Rapid Rise Question

[Tallpaul]

Do rapid rise rear mechs work with 'ordinary' shifters? Anyone got a link that explains how the rapid rise mechanism actually operates?

Ta

 

[fuzzywig]

No... the stoopid things work backwards

 

[Crayons]

Interesting that Tallpaul should ask the very same question I've been wondering about (I've got an old rapidrise XTR sat in a box I'm thinking of putting to use). I'd assumed that that any shifter would work, just in the opposite way – so you'd push the big thumb bit to come down he block and click the little release thingy to go back up again.

:?

 

[one-eyed_jim]

In a conventional derailleur the spring passes across one diagonal of the parallelogram and the cable passes across the other. Pulling the cable extends the derailleur, while the spring tries to retract it. In a Rapid Rise derailleur the spring and cable are swapped, so the spring extends the derailleur while the cable retracts it.

Shifters are the same, but they move the derailleur the opposite way.

 

[Tallpaul]

So i could operate a rapid rise mech with a thumbie, just they would index in the reverse order?

 

[one-eyed_jim]

So i could operate a rapid rise mech with a thumbie, just they would index in the reverse order?

Yep.

 

[orange71]

what are the actual real-world benefits of this?

 

[cchris2lou]

use less force on the spring to go on larger sprocket , so really a rapid rise rear mech should last longer , and shifting smoother .

 

[South Bound]

Might be heresy, but I like my rapid rise (but then I have only ever had thumbies before now, so I don't know any different on the shifter front!)

 

[one-eyed_jim]

what are the actual real-world benefits of this?

To be honest I'm not sure there really are any - at least, any that are important.

Shimano's Hyperglide sprockets have ramps and gates that are computer designed so that during a shift to a larger sprocket, the chain can engage two sprockets at once. With a normal, non-RR derailleur, you can force the shift at a point that doesn't correspond to the Hyperglide gates. That can have advantages, but means that the shifts won't be as smooth as they should be, and puts more strain on the system. With a RR mech, you click the shifter and let the gates and derailleur spring take care of the shift.

I've heard a rumour that the first XTR titanium cassette sprockets had a tendency to bend under forced shifts, and that RR was a solution to this. I've no idea how true that might be - I'm too tight to buy titanium cassettes.

Another effect is that left and right RF+ shifters now work the same way - push for harder, click for easier. Apparently some beginners find that more intuitive - can't say I ever had a problem.

For me the nice thing is that when you combine them with Campag Ergo levers, the downshift is on the thumb button, which is a more natural motion when braking or honking on the hoods. I don't suppose Shimano's designers had that in mind.