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Questions on Suntour LePree 3-pulley RD

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Questions on Suntour LePree 3-pulley RD

Old 02-01-22, 10:02 AM
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GameboyRMH
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Questions on Suntour LePree 3-pulley RD

Hey all, signed up to ask some questions here because I'm trying to fit a 3-pulley LePree (or at the very least, the cage from one) to my fairly modern MTB with a 3x8 drivetrain for very functional reasons - improved ground clearance, reduced chain slap, and that huge chain wrap capability. I'm really pushing the limits of a Shimano Tourney TZ right now and might be looking to increase range further, and there seems to be a lot of knowledge on these ancient RDs in here. So my questions are:

1. Does anyone know if this derailleur can work with an indexed shifter (Shimano in particular)? If not, what is a good candidate to swap the cage onto to achieve this? Could even be something modern, function comes first.
2. Does anyone know how it works with very small sprockets on the rear, like down to 11t? From pics I've seen it looks like the upper jockey wheel runs at a fairly large distance from the cassette.

Thanks
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Old 02-01-22, 06:54 PM
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As much as I like these kinds of fun challenges, I doubt you'll get it to index with anything, but I haven't tried myself.

Are you running a bike with very small diameter wheels? The Tourneys are fairly low-end. Perhaps a higher-end modern 8 speed RD would solve some of your problems, except the ground clearance. I've had a Shimano Acera that was new some 8 years ago that just worked great and never needed much attention, but that was on a 700c touring bike that didn't go off road much. I still have it kicking around here waiting for the next project.
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Old 02-01-22, 07:14 PM
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The bike has 26x2.4" tires which may be small by modern standards I'm actually eyeballing a Shimano Acera as a fallback option if this doesn't work out, it does have more wrap capacity than the TZ and even a hair more than the LePree, although this comes at the cost of even less ground clearance.
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Old 02-01-22, 08:49 PM
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3 pulley models aren't known to index well with anything. I had no problems with a 12 cog, never tried an 11.
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Old 02-01-22, 09:35 PM
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Why paint yourself in a corner with 'indexing' and ShimaNO ?

Simply use the 'thinking man's' shifting system = FRICTION ! ....the MOST VERSATILE shift system ever made !
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Old 02-02-22, 07:45 AM
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I do prefer indexed shifting, and although I might consider friction shifting for some applications, for my MTB indexed shifting is a must, the terrain can give you plenty enough to think about!

So it sounds like a cage swap will be necessary, are there any similar models with a Shimano-compatible shift motion ratio the LePree cage fits well onto? I suppose that might only happen by chance because this RD is from an earlier era. One slightly wackier idea would be to add some kind of custom adapter plate to the parallelogram body which would allow the ratio to be adjusted. When the LePree arrives here I'll do some tests and see how far off it is.
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Old 02-02-22, 07:54 AM
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Trying to put a Suntour 3 Pully cage on a Shimano body is likely more than difficult and a waste of your time. Those cages are difficult to swap over to other Suntour bodies...only a few are compatible.

There's lots of 3 pulley discussions on these gears, use Google to find them and not the BF search engine.
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Old 02-02-22, 08:48 PM
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Originally Posted by GameboyRMH View Post
So it sounds like a cage swap will be necessary, are there any similar models with a Shimano-compatible shift motion ratio the LePree cage fits well onto? I suppose that might only happen by chance because this RD is from an earlier era. One slightly wackier idea would be to add some kind of custom adapter plate to the parallelogram body which would allow the ratio to be adjusted. When the LePree arrives here I'll do some tests and see how far off it is.
Originally Posted by clubman View Post
Trying to put a Suntour 3 Pully cage on a Shimano body is likely more than difficult and a waste of your time. Those cages are difficult to swap over to other Suntour bodies...only a few are compatible.

There's lots of 3 pulley discussions on these gears, use Google to find them and not the BF search engine.
^ truth.

I think it's important to note, while Shimano was perfecting indexed shifting and the adoption of the the slant parallelogram- Suntour was trying to figure out how to go over rocks.

The Suntour triple pulley arm was developed around a friction system; one might even say 'in spite of an indexed system.' It was never implemented on an indexed system- the triple pulley elbow was abandoned to focus on Accushift. In the various units it was installed on, some did have cable tension nuts- and might be able to eke out passable indexing- but it would be completely by accident. Depending on the model, you can try wrapping the cable the "wrong" way around the cable anchor to change the actuation some. Again- it would be completely by accident.

I have a triple pulley XC derailleur- it's probably the nicest shifting Suntour I have- but it is kind of a tank. Yes- that triple pulley elbow wraps a few yards of chain- and it's a legitimate idea that ran alongside the "Tech" stuff, the outrageously long cages and the 15 tooth pulleys. I evaluated how I could get a triple pulley cage to work on other derailleurs and came to the conclusion that it wasn't worth it to me- I'd have to find the right body, with the right attachment point- and that's just to get the thing installed- not actually having it work..

