Classic & Vintage - 3 pulley derailleurs

I'm just starting to think ahead a bit and don't know yet if I'm going to be looking for one of these but I'm starting to think I might want one so for now I'm just looking for info ... (ramble off)

How well do the old 3 pulley derailleurs work compared to more normal 2 pulley long cage derailleurs?

I found this image of an example:
http://buggytexas.com/images/belair4.jpg

Are they worth the hassle? Do they work? What problems or concerns are there with using them?

I'd like to build up a loaded touring long distance hill grinder (wide gear range) bike and am starting to think ahead about specific components to use and I just like the general unique and funky look of the 3-wheel derailleur.

Per a discussion I came across on velospace there seems to be a couple of brands or models of these 3-pulley setups so which would I probably be better off with and which should I maybe avoid?

Thanks for any input. I've got no budget to play with right now so now is probably a good time for my research so I won't have any spontaneous temptations before I know what to look for.

Edit to add link to the velospace discussion:
http://velospace.org/forums/discussion/1821/has-anyone-ever-seenused-a-3-pulley-derailleur/

Im in the same boat as you. Just looking for one to try out.

I'd like to try one, but I imagine that I would probably be happier with a Suntour in the GT family on tours. The ability to remove the chain from the RD without removing a link is so darn handy.

Matt

Edit: Another one(from disraeligears).

http://www.disraeligears.co.uk/Site/SunTour_XC_derailleur_%283_pulley_system%29_files/IMGP7090%20%281%29-filtered.jpg

They say that they work very well, and it's a very good design if you ask me. Able to support a large gear range up front without a super long cage. I imagine they are pretty difficult to find.

I have two of them, but have never tried them. The chain wrap listed in Sutherlands is no better than modern long-cages, so I am not sure what makes them better than anything else. Neat looking though.

3-pulley derailleurs were designed to address a specific concern: to create a derailleur capable of wrapping a large amount of chain while maintaining adequate ground clearance for off-road riding.

They do work well, but on the road offer no particular advantage over standard designs.

I have a 3 pulley Cyclone on my commuter. It was a little noisy at the beginning (it was NOS) but it settled in fine. I'm running a 30/40/50 and a 13/21 so it's not really challenged by chainwrap or cog size. I used it just to try it. Works as a Suntour should, great.

I've seen ARX, Lepree and Cyclone models. The XC is new to me. Here's a lousy pic.

https://lh3.googleusercontent.com/__0sZkBzxvxs/TC_z81hI5qI/AAAAAAAAAmQ/bRBPVLsjnfg/s800/DSC04591.JPG

How many of us put things on our bike because it's cool rather than functional?

If I found one, it's going on a bike :D

Especially the LePree ones. Those one ares beautiful.

Edit: *Relatively functional*. Not to say that it's not functional.

I like your LeMond.

The guy at disraeli says they worked great, but they disturbed any onlookers. Personally, i want one pretty bad, for no good reason.

-rob

I know where there's one at a used store around here....don't know the price but...

Interesting. Ask yourself what would be different if the middle pulley wasn't there. The chain would run directly from the idler pulley to the tension pulley and would thus be a bit shorter. The wrap length around the idler would be less, but that wouldn't normally be a critical parameter. (More on that in a moment.) Note that the relative positions of the three pulleys are fixed. So as the cage pivot moves, the total chain take-up is determined strictly by the position of the tension pulley. The middle pulley contributes nothing to the difference between maximum and minimum chain take-up.

From this vantage point it looks like the middle pulley does nothing except reduce the possibility of the chain jumping off the idler pulley, not terribly likely, but maybe this increases its ability to force the chain sideways against a recalcitrant cog.

I know where there's one at a used store around here....don't know the price but...

Let me know what you find out about it, if you can. I'll find one eventually. Just something I want just because I've always been curious about them.

they pop up on ebay from time-to0time, and stay relatively affordable. a rip-off, but not a fortune.

-rob

I own a '85 Nishiki Cresta that came with a full Suntour LePree drivetrain, I was told the LePree was an exclusive for Nishiki and the 3 pulley derailleur was only produced for one year. My personal experience is that it works relatively well and it can wrap large amount of chain. The bike came with a 28T granny gear and the rear freewheel was 14-30.

http://i473.photobucket.com/albums/rr95/orbeamike/cresta.jpg
http://i473.photobucket.com/albums/rr95/orbeamike/cresta1.jpg

That is a pleasant looking bike.

My Nishiki Riviera GT has a full LePree gear system. While I don't notice anything spectacular about the rear derailer, it does everything I ask it to do, and shifts very accurately. Well, like Suntour...