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Old 11-03-05, 10:31 PM   #1
Mentor58
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Hey Gang,

If you use a MTB rear derailer, you MAY want to think about getting a new RD for your parts bench. Shimano has gone to a low-normal for their mtb RDs. That means that when cable tension is released, the derailer moves to the LOWEST gear in the cluster (big cogs). Previously they worked like Road derailers, a hi-normal, release the tension, it moves to the highest gear (smallest cogs).

Now, you may ask "Why is this important to me?"....
.
..
...
Well, I'm waiting......


Ok, I'm glad you asked. This means that the shifting pattern is just opposite. If you're using brifters, sweeping the lever will move you to a HIGHER gear, and hitting the paddle moves you to a LOWER gear. This is going to be just backwards of how you are used to it working, and if you also ride a bike with a road group on it you're going to have to remember 2 different patterns depending on which bike you're on. For me that's going to be recipe for disaster on a hill. If you run barends, it won't be as bad, but the pattern will still be reversed.

The Shimano M750 is the HIGH NORMAL RD. From what I've gathered from the MTB forum the High Normal are pretty much discontinued except for the Deore model. Now they are all Low-Normal (aka "Rapid Rise") I think I'm going to head over to e-bay and grab a few of the older XT RDs while they are still plentiful.

Just my thoughts,

Steve W
Who realizes that he's been working as a tech trainer WAY too long, based on how he writes
*Edited to correct a techical boo-boo
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Old 11-03-05, 10:51 PM   #2
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Couldn't I just get a SRAM?
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Old 11-03-05, 10:59 PM   #3
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SRAM's are High normal, like a road RD, but they have a totally different pull ratios at the DR. With Smimanos, a 1 mm pull of the cable moves the derailer 2 mms (1:2 Ratio). SRAMs have a 1:1 ratio, so that 1 mm of cable pull moves the derailer 1 mm. Because of this, they won't work, at least until somebody makes a shift-tec type device to correct the pull.

Steve W
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Old 11-03-05, 11:10 PM   #4
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My tourer is the only bike equipped with bar end shifters. A low normal RD may not be a bad thing with bar end or down tube shifters as both FD and RD levers will now move in the same direction if you want to move your chain into high or low gear....
Some of the down tube old timers won't be able to double shift....

Last edited by roadfix; 11-04-05 at 01:16 AM.
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Old 11-04-05, 12:23 AM   #5
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Are you serious about this change? Or, is this some instant web myth, if-you-haven't-heard-a-rumor-by-noon-start-one?

I've ridden high normal rear deraileurs for 35 years, road and MTB. It would take the rest of my life to relearn how to shift. When I REALLY want to shift, it's to a lower gear. I'd really prefer the cable did the pulling not some spring to do the pushing.

Or, am I misunderstanding?

_I_ wish they go back to making high normal front derailleurs. That is what I grew up on. I still shift the wrong direction, from time to time on the front, pulling back up my bar end shifters when I really wanted to shift to the small ring (on a triple).

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Old 11-04-05, 12:54 AM   #6
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Quote:
Originally Posted by sakarias
Are you serious about this change? Or, is this some instant web myth, if-you-haven't-heard-a-rumor-by-noon-start-one?
Low normal/rapid rise XT & XTR RD's have been out for some time now.
These derailleurs depend on spring tension to push the chain onto the bigger cog.......how dependable is that under load in the middle of a steep climb?

Last edited by roadfix; 11-04-05 at 01:01 AM.
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Old 11-04-05, 05:21 AM   #7
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That's interesting. I haven't heard this one yet. One advantage, I suppose, is that if you are in the middle of BFE and break a RD cable, you would drop into a lower gear instead of a higer gear? It beats the crap out of trying to get someplace fully loaded and in your highest freewheel gear!

I haven't kept up with technology very well. Maybe I need to pose as an interested bicycle purchaser and go test ride a few. Might be fun!
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Old 11-04-05, 06:52 AM   #8
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Quote:
Originally Posted by sakarias
Are you serious about this change? Or, is this some instant web myth, if-you-haven't-heard-a-rumor-by-noon-start-one?

I've ridden high normal rear deraileurs for 35 years, road and MTB. It would take the rest of my life to relearn how to shift. When I REALLY want to shift, it's to a lower gear. I'd really prefer the cable did the pulling not some spring to do the pushing.

Or, am I misunderstanding?

