Author Topic: Dragonfly Spoke Length?  (Read 5035 times)

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Offline Les T

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Dragonfly Spoke Length?
« on: 04 Nov 2015 at 07:47 »
Hi, I have a complete new/unused Dragonfly front hub and want to replace the non standard wheel that is presently in the bike. I need to buy a 19" rim and spokes/nipples to build up this wheel but without a pattern I don't know what length of spokes I need to buy. Can anyone help by informing me of the exact lengths of spokes I need, also can anyone recommend anywhere to buy the items from?

Thanks, Les T

Offline eddie

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Re: Dragonfly Spoke Length?
« Reply #1 on: 04 Nov 2015 at 09:09 »
Hi Les,
           There are early and late hubs for the Dragonfly. The early hubs were almost identical to the Mark series hubs whereas late machines had British Hub Co. units. The early hubs had cast alloy brake plates and the spokes were laced conventionally. The British Hub Co units had a steel brake plate with a spun alloy cover plate that hid the ends of the spokes. This resulted in all the spokes on the brakedrum side being laced from the outside inward. To provide a better run for the spokes on that side, the staggering of the dimpling of the rim was changed to one dimple on the brakedrum side and 3 on the other - the brakedrum side spokes going to the odd dimple and the centre one of the three.
 If you have the early type hub, get back to me and I will measure the length of my spokes.
  Regards,
                Eddie.

Offline Les T

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Re: Dragonfly Spoke Length?
« Reply #2 on: 05 Nov 2015 at 07:37 »
Eddie,
Thanks for the reply, mine is the later Brish Hub Co. type which will probably have a different length of spoke to the ones in your earlier hub. I'm changing the front wheel for two reasons, one it will make my Dragonfly more or less completely standard, and two, I want to use the more powerful/efficient 8" brake that is in it at present in another project I am currently working on.

Many thanks for the reply,

Les T.

Offline ian scott

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Re: Dragonfly Spoke Length?
« Reply #3 on: 05 Nov 2015 at 21:41 »
There are many spoke calculators on line https://www.google.com.au/#safe=strict&q=spoke+calculator .

Offline cardan

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Re: Dragonfly Spoke Length?
« Reply #4 on: 05 Nov 2015 at 23:52 »

Just be careful using a spoke length calculator for later motorcycle wheels with big hubs, thick spokes and funny spoke patterns. They will work, but you need to be careful. My understanding of Eddie's description would be that there would have originally been two slightly different spoke lengths on the drum side; slightly longer spokes from that flange to the spoke holes on the other side of the rim. Probably only a couple of mm, but you can estimate it by changing the effective width of the hub.

The BHC Dragonfly wheel would be interesting to build. I'd love to have a go.

I wrote my spoke length calculator http://earlymotor.com/leon/misc/html/spoke.htm in 2000 and have used it many time since, so I know that one works. In 2000, there were only one or two others on the web!!!! By the way, my cat Jazzy died last year, but has been replaced recently by Dijon who continues Jazzy's traditions. Flippy is 17 and a grumpy old lady! (You have to click on the link to understand the cat references.)

Leon

Offline eddie

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Re: Dragonfly Spoke Length?
« Reply #5 on: 06 Nov 2015 at 06:10 »
According to the parts list for the British Hub wheels, all 20 spokes on the brakedrum side are the same. The inner and outer spokes on the other side have different part numbers - presumably due to different angles of the spoke heads - possibly 80 degree for the inners and 100 degree for the outers.
  Regards,
               Eddie.

Offline cardan

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Re: Dragonfly Spoke Length?
« Reply #6 on: 06 Nov 2015 at 07:27 »

Interesting stuff Eddie. Much easier if the spokes are all the same length, and the few mm can be accommodated when wheel building. It would be interesting to look at an original wheel too see if (a) half the spokes have their protruding ends ground back to the nipples, or (b) half the spokes have their ends a couple of mm short of the end of their nipples.

On "extreme" wheels (late model Indians with balloon tyres are an example I've had experience with) the inner and outer spokes are different lengths as well as different angles, because the inner spokes have a noticeably shorter path between the hub and the rim. No such issues for bicycle wheels.

I've always been partial to an 80 Plus, but now I'm leaning towards a Dragonfly with British Hub Co. hubs. I'd need original rims of course! I'm a wheel guy. Do you know I've never seen a Dragonfly in the flesh. Not many out here in Australia I suspect.

Leon

Offline David Lawrence

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Re: Dragonfly Spoke Length?
« Reply #7 on: 06 Nov 2015 at 10:56 »
Hi Les,
Ragarding the British Motorbrake spokes and lacing, Ironically, considering how few drawings we have of the later brakes, we do have the individual spoke drawings and the lacing pattern.
If you care to contact me directly by email we can discuss your needs.
You may already have my address if not message me via the email ikon.
Cheers
Dave

Offline douglas1947

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Re: Dragonfly Spoke Length?
« Reply #8 on: 06 Nov 2015 at 17:09 »
Hi Les,

are you shure you have a 8" British Hub and not a 7"?

If you want the spoke length of a 7" I can measure and send to you.
A rim for a  BSA 7" half width hub will fit to the British Hub.
I have recently respoked a frontwheel 7" BH (for a Panther).

Michael

Offline Les T

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Re: Dragonfly Spoke Length?
« Reply #9 on: 12 Nov 2015 at 11:27 »
Haven't looked at the forum for a few days so thanks for all the replies I'd missed, re the question about the 8" brake, it's the 8" brake that I am replacing with the standard 7" Dragonfly hub/brake.
Again many thanks to all who provided information
Les T

 

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