Monday, 27 February 2012

Update on Peugeot Lautaret Project

I've decided to build up the Peugeot Lautaret as a single speed. No dangly mechs or levers! Opting for freewheel, not fixed. Here's a photo:
I sprayed frame saver inside the tubing. The HLE tubing material is interesting (those d/t levers will be coming off btw):

It's Peugeot own brand "Haute Limite Elastique". A USA 1987 Peugeot brochure that I found online describes it as follows:

"HLE Tubing: HLE is Peugeot's exclusive alloy tubing. It is a "micro alloyed steel" which is comprised of Manganese, Niobium, Aluminum, Carbon and Titatium[sic], which offers a lighter, yet stronger frame. These elements are commonly used in the production of aeronautical steel. The introduction of these elements results in a steel with dramatically improved mechanical properties when compared with more conventional steel. The strength to weight ratio of HLE tubing is far superior to that of conventoinal tubing. Using this tubing enables Peugeot to save more than 7 ounces in the weight of the frame. The HLE tubing, when used with our patented internal brazing system, gives Peugeot a frame which is at the top of its class in performance and reliability."

As best as I could measure it, the seat tube inner diameter was 24.0mm. An odd size, and I could find no post to fit. So, I obtained a shim with 1.8mm thickness, to narrow the internal diameter to 22.2, the rationale being that this is a more common size for seat posts. Here are some photos (the shim is a black, USE brand):
Since the shim was for a larger diameter, I had to trim it along one edge and squeeze it in:
I have a cheepo 22.2 steel seat pin, and it fits beautifully. I may try to find an alloy one. The seat post clamp is a traditional steel nut and bolt type, which is less likely to damage a steel one when tightened.

I have a solution for the steering end. I sold the quill stem that came with the frame because modern handlebars didn't fit the clamp. It went on fleabay for £5.99. Since I bought the whole package originally for £13.10, that means the frame cost me £7.11! I got hold of a 11/8-22.2 quill-Ahead adapter. Luckily the adapter tube fitted perfectly inside the steerer, but the expander wedge was a bit too wide (probably 22.2). As the wedge was alloy, I was able to reduce it to fit using AlOx paper. The stem is a modern type from M:part, with a 25.4 clamp, perfect for the handlebars.

Here is a summary of what I've been mulling over. Over the last few weeks, it was useful that I spotted some 1980s racing bikes parked in public places that had been converted to s/s. I've seen three different approaches:

1. Replace the multi-speed freewheel with a single speed freewheel, simply screwed on to an old style threaded wheel hub. Predictably, with a single chainset, the chainline is rather angled. It was not a very good solution for one of the bikes I saw. It could be made to work if the freewheel was shimmed out a bit, and at the front, one could use a shorter BB axle length and a different chainring that fits to yield a shorter chainline (that is, closer to the seat tube). One bike I saw achieved a good chainline by using the inner ring of a double chainset up front.

2. Keep the screw-on multi-speed freewheel, and use a single chainring at the front. I guess one selects the sprocket that gives the best chainline, so it may be a lottery to get a useful gear ratio. The one I saw had a super straight chainline. Not bad and a cheap solution. But the 6 speed freewheel is a heavy-ish rotating weight, five other cogs are spinning around unused. Not so elegant!

3. Use a modern cassette hub wheel, shim it up to take a sprocket on the back, with a single chainring up front. This is less dependent on the chainset and BB, as the back end sprocket position may be adjusted with shims.

I've bought my chainset, because it was a total bargain and suited a Shimano UN54 113mm square taper BB that I have in my spares box.  It's a Sturmey Archer single with 44T.  When I fit it I'll measure the chainline first, so that I have a reference to work from. It could be that Option 1 may not be possible. We'll see. I appear to have all the parts needed to try each of the above solutions.

Interesting thing is that standard 130mm rear hubs fit with just a slight hand springing of the rear dropouts. I guess it's only 2mm each side that needs to be sprung! The HLE rear stays are rather more flexible than those on modern frames. I'm guessing the ride will be soft. Anyway, next steps are to service the head set, fit the BB and shine up the frame with car polish...Photos later as I progress.

Velo Solo - A totally brilliant website for riders interested in single speed conversions. The online shop has superb photos, so that you can see exactly what you're ordering. Really worth visiting, even if just for idea-generation.

1 comment:

  1. Do you subscribe to any other websites about this? I'm struggling to find other reputable sources like yourself

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