Sunday, 19 June 2016

Royal Enfield Handlebars

As mentioned last time, I've been making some handlebars. Recall that when I last rode the bike, my awesome sprinting prowess bent the handlebars at the stem.


I took a good look at the 'bars and decided that the best course of action was to do nothing to the original set and make a new pair of facsimiles. This way I can keep the original 'bars with the machine should I ever choose to sell it but still be able to ride the machine with gusto and without fear of personal injury.  The original 'bars are of a very fine gauge tubing and are extremely light. They are also rusted through from the inside and after close inspection, I'm amazed that they didn't break rather than just bent. That's one of the advantages of steel components though, sudden catastrophic failure is rare as you tend to get heaps of audible warning before a part fails.

I'm not going to make mine as lightweight as the originals, mainly because I happen to have some chromoly bends left over from the facile project that I can reuse. These are in a thicker gauge which is probably no bad thing. As I discovered when getting tubing bent previously, it is very difficult to get compound bends made in close proximity to each other, at least it is if you want high quality mandrel type bends. So I'm going to fabricate the compound shape of the bars using simple bends joined together. By playing around with the length of the straight portions I can, to a degree, control the style and shape of the final result. I've made some hollow internal lugs from 4140 chromoly, these are a tight fit inside the tubes and when welded up can be made invisible.

Internal lugs ready for assembly.

The inverted front brake lever uses a Bowden cable that runs through the handlebar, this is a very neat feature common to many Royal Enfield models of the early years of the 20th century. My wife's 1903/4 model has a very similar arrangement. The lever is sized to fit inside the thin gauge tubing not my thicker stuff. for this reason I need to chop off the last 2" of the right hand 'bar and replace it with a suitably machined adapter.

Note the last two inches of the right hand handlebar are replaced with an adapter.

I asked Pete to weld up the various parts...

...and as usual he did a wonderful job. 

After normalising the welds, it is an easy job with a file to make the welds disappear. 

I know that filing welds materially weakens the joint but my experience with the facile and the design of my internal lugs means I'm comfortable doing this. I'm confident that they won't be breaking any time soon.

I had previously made the central lug to hold both sides of the handlebars and join them to the steering tube. I got carried away when I machined it and forgot to take any photos of the process.

The steering tube is interesting for several reasons. Firstly the design, notice that the headset, original to the bike, is not a headclip but a conventional design with an adjustable race and a locking headnut,

Steering tube and wedge.

this design means that the steering tube is clamped to the fork via an expanding wedge, the design of the wedge is slightly different to later designs but the idea is exactly the same. I believe that 1906 was the only year that this headset was offered, the years either side used the more standard headclip design. I'd love to know more if anyone has any information. I have a copy of the 1907 catalogue and what I think is the 1905 catalogue but no 1906 edition. I'm lead to believe that the patent number on the steering lock is from 1906. Secondly the OD of the steering tube is not 7/8" as you would expect, 7/8" tube doesn't fit into the forks. I needed to machine the OD down to 0.865" from 0.875" to get it to slip in nicely. Also the ID needed to be thinned to suit the wedge. I didn't want to have to modify any of the original parts that bolt to the handlebars, the facsimile handlebars must be made to fit the original parts.

Next job is to clamp everything in the right places and silver solder the lug. Notice the board that everything is zip tied to, it's the same board I used when I brazed up the facile handlebars. Spooky.

Ready for silver soldering.

Finally I just need to clean up the joints a little and check for fit in the bike, I'll plate them when I plate all the other parts I'm working on at the moment.

The shape and dimensions are extremely close to the originals, I'm quite pleased with them.

Don't you just love the Edwardian racer look?

In other news, I'm having some other frames professionally painted at the moment. I'm slowly getting my list of projects down so that I can start work on the racing penny farthings. These frames have been on my list for ages and I want to get both bikes back on the road before I start. More later.

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