Mountain Biking - Should a mtn bike be able to shift multiple gears at once?

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legalize
04-30-06, 09:05 PM
I'm going to be testing a bike and I need to know if a bike can handle that.

Also - Should it be able to handle it when you put force on the peddles and shift at the same time?

Thanks


Ronsonic
04-30-06, 09:17 PM
Some only go one click at a time, either in one direction or both.

You should be able to shift front and back derailleurs at once.

Whether it should be able to handle it is far different from should you do it to any bike, especially if it isn't your own.

The pedals should be moving when you shift and lightly loaded. Dropping to the granny ring under load is just sorta asking for a chainsuck episode.

Be nice to bikes, they'll treat you better for it.

Ron

legalize
04-30-06, 09:23 PM
Thanks I've always wondered these things because usually most bikes can't handle it so thats good to know


WannaGetGood
04-30-06, 09:23 PM
Mine can go down by 2 if I want it to. I just need to press harder.

khuon
04-30-06, 09:32 PM
Typically it depends on the shifters. Here's a basic breakdown...


Friction Thumbshifter - multiple shifts in both directions are possible but you have to "know how to shift" meaning you need to feel yourself into the gears
Indexed Thumbshifter - multiple shifts in both directions are possible and each gear will click into place
GripShifters/Twistshifters - same as Indexed Thumbshifters
1st and 2nd Generation RapidFire Shifter and Dual-Control - multiple shifts (usually a limit of 3) in the direction of pull are possible (upshifting chainrings or downshifting cassette for high-normal; upshifting chainrings or upshifting cassette for low-normal) but only a single shift is possible in the cable-release direction (downshifting chainrings or upshifting cassette for high-normal; downshifting chainrings or downshifting cassette for low-normal)
3rd Generation RapidFire Shifter (Dual-Release) - multiple shifts in either direction are possible (usually a limit of three in the pull direction and two in the release direction - shifting direction as per hi/lo-normal biasing)


And as others have said, double-shifting (shifting front and rear simultaneously) is supported but not often recommended... especially under heavy offroad jouncing.

gmoneyhobbit
04-30-06, 11:49 PM
Typically it depends on the shifters. Here's a basic breakdown...


Friction Thumbshifter - multiple shifts in both directions are possible but you have to "know how to shift" meaning you need to feel yourself into the gears
Indexed Thumbshifter - multiple shifts in both directions are possible and each gear will click into place
GripShifters/Twistshifters - same as Indexed Thumbshifters
1st and 2nd Generation RapidFire Shifter and Dual-Control - multiple shifts (usually a limit of 3) in the direction of pull are possible (upshifting chainrings or downshifting cassette for high-normal; upshifting chainrings or upshifting cassette for low-normal) but only a single shift is possible in the cable-release direction (downshifting chainrings or upshifting cassette for high-normal; downshifting chainrings or downshifting cassette for low-normal)
3rd Generation RapidFire Shifter (Dual-Release) - multiple shifts in either direction are possible (usually a limit of three in the pull direction and two in the release direction - shifting direction as per hi/lo-normal biasing)


And as others have said, double-shifting (shifting front and rear simultaneously) is supported but not often recommended... especially under heavy offroad jouncing.


actually 2nd gen rapid fire shifters allow you to pull 4 gears at a time

jim-bob
04-30-06, 11:50 PM
I can't stand trigger shifters. I'm slowly warming up to indexing, though.

khuon
05-01-06, 12:26 AM
actually 2nd gen rapid fire shifters allow you to pull 4 gears at a time

You're right. However, it does depend. Some versions of RapidFires will allow for different levels of pull per stroke. Regarding the right-hand shifters, my old DeoreDX (RapidFire Gen-1, push-push) and DeoreXT (RapidFire+ Gen-2, push/pull triggers) 7-speed shifters pulled enough for only three rear cogs. My 8-speed DeoreXT and 9-speed DeoreLX, DeoreXT and XTR RapidFire+ 2nd. generation shifters will pull across four. I believe 3rd generations also will do four instead of the three I previously mentioned.

khuon
05-01-06, 12:29 AM
I can't stand trigger shifters. I'm slowly warming up to indexing, though.

I think it's interesting to note that many people criticised Shimano's 1st gen RFs for being push-push which is why they came out with triggers on the RF+. Now it seems everyone's excited about having a pushable extension for the release. Shimano's new Dual-Release and Dual-Control levers as well as SRAM's trigger shifters allow you to push for release.

sphynx_000
05-01-06, 12:33 AM
what do you mean push to release, same as push-push?

release tension, and switch a gear?

willtsmith_nwi
05-01-06, 12:37 AM
And as others have said, double-shifting (shifting front and rear simultaneously) is supported but not often recommended... especially under heavy offroad jouncing.

I do it all the time. For me it's critical to switching rings without changing the gearing ratio. On Gripshift it is easy, just do three clicks simultaneously on both shifters in the same direction. That is, either throttle towards yourself with both hands or throttle away from yourself with both hands ... 3 clicks. Depending on your cassette/ring setup, your mileage may vary.

jim-bob
05-01-06, 12:50 AM
I think it's interesting to note that many people criticised Shimano's 1st gen RFs for being push-push which is why they came out with triggers on the RF+. Now it seems everyone's excited about having a pushable extension for the release. Shimano's new Dual-Release and Dual-Control levers as well as SRAM's trigger shifters allow you to push for release.

I still haven't used a finer shifter than the first-gen XC Pro thumbshifters. Mmmm, retrofriction.

khuon
05-01-06, 02:02 AM
I do it all the time.

I do it often too but there is a greater risk of throwing a chain when doing so.

khuon
05-01-06, 02:06 AM
what do you mean push to release, same as push-push?

release tension, and switch a gear?

Yes. Push to release means you push on a button/lever in order to release the cable tension. Older first generation RapidFire shifters had a release button positioned over the pull-lever. You pushed on the cable-pull lever to pull the cable and you pushed the button to release the tension. Shimano then switched to using a trigger which you pulled to released the tension. The latest generation of RapidFires allow you to do either. You can push or pull on the release lever. And it has a double-throw meaning you can push or pull further to release enough cable to shift up to two cogs at a time.

legalize
05-01-06, 07:32 AM
wow the world of gears is quite complicated

khuon
05-01-06, 09:12 AM
I still haven't used a finer shifter than the first-gen XC Pro thumbshifters. Mmmm, retrofriction.

The XC Pro topmounts were indeed great shifters. I liked them better than the DeoreII/DeoreXT topmounts as quality goes. PowerRatchet (aka RetroFriction) was wonderful but unfortunately SunTour's introduction of indexed shifting ala Accushift was far less than spectacular.

concernicus
05-01-06, 11:51 AM
i can move down three gears at one time with my deore triggers/xt rd

henrymchugh
05-01-06, 05:07 PM
Why would you want to shift the front gear and rear gears at once? You would kill the transmission.