Author Topic: Dragonfly Sprockets  (Read 2045 times)

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Offline Les T

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Dragonfly Sprockets
« on: 15 Jan 2015 at 08:12 »
I'm thinking of attaching a sidecar to my Dragonfly and can foresee that I may need to lower the gearing to suit, does anyone know if gearbox sprockets are available with less than the standard 16 teeth? If not does anyone have an old sprocket I could use to turn the teeth off in my lathe and then graft on a sprocket with a smaller number of teeth Thanks Les T.

Offline eddie

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Re: Dragonfly Sprockets
« Reply #1 on: 15 Jan 2015 at 13:22 »
Les,
       The standard gearbox sprocket has 17 teeth - the 16 tooth you have is from either a 90+ or Competition Douglas. Unfortunately, because there is a shock absorber incorporated in the sprocket, it is not possible to go any smaller without the chain fouling the shock absorber boss. If your machine is one of the later type Dragonflies fitted with British Hub wheels (the ones with the pressed alloy covers on the brakeplates), it will have a bolt - on rear sprocket, which could be changed for one with more teeth. The only other modification needed will be to raise the back of the chainguard to give more clearance.

  Regards,
                Eddie.

Offline Les T

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Re: Dragonfly Sprockets
« Reply #2 on: 16 Jan 2015 at 05:34 »
Thanks Eddie for the useful information, I didn't know about the shock absorber in the gearbox sprocket but had foreseen having to raise the chainguard if a bigger rear wheel sprocket was fitted, plus I may have had to lengthen the chain.

Offline David Lawrence

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Re: Dragonfly Sprockets
« Reply #3 on: 16 Jan 2015 at 14:50 »
Hi Les,
Just a follow up on your Dragonfly drive sprocket, are you sure yours is fitted with a 16 tooth sprocket, as Ed says the standard was 17, 16 were quite difficult to come by.
The Douglas Club spares has an order for sprockets in at the moment, we are having both 16 and 17 teeth manufactured, (also mark chain sizes as well!) delivery should be early Feb.
Dave.