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Tuesday 26 July 2016

Bike Maintenance

Two problems surfaced during my last run.

1. I lifted the rear of the bike by lifting the saddle ... and the saddle broke. It was still usable, it was just the rubber bushes that damp the suspension that came apart. But it's still a broken saddle. So I replaced it, from the bike that I bought just for spare parts.

At the same time, I remembered that daughter.1 had bought me a kind of saddle cushion. It isn't a saddle, it's a cushion that fits over the saddle, to make it softer. So I put that on, we'll see how it goes.

2. The inner tube rotates inside the tire, which makes the valve sit at an increasingly sharp angle. Eventually, this sheers off the valve, and the air escapes - this actually happened to me twice. I'd rather it didn't happen again.

To deal with it, I deflate the tube, wiggle it straight, then reinflate it. But why does it happen, and why only the rear wheel?

I was out caching yesterday, and I was idly thinking about this and that (caching gives me an opportunity to think deep thoughts) and I realised what's causing this, and why only the rear wheel.

It's my custom to mostly use the rear brake for slowing down - that's because you're less likely to go into a catastrophic skid that way. The brake acts on the wheel rim, putting torque on it to slow me down, but the tire is still trying to continue on its way, as is the inner tube. And the differential between those forces, it what rotates the inner tube relative to the rim.

So now I understand the cause, I can start to think of a more permanent solution than the deflate-adjust-inflate method.


3 comments:

  1. I am tempted by this one: http://www.ebay.co.uk/itm/EBIKE-ELECTRIC-BIKE-1000W-48V-HYBRID-TREKKING-COMMUTER-BICYCLE-CLAUD-BUTLER/322201939921?

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  2. As it says on the Ebay page "PLEASE BE AWARE THAT AS THIS MOTOR IS RATED TO 1000W IT IS NOT TECHNICALLY 'ROAD LEGAL'"

    You can, however, get a motor that is rated to 250W, and which is therefore legal, and "overvolt" it (run it at a higher voltage that it's rated for) which means that it runs at a higher wattage than the rating.

    The bike you want, of course, depends on what you want it for. My bike is used for caching, mostly on grass and mud. So I like the low gear of my motor and I like that it folds.

    I'll be doing a talk on electric bikes at the Geolympix.

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  3. Thanks for the feedback Alan.
    I'd read the "not road legal" warning and option to limit speed.
    I mainly ride on roads / canal tow paths but not much mud.
    For that particular ebay listing which tempted me: I had somehow got it into my head that location was Windsor, but on re-reading it is really Cornwall. So back to the drawing board.
    Do you have a start time for the talk you are giving please - cant see anything on the Geolympix GC5XXYY page?
    Regards,
    Charles.

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