_I_ wish they go back to making high normal front derailleurs. That is what I grew up on. I still shift the wrong direction, from time to time on the front, pulling back up my bar end shifters when I really wanted to shift to the small ring (on a triple).
Sakarias,

I'm afraid that it's true. I've been to the shimano site, the LX, XT, XTR are all rapid rise now, only the Deore is hi-normal. I also searched the MTB forums, the touted benefit is that the spring pressure will help with shifts to your lower gears, making it easier to shift while climbing.

You've got the concept right, with rapid rise, when you let off of cable tension the spring forces the RD INWARD toward wheel. In Hi-Normal (hereafter refered to as "The Correct Way" or "TCW") the spring forces the RD OUTWARD from the wheel.

I don't know how it will all shake out, like I said, I think I'm going to lay in a supply of some extra TCW Units.

Steve W.
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Old 11-05-05, 01:39 PM   #9
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I just can't see this being a problem. Ever drive in England on the wrong side of the road, with the geashift in the wrong hand. Don't remember that being a problem.

If it works better, I'm all for it. Though it sounds like a further reason to just bail into the gearhub world.
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Old 11-05-05, 02:09 PM   #10
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Quote:
Originally Posted by jharte
That's interesting. I haven't heard this one yet. One advantage, I suppose, is that if you are in the middle of BFE and break a RD cable, you would drop into a lower gear instead of a higer gear?
Not much of an advantage, because the rd moves all the way back up the cassette to the biggest cog if you break a cable. You'd still have to jurry rig something-like tie the cable off to get a nice "tween" gear-to actually be able to get somewhere.

Seems the springs would be more prone to problems, but I'm no engineer.
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Old 11-05-05, 10:52 PM   #11
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I think that Shimano will probably continue to produce high normal XT rear derailleurs even if low normal is the new standard. If they don't, well that is one more reason to hate the bastards and switch to Campy or SRAM. SRAM does have a road gruppo coming out this year...
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Old 11-06-05, 08:12 AM   #12
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I run the XTR "low normal" on my bike and LOVE IT! It shifts smoother than any other derailleur I've ever used (except my Campy carbon record), and is CHEAP to buy!

Sheldon Brown agrees with me on this - Low normal derailleurs are GREAT!
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Old 11-07-05, 10:24 AM   #13
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To slow down some of the panic,

Just because they aren't listed in the Shimano website or even in their product line doesn't mean that they won't continue to be made and available through catalog order from someone like Quality or BTI at your local bike shop.
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Old 11-07-05, 10:31 AM   #14
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The Shimano 105 and Ultegra long-armed triple rear derailleurs work fine. No reason to worry about mountain bike stuff. What's more, mountain bikes are certainly passe' now and I would expect a lot of that stuff to disappear pretty soon anyway.
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Old 11-07-05, 10:41 AM   #15
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Quote:
Originally Posted by bandregg
To slow down some of the panic,

Just because they aren't listed in the Shimano website or even in their product line doesn't mean that they won't continue to be made and available through catalog order from someone like Quality or BTI at your local bike shop.
True..... I'm still running a 7-speed on my commuter and drivetrain parts are still readily available...
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Old 11-07-05, 12:03 PM   #16
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Quote:
Originally Posted by jharte
That's interesting. I haven't heard this one yet. One advantage, I suppose, is that if you are in the middle of BFE and break a RD cable, you would drop into a lower gear instead of a higer gear? It beats the crap out of trying to get someplace fully loaded and in your highest freewheel gear!
A quick turn of the appropriate limit screw and you can put the rear derailleur on whatever cog you desire, high normal or low normal.
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Old 11-07-05, 09:29 PM   #17
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Quote:
Originally Posted by cyclintom
The Shimano 105 and Ultegra long-armed triple rear derailleurs work fine. No reason to worry about mountain bike stuff. What's more, mountain bikes are certainly passe' now and I would expect a lot of that stuff to disappear pretty soon anyway.
Shimano 105 and Ultegra rear derailleurs can only accept a 27 tooth cog while an XT can take a 34. That is why lots of people (myself included) use mountain bike rear derailleurs on touring bikes.

Although it is true that bikes are sold like any other product, and that most people are sheep and buy whatever is trendy, mountain bikes are not and will never be "passe'". That's just plain silly. If you think that is true, bring your road bike on over and lets go for a ride on some of my favorite single track. If you can keep up with me, I'll eat my knobby tires.
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Old 11-08-05, 12:59 AM   #18
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They are just trying to turn me into a RetroGrouch aren't they ?
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