If'n it were me- looking for extra ground clearance on a Shimano SIS system, I would be looking at one of the short cage 15 tooth pulley derailleurs. I think those were the Altus, Alivo and Tourney. And Dura Ace.



Originally Posted by TPL View Post
Why paint yourself in a corner with 'indexing' and ShimaNO ?

Simply use the 'thinking man's' shifting system = FRICTION ! ....the MOST VERSATILE shift system ever made !
There's a point where you just want stuff to work and not have to **** with it.
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Old 02-03-22, 09:53 AM
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A good modern option I found the other day is the SunRace RD-M900 - works with Shimano indexed shifters, has a clutch to reduce chain slap, even the medium-cage model has plenty of wrap capability, and being direct/shadow mount also helps keep it out of harm's way.
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Old 02-03-22, 10:59 AM
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Please don't sacrifice this relatively rare derailer to any weakly-designed experiments.

Early Suntour and Shimano derailers from before the indexing era all move further in response to any given cable movement, just like any Shimano Dura-Ace "SIS" rear derailer from before 1997 (pre-9-speed in other words).

So, apart from using actual Dura-Ace shift levers with these pre-index derailers, one can use a 7-speed Shimano shift lever and it will index the movements well across a standard-spaced five or six-speed freewheel, due to the greater cage movement.

One can also simply(!) use any (other than 3040 series) Suntour indexed (i.e. Accushift) shift lever together with a freewheel having the same intended gear spacing, i.e. using a 6s or 7s Accushift lever with a 6s or 7s freewheel, respectively! This will also index correctly.
(Suntour indexed rear derailers are just like the pre-9-speed Dura-Ace rear derailers in this regard),, ...(model 3040 excluded, it's more like other Shimano indexed rear derailers)

None of the above will assure good shifting quality. Choice of chain, freewheel and freewheel size, in addition to careful chain gap setup and especially cabling performance, will determine to what extent that correct indexing motion actually delivers on "good" shifting performance.

Above comments made by clubman are spot on imo, so I would firstly keep the subject test unit intact (Shimano rear derailers depend on an offset top pulley, which the Suntour cage does not feature!).

I would not sacrifice this derailer to rough off-road use myself, and I doubt that it will solve any problems that a newer indexing derailer can't deal with.

As noted, older derailers from the pre-index era typically do not track the smaller end of the freewheel well at all, meaning less-than-responsive shifting often result (the Huret DuoPar, Shimano Superplate and Suntour Mountech are notable exceptions).
Use of modern chain improves smoothness greatly, but only exacerbates the chain gap excess because of the newer chain's increased lateral flexibility.

Use of a freewheel/cassette having a very large spread of cog sizes, together with a vintage derailer, will make adjusting the chain gap properly virtually impossible in most cases, in my experience.

It's always fun to experiment however, we all enjoy reading about how other's experiments turn out!

Last edited by dddd; 02-03-22 at 11:23 AM.
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Old 02-03-22, 11:05 AM
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Originally Posted by TPL View Post
ShimaNO ?
Now THAT is funny!

That said, yeah, I know a vast number of happy users for the brand out there.
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Old 02-03-22, 11:06 AM
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Oh I definitely won't do anything irreversible to the LePree. If I end up selling it I will post here in case anyone is interested.
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Old 02-12-22, 08:05 PM
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So I got the LePree a few days ago, today I bench-tested it with a Shimano 7-speed indexed shifter with the cable attached to the derailleur in the normal position just as a baseline test, and...immediately it looks like I might be in luck! The movement is close to 5mm per shift. Next I'll unbolt my current RD from my MTB and try the LePree on there to confirm that it lines up with the sprockets and can reach 1st and 8th - it looks like every last bit of the movement range will be needed to reach all 8 sprockets. If that looks good, the next step will be to run the chain through it and test it with the bench-rig 7spd shifter. Finally if that works well, it will be time to commit and put the LePree on the bike properly to see how it runs with the 8spd shifter.
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Old 02-13-22, 12:02 PM
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You know this half-baked plan might actually work? Range looks good too: youtu.be/2GJ1RMjeYWk
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Old 02-13-22, 01:57 PM
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So I've run the chain through it and I've been trying to see if the shifting can be perfected. it's at the point now where it generally goes into the right gears, but with the best tension setting I've found so far, the chain is hesitant to move to the next sprocket - in either direction. Possibly because the uppermost idler wheel is running pretty far from the sprockets, even with the B-tension at zero. If I change the tension one way or another, the shifting becomes good in one direction but worse in the other.

Ideas?
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