Derailleur on Thorn Raven?

[horizon]

This must sound a very obvious question but I cannot find an answer to it. Is it possible to put derailleur gears on a Thorn Raven frame? I only ask as it seems Raven frames do come up second hand and more often than Sherpas. (I don't want a Rohloff). Thanks.

[Dave Whittle Thorn Workshop]

Its not possible, the dropouts don't have a gear hanger, the Eccentric has the wrong offset from the seat tube, and the cable guides are in the wrong places.

Sorry to disappoint,

Dave

[horizon]

Thanks very much for for that Dave. I didn't think it was possible so it was only a passing thought but I did come across this:

I came up with a somewhat different solution to the OPs problem
He wants a cheaper robust alternative , but cant use derailleurs on a Thorn frame - in fact you can. I built a Raven like this using a Shimano Hone hub. This looks standard and is the correct width, but doesn't have a Quick release. There is instead a long bolt all the way through the axle and the special bit is that this also clamps on the Hone rear der. without needing to add a mount on the frame. Strong secure mount, I then used a full length outer up to the shifter as the Thorn frames don't have cable stops.
Don't know if Shimano still make them, but I would be prepared to swap the wheel for your Rohloff , just to help out of course!

Here's the link:

http://forum.ctc.org.uk/viewtopic.php?f=5&t=85265&start=30

I'm not interested in going down that route, I'm only interested if a straight swap were possible.

[mickeg]

I am not sure but I think Dan might have found a Wheels Mfg hanger that could be used on the Nomad dropout to fit a derailleur?

[triaesthete]

What size Sherpa do you want 

[horizon]

A 565S (or 560S) in red. The Raven frame and forks was £200. You can see the attraction...

[martinf]

It would be possible:

- gear hangar clamped on solid axle rear hub.
- maybe problems for fitting multiple chainrings in correct position.
- maybe problems for fitting a front derailleur in correct position.
- cable stops for derailleurs not fitted so fully enclosed cable runs (not necessarily a bad thing IMO).

So more of a bodge than using a Shimano gear hub, and IMO better to use a Sherpa frame or other derailleur-specific frame. I used an old steel mountain bike frame with similar geometry and weight (but not strength) to the Thorn Nomad for my Spain tour, it performed very well.

If Rohloff too expensive, I reckon it would be better to use a Shimano hub gear on a Raven.
Alfine (8 or 11) or Nexus 8 will fit, not quite as neatly as the Rohloff the frame is designed for.

I noticed very little difference in efficiency doing a conversion the other way (on my old mountain bike after my Spain tour - 3x7 derailleur to Nexus 8 Premium). I reckon this is a good alternative to a derailleur and to Rohloff if you don't need too wide a range - 8 speed Nexus is sufficient for me for local use.

[rualexander]

A few years ago there was a guy on ebay selling some Raven frames with a derailleur hanger welded onto the dropout

[horizon]

Thanks for all the replies. It seems the simple answer to my question is No (which is what I had thought) but it's nice to be sure. I get the impression that Ravens come up for sale quite often but Sherpas don't (this could be perception bias though!). I wonder how many Sherpas Thorn sells compared to Ravens and whether people sell their Ravens but hang on to their Sherpas. There may be a sound reason for this: perhaps Rohloffs are bought for a specific trip then sold to recoup the high initial outlay while Sherpas are bought and retained as cheap regular bikes. Who knows...

[Pavel]

Why not a shimano internal hub.  Quite economical and less blasphemous.   

[horizon]

Why not a shimano internal hub.  Quite economical and less blasphemous.   

All the usual reasons: want the gear spread, want to keep it simple, want to keep it cheap, want to keep things interchangeable across bikes. Rohloffs give you the gears and IMV are reliable etc etc but I do like to get closer to the workings of a component than you can with Rohloff (and to keep the costs down!). So yes, if someone handed me a Raven I might try a Shimano hub but my preference/strategy is for derailleurs (for better or worse).

BTW, I've nothing but respect for Rohloffs and would think of one for a tandem. But they aren't for me.

[Pavel]

The other thing to consider is that the front is set up for a single sprocket.  I imagine that one has to figure out if the chainline needs to be changed for a double or triple and how small a ring will fit.  The guides for a front derailleur should I imagine not be hard to find which can be put on.
To tell you the truth, it is sounding a bit like a kludge doing this retro-fit.  If it were me, I would take the frame and trade it in for one which was set up with detailers in mind in the first place. The Raven frame is likely to be worth quite a bit more than the average frame - you could come out ahead in a trade.

[brummie]

Its not possible, the dropouts don't have a gear hanger, the Eccentric has the wrong offset from the seat tube, and the cable guides are in the wrong places.

Sorry to disappoint,

Dave

Been meaning to post this for a while, just took some finding ! http://commons.wikimedia.org/wiki/File:Two_Thorn_Nomad_bicycles.JPG

[Danneaux]

My! You surely did well to find that shot,  Brummie!

Clever routing of the front derailleur cable....

All the best,

Dan.  (...who has an emergency derailleur hanger in his spares box that would do the job)