Pete is doing the same. He appears to be better at it than me as the last time I visited, he managed to get a couple of spare 1/4hp Crompton Parkinson electric motors in the boot of my car without too many complaints from me. I'll get my own back next time he comes round.

Tweed Pete recently put me onto a new source of chromoly tubing in NZ, the USP being that they sell the stuff by the foot, rather than only a complete 18' length. I found them easy to deal with and in just a few days I came home to a shiny length of plain gauge 0.75" x 0.049" chromoly tubing sitting on the doormat.

I've going to try a change of approach with making the handlebars. I have experimented and racked my brain (didn't take long) for a solution to my problem. Indeed, I've even had real engineers racking their brains to solve my problem. Engineer Dylan is another excellent young fellow that has contacts in the real engineering world. He has suggested that I get the tubing spun to produce the taper. Btw, it's worth watching that video, if only for the bloke's accent. Spinning is a bit like magic, I still don't understand it. I took my tubing to see a local spinner in his shed and he believes he will be able to do the job, The downside being that I will have to make a mandrel and I still have the problem of bending the finished tapered tubing. So before I go any further down that route I'm going to try something else.

Of the various original machines that I have seen or have seen photographs of, the handlebars fall into two distinct types, deep or shallow drop, with either pear or T grips. My dodgy back tends to prefer a more aggressive position on a bike so I'm going to be making my handlebars with a deep drop and T grips. The same as the Welsh and Austrian[1] bikes.

I've taken the plain tubing to a recommended tube bending company along with an accurate sketch of what I require.

The first attempt didn't go well as the chromoly didn't like the sharp bend.

We changed to a larger radius and all was well. 

It is interesting to note at this point what a high quality mandrel 
bend looks like like compared to a poor quality bend.

Actually that's a little unfair since to see a really bad bend you'd need to go and see Mr. Middleton.

Next I cut a sliver from the underside of the handlebar.

 I drew the shape on masking tape on a flat surface...

 ...and then transferred it to the tube.

Everybody should own a Dremel tool.

Cutting this sliver proved slightly tricky because I couldn't get in for the full length with the hacksaw. A Dremel with mini metal cutting discs made short work of this and I was able to get an accurate slice removed.

Next the gap was squished closed, this is a simplification since it is important that the round profile is maintained for the length of the taper. Simply squishing the gap would result in a sharp V at the joint, not satisfactory. Also the springy nature of the 4130 made this an interesting exercise.

Squished gap.

Then take the squished tubes into Christchurch to go and see Pete the welder again. Pete is one of the few people that I am confident outsourcing work to, I know from past experience that he understands my level of desired quality and he always delivers.

Welded gap.

I ran a little silver solder down inside the ends to disguise the inner seam of the weld, at the same time I normalised the weld zone since these will be repeatedly under stress cycles. Time will tell if they prove durable.

Finally dress off the welds and cut to length. 

Now we can see what the finished profile with a dry fit of all the parts so far. 
I can see a brazing day in my near future.

These handlebars have been something of an ordeal to make, probably the item that has caused me the most difficulty so far. Certainly they have proved very costly in terms of time and money, I am glad that they are done.

In other news, some weeks ago I read with great interest that the SOLO project has officially gone live. SOLO being "Search Oxford Libraries Online". And as everybody knows, The Bodleian is an Oxford library. I'll leave it as an academic exercise for the reader to find the appropriate link but suffice to say, there is now a wealth of down loadable material at your fingertips. For example, I have increased the number of Bicycles and Tricycles of the Year (Harry Hewitt Griffin) in my collection from 7 titles to 12 as a result. Happy hunting. Incidentally, last year I had a very rare opportunity to purchase an original pair of H H Griffins from 1883. They are both in excellent condition and in due course I will be duplicating them for general consumption. I had never previously seen the copies from 1883 before and I was tickled pink to find them. Coming soon to a blog near you...

[1] Thanks to Christian R. Conrad for correcting me. I erroneously assumed that it was in Germany. It isn't.  For some reason I am unable to respond to comments, I'll need to investigate this. But thanks, I do appreciate the information.

1 comment:

  1. Fantastic looking handle bars and enjoyed the info on how they were made. I have entrusted my customers engineer in Tokyo to bend the bars which are solid and weld them into the steering head on the replica ordinary that I am building , I have the T grips already made so I hope the bars turn out ok. Off to NZ this Friday for 2 weeks but will not have any time in ChCh , maybe we will meet up in the future. Keep up the great work.

    Don Speden
    Furumachi Bicycle