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Bikes For Sale / Re: 2004 Thorn Raven Rohloff For Sale
« Last post by Andre Jute on August 13, 2026, 09:24:02 PM »
Joe's photographs remind me how much I loved that biplane fork...
Interesting - why?

I answered Andy's question in new thread "On the biplane crown: what does it add to the bike's stiffness?" at
https://thorncyclesforum.co.uk/index.php?action=post;msg=117250;topic=15757.0
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Not sure I understand all of that…..but the basic problem with the longer biplane fork for me was that it raised the bottom bracket height too much.  The alternative 40mm shorter Thor fork I now use allows me to have the correct pedal - seat distance and still be able to get a foot safely down when stopping.  Essential on sloping ground and when carrying luggage.  I am sure both fork types are well strong enough for my riding speeds and style!
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Bikes For Sale / Re: 2004 Thorn Raven Rohloff For Sale
« Last post by playlord on August 13, 2026, 08:39:07 PM »
Size is 537L.

Thanks for moving this, Danneaux.

Best wishes
Joe

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Joe's photographs remind me how much I loved that biplane fork...

Interesting - why?

Partly aesthetics: the biplane crown looks good and adds interest to the frame. It's also good engineering in that the wider and deeper crown, fixed three times along its length across the bike and another three times on the second plane, adds considerable stiffness.

I changed mine to a shorter Thorn steel fork as that design of fork was too long for me.

A shorter fork with a single-level crown would by the dimensions be stiffer than a longer crown of the same material and general construction. The twisting force on a fork, say cornered hard on a twisting downhill would have a lever arm of the length from the centre of front axle diameter to where the head tube meets the crown, with differential loads on the two legs of the crown. In the turn the outside leg will be less heavily loaded and perhaps would offset some of the stress on the crown bearing. With a loaded bike with lowriders the panniers would add stress, but with a shorter lever-arm from the mounting sockets of the lowrider frames to the same crown race/head tube interface.
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Bikes For Sale / Re: 2004 Thorn Raven Rohloff For Sale
« Last post by playlord on August 12, 2026, 11:31:53 PM »
Thanks All.  Will get that frame size tomorrow and post.

All the best.
Joe
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Bikes For Sale / Re: 2004 Thorn Raven Rohloff For Sale
« Last post by Andyb1 on August 12, 2026, 10:45:44 PM »
Joe's photographs remind me how much I loved that biplane fork...

Interesting - why?
I changed mine to a shorter Thorn steel fork as that design of fork was too long for me.
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Bikes For Sale / Re: 2004 Thorn Raven Rohloff For Sale
« Last post by Andre Jute on August 12, 2026, 10:29:28 PM »
Joe's photographs remind me how much I loved that biplane fork...
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Bikes For Sale / Re: 2004 Thorn Raven Rohloff For Sale
« Last post by in4 on August 12, 2026, 06:18:04 PM »
Do you know whar frame size it is, Joe? Usually stamped into the frame, under the BB.
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Bikes For Sale / Re: 2004 Thorn Raven Rohloff For Sale
« Last post by Danneaux on August 12, 2026, 06:06:02 PM »
Quote
Pics attached. Limit upload is 4.  Let me know if you want more specific ones taken or the pics emailed in higher res.

Excellent photos you've posted, Joe, and you're welcome to post more.

The limit upload is four per post, so another post would net you another four photos, and so on.

Best of luck on the sale,

Dan.
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Thorn General / MOVED: 2004 Thorn Raven Rohloff For Sale
« Last post by Danneaux on August 12, 2026, 05:51:54 PM »
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