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Shimano XT gear system

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Old 10-15-06, 04:46 AM
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JackDaw
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Shimano XT gear system

i have just purchased a shimano XT gear change system for my handle bars. no problems with installation. i hgave found though that when i change to go higher on the rear sprocket the gear goes lower. it says on the handlebar mechanism though that the gear has gone higher. i.e i can be in very high on the handle bar but it is 1st gear on the rear sprocket.

is this a known problem?? if so how can i fix this?? have i installed it wrong??
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Old 10-15-06, 06:31 AM
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Shimano has high normal (traditional) and low normal (rapid rise) mountain bike gear systems. The only difference so far as shifters are concerned is how the numbers are located on the gear indicator. The only way to really fix it would be to buy either a new shifter or a new derailleur so they match. If it was my bike I'd just live with it the way that it is.
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Old 10-15-06, 06:39 AM
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RG is correct that you probably have one of the new low normal or, in Shimano-speak "Rapid Rise", rear derailleurs so it works in reverse of the former high-normal type. Unless you are willing to return it for the older type, I'd do what RG suggests and ignore the numbers on the shifter.
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Old 10-15-06, 12:10 PM
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I personally don't care for shift indicators, therefore it it were me I'd simply cover the indicator window with electircal tape, or remove the indicators all together.
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Old 10-15-06, 12:25 PM
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Yes. The issue has to do with the derailleur travel direction. The bigger issue you should be thinking about is whether or not you want lo-normal/Rapid-Rise. I personally don't like it.

Rapid-Rise sucks in many ways, IMHO. For the non-XC racer who hasn't had a chance to go over and preview every trail/course, the Rapid-Rise introduces many annoyances beyond just having to rethink which direction to shift. The first is that you have to click your way in the downshift direction one gear at a time. This can really make or break clearing an obstacle or setting up a line or maintaining your speed/cadence when climbing a hill that's surprised you.

Another thing is the gate-lag which means that you have to rotate through a certain arc before the shift actually happens regardless of when you initiated the shift from the shifters... and this happens on the downshift. Also, this gate-lag is more apparent when you're moving slowly. That is the rate at which you can shift is dependent on how fast the rear wheel is moving.

Additionally, you can compound the problem when trying to force a shift. You can force the shift with traditional derailleurs no-problem but if you do it with Rapid-Rise and miss the gate then you succumb to the lag. Shimano as well as other manufacturers design their cogs with shift-assisting gate ramps to create smoother shifting. This means that the chain will shift optimally and more smoothly at certain points on the cog's rotation.

When you downshift (move to a larger cog) on a traditional high-normal rear derailleur, you can force the shift at any point regardless of where the gate ramps are and thus can downshift faster than what would be optimal from a smoothness standpoint. You can trade off smooth shifting for speed in the downshift direction. However in the upshift direction (moving to smaller cogs), you will be at the mercy of the shift gates.

In a low-normal rear derailleur such as the RD-M960, the opposite happens. You can force the shift and override the gates in the upshift direction but when you downshift, you are releasing tension on the rear derailleur so it moves at its own preset pace. Additionally, because downshifting is moving upwards on the cogstack, you will see more of a delay because you have to cause the chain to climb up the cog as opposed to simply falling down as in the upshift direction. This is just one of the reasons why I dislike Rapid-Rise... it's actually not all that rapid.

Also, another problem with Rapid-Rise is that it is more prone to mis-shifting in the downshift direction when the cables or mechanism gets gunked up. Basically, Rapid-Rise favours upshifting but does so by sacrificing downshift performance. And as most MTBers can testify, it's usually more critical to hit the downshift than the upshift unless you're on a well-known trail in an XC race.
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Old 10-15-06, 02:29 PM
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Originally Posted by JackDaw
i have just purchased a shimano XT gear change system for my handle bars. no problems with installation. i hgave found though that when i change to go higher on the rear sprocket the gear goes lower. it says on the handlebar mechanism though that the gear has gone higher. i.e i can be in very high on the handle bar but it is 1st gear on the rear sprocket.

is this a known problem?? if so how can i fix this?? have i installed it wrong??
Just to clarify things.

What are you calling 1st gear on the rear sprocket?
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Old 10-15-06, 02:30 PM
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Very good description of the mechanism and problems with "Rapid Rise". I've always thought that relying on the derailleur spring to force the downshifts wasn't a good idea. As you mentioned, the shifts you are often in a REAL HURRY for are downshifts and usually more than one.

BTW, breaking your posting into a few paragraphs would make it a bit easier to read. The info is very good but tends to get lost in the mass of words.
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Old 10-15-06, 02:43 PM
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Originally Posted by HillRider
BTW, breaking your posting into a few paragraphs would make it a bit easier to read. The info is very good but tends to get lost in the mass of words.
Yeah. Sorry. I was in a hurry. I'll fix it now.
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Old 08-21-08, 09:10 AM
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Originally Posted by khuon View Post
Rapid-Rise sucks in many ways, IMHO. For the non-XC racer who hasn't had a chance to go over and preview every trail/course, the Rapid-Rise introduces many annoyances beyond just having to rethink which direction to shift. The first is that you have to click your way in the downshift direction one gear at a time.
I'm new to some of this bike stuff and I thought I knew what rapid rise was but after reading your comment (above) I'm now not so sure. I thought rapid rise was a mechanism such that with one click of the shifter it would release all the tension on the cable and return the derailleur to it's normal (low for a low normal rear derailleur) position. You indicate that you have to down shift one gear at a time. Can you help clear this up for me?

Thanks,
Nick
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Old 08-21-08, 09:27 AM
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Originally Posted by nickdu View Post
I'm new to some of this bike stuff and I thought I knew what rapid rise was but after reading your comment (above) I'm now not so sure. I thought rapid rise was a mechanism such that with one click of the shifter it would release all the tension on the cable and return the derailleur to it's normal (low for a low normal rear derailleur) position. You indicate that you have to down shift one gear at a time. Can you help clear this up for me?

Thanks,
Nick
Shimano always "releases" one gear at a time. With the old "high normal" system, you could only upshift (go to a smaller cog) one cog at a time and had to click multiple times to get additional smaller cogs. You could "downshift" (go to a bigger cog) as many as three or four at a time with a full sweep of the lever.

With the "Rapid Rise" system, the reverse is true. You can only downshift one cog at a time and have to click the lever once for each cog you want. Multiple upshifts can be made by sweeping the lever further.
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Old 08-21-08, 09:46 AM
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I do not believe that Shimano makes a matching rapid rise shifter on which the gear numbers are reversed.

If 1 is high on one style rear derailleur, then its low when the other derailleur is installed.

No other changes necessary except inside your head.
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Old 08-21-08, 03:12 PM
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Originally Posted by HillRider View Post
Shimano always "releases" one gear at a time. With the old "high normal" system, you could only upshift (go to a smaller cog) one cog at a time and had to click multiple times to get additional smaller cogs. You could "downshift" (go to a bigger cog) as many as three or four at a time with a full sweep of the lever.

With the "Rapid Rise" system, the reverse is true. You can only downshift one cog at a time and have to click the lever once for each cog you want. Multiple upshifts can be made by sweeping the lever further.
Initially I was thinking I wanted rapid rise because I thought I could go all the way to the lowest gear (biggest cog) with one click. Now that you've explained it for me (thanks) it sounds like I want a "top normal" rear derailleur.

Nick
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