H: Hubs, Wheels and Tyres Rear Sprocket

[highbury731]

The rear chain guard is quite good on my Vincent Rapide but a little project I had in mind for quite a while was to devise a small guard to protect the bottom run of the chain. An Ariel Square Four I bought in 1969 had a small guard for the bottom chain run that thought was a good idea.
Quite a few modern bikes have plastic chain guards, they are light and don’t need painting. I had an offcut of black plastic drainpipe in the shed so I thought I would experiment with that. I cut off a short piece and warmed it with a hot air gun and then gradually squashed it in the vice between two lengths of wood to see how easily it would form. The first photograph shows how it turned out. Next, I cut a piece of pipe and slotted it lengthwise. I warmed it and when it became pliable I flattened it out. I found a piece of wood of a thickness the same as I wanted for the inside width of the guard and rounded one edge and then used this as a former to bend the hot plastic over to give me a “U” shaped piece. I cut this to the length required and used a piece of thin stainless steel sheet to attach it to torque arm of the right-hand rear brake. The other two photographs taken from the left and right-hand sides, show the guard fitted.
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I am keen to make one for myself.
Am I right in thinking that this is a plastic downpipe for guttering, 70mm diameter? I have obtained an ample length of that.
How wide is your guard? The photos suggest a simple curved radius at the top. It looks to me as though your ss mount bracket attaches to two bolts unrelated to the torque arm mount and the FT134.
Paul

 

[highbury731]

Police car parked and as I passed turned his blue lights on, so stopped left the bike ticking over while we talked and told him that they had been fitted for 15 years and had been all over Europe and never been pulled over, he took photos of me & bikes my WOF and tax sticker and never heard anything more, probably muttering about bloody limey's though.

Bananaman.

Kiwis (and Aussies) refer to English pople as 'poms'. Limey is a US term.
Paul

 

[vibrac]

I like that deformed pipe idea thanks Ed. I have a classic bike with no available chain guard and as the owners club does not have a spares supply like VOC the next batch "will be ordered soon" a plastic one would be a fine idea for the long wait

 

[BigEd]

I am keen to make one for myself.
Am I right in thinking that this is a plastic downpipe for guttering, 70mm diameter? I have obtained an ample length of that.
How wide is your guard? The photos suggest a simple curved radius at the top. It looks to me as though your ss mount bracket attaches to two bolts unrelated to the torque arm mount and the FT134.
Paul

Dear Paul,
The pipe I used is an offcut of uPVC black plastic that is used for guttering and downpipes. Probably from Screwfix 68 mm diameter, under a fiver for 2.5 metres but it sounds as if you got what you need. My guard is approximately 35 mm wide, the same width as the steel upper guard. If it is pipe not gutter cut a piece a little longer than the length of the guard you want to make and then slit it longitudinaly. Warm the pipe hot air gun or oven if your wife is out, (bachelors can discount this) and when it is pliable all over pull it as flat as you can by hand, lay it on a flat piece of wood and put another flat piece of wood on top and press it down until it cools. (You could use flat metal but this is likely to take away the heat too quickly To make the "U" shaped section warm a straight line down the centre and fold it over a round section of a diameter a little under the inside width you want for your guard. (Wood is best if you have something suitable, e.g. broom handle) The actual size is not critical and you can easily trim the length and shape it with a hacksaw, file or sander.
I fixed it to the torque arm with a couple of small bolts and the bracket was just a piece of flat metal. You may need to tweak your piece of metal a little or use a few washers as packers to get the chain to run down the centre.

 

[Vincent Brake]

To Robert, indeed its abrasive wear and tear, only hardness helps in such a case.
As does the new beemer chain type with DLC coatings.

I use aluminium, and indeed after 7012 mls its totaly bust, not the chain though.

Now I turn them arround at 5-6000 MLS and the life is double.(idea came from someone here)

Yes I also turn around in my bed at night.....

 

[Robert Watson]

Vincent My recent batch of hard sprockets (in 520 chain 46, 47 and 48T only) are made from 4140 and salt bath nitride hardened at 1000 deg f so no distortion. they claim around RC65 10 - 13 thou deep.

But they are pricey and only useful for you and I doing high mileages -- well me not so much right now!

As for chains it seems I get maybe 15 - 18 K and then suddenly a few links get really sloppy as the seals fail. Pretty much more than 1 click or two on the adjusters and the chain is done.