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 Post subject: rapid rise
PostPosted: Mon Oct 29, 2012 7:39 pm 
retrobike rider
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Joined: Sat Feb 12, 2011 12:00 am
Posts: 456
Location: King's Lynn
i just wanted to know if anyone can tell me the advantages or diss-advarntages of using a rapid rise mech. I have never used one before. But have just obtained one. Im building an all xtr set-up and now have in my possesion an m952 normal and an m953 rapid rise. So i dont know what to use. Both are long cage. Also is setting a rapid rise up as easy as a normal mech? 8)


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PostPosted: Mon Oct 29, 2012 8:53 pm 
Old School Grand Master

Joined: Tue Oct 09, 2007 1:55 pm
Posts: 8202
Location: New Forest, UK
All here...
http://www.retrobike.co.uk/forum/viewto ... rapid+rise


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PostPosted: Mon Oct 29, 2012 9:28 pm 
Old School Grand Master
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Joined: Sun Aug 21, 2011 11:57 pm
Posts: 4074
Location: Antwerp, Belgium
I have put a rapid rise mech on a normal bike once. The owner got used to the inverted shifting pattern pretty quickly.

However at some point his 6yo son got hold of the right sized Allen key, undid the bolt that holds the cable ... and then lost the key and the bolt. I decided to ride it to my place so I could work on it properly.
2 miles in city traffic, with a 22-34 and a 32-34 to choose from = no more rapid rise for me.


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PostPosted: Tue Oct 30, 2012 1:35 am 
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Joined: Wed Dec 14, 2011 2:27 am
Posts: 454
Location: Brasov, Romania
I have about three XT Rapid Rise derailleurs, but only one is mounted on a bike, my Jekyll 1000 SL that I ride quite a lot. You get pretty easily used to it and I quite like it, but I guess it's more tricky to set up, I can't tell why. I am still after an XTR one with that pulley. M951 it must be. My friend who is a multiple Dual and 4X National Champ over here used it for racing. He started in a low gear for the sprint and then shifted 3 to 5 gears at once, depending on the lever, to get to his cruising speed. This tactic proved to be quite succesful. I buy my Rapid Rise derailleurs cheaply, because people don't quite understand them. Oh, and don't get me started on Dual Control! :))

Mx


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PostPosted: Tue Oct 30, 2012 9:07 am 
Retro Guru

Joined: Sat Aug 15, 2009 12:41 pm
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Location: Chiltern Hills
Although RR did take a bit of getting used to, I now have them on all five of my bikes (including the road bike 8) ) personally I like the way you can drop quickly into lower gears, don't see how they are any different to set up than conventional mechs.


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PostPosted: Tue Oct 30, 2012 9:27 am 
Old School Grand Master

Joined: Tue Oct 09, 2007 1:55 pm
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Location: New Forest, UK
Mine started getting slightly tetchy with age and used to ghost shift. Remember all that keeps it in gear is that spring. On a conventional mech it is the chain tension.

Swapping to a conventional mech stopped the ghost shifts.


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PostPosted: Tue Oct 30, 2012 7:05 pm 
Retro Guru

Joined: Tue Sep 01, 2009 12:28 pm
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Location: Almeria, Spain
I might be in a minority of 1 but I like them when used with dual control. The main advantage for me is that you can change down whilst braking hard and be ready for what's to come. I'm only sorry Sram don't make them as well. :lol:


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PostPosted: Tue Oct 30, 2012 11:52 pm 
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Joined: Sat Oct 03, 2009 2:37 pm
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Location: UK Southwest
hamster wrote:
Mine started getting slightly tetchy with age and used to ghost shift. Remember all that keeps it in gear is that spring. On a conventional mech it is the chain tension.

Swapping to a conventional mech stopped the ghost shifts.


All mechs can ghost shift if poorly setup or if the cable is in poor condition. I don't see how rapid rise is any more prone than a conventional mech. It's the spring pulling on the cable that defines the gear the mech is lined up with in both cases. If the cables are old and gummed up then the spring isn't strong enough to pull all the cable that is released by the shifter. Your thumb however, when pulling cable back in, is strong enough to pull all the cable back, plus the shifter won't click to the next index until all the cable is back in anyway. Thats why some times you have to go down two and back up one. Or in the case of rapid rise up two and back down one.

Rapid rise is kinder on the chain when shifting into lower gears (gears with more teeth) underload, which people tend to do when riding up hills. With a conventional mech you are pulling cable back in so you apply pressure to the shifter until it clicks into the next index and the mech HAS to move to the next gear which puts alot of side load on the chain (eventually pulling the outer links off the pins and causing it to snap), it shifts and makes bad noises whilst doing so.

With rapid rise however you are releasing cable as you shift into a lower gear meaing the mech won't move all the way across to the next gear as it is only the fairly weak spring pulling it over, not your thumb and the cable. The side load on the chain therefore isn't nearly as much, the shift occurs when the ramps come round and its all alot smoother and nicer. Shifting into higher gears under full load on the other hand is not as smooth with rapid rise but how often do we do that. If we are shifting into a higher gear then it usually means we can afford to back off the load when doing so.

In my opinion rapid rise actually makes more sense than conventional and is probably the way it should always have been.


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 Post subject:
PostPosted: Wed Oct 31, 2012 9:16 am 
Old School Grand Master

Joined: Tue Oct 09, 2007 1:55 pm
Posts: 8202
Location: New Forest, UK
I agree on the setup issue. However what happened was that I swapped mech only, so the cabling was entirely unchanged.
The ghost shifting happened when gears were running totally quietly so minimal misalignment, however the thing would then up shift up under heavy load as the spring was too weak to hold a lower gear. This happened when in lower gears due to the slightly diagonal pull on the mech from the chain, for example on the largest sprocket and middle chainring. My setup is 7 speed with bar-ends on the front.

Pay your money and take your pick. Not for riding a loaded tourer, for me anyway.


Last edited by hamster on Wed Oct 31, 2012 8:43 pm, edited 1 time in total.

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 Post subject:
PostPosted: Wed Oct 31, 2012 1:58 pm 
Retro Guru
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Joined: Sat Oct 03, 2009 2:37 pm
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Location: UK Southwest
hamster wrote:
I agree on the setup issue. However what happened was that I swapped mech only, so the cabling was entirely unchanged.
The ghost shifting happened when gears were running totally quietly so minimal misalignment, however the thing would then up shift up under heavy load as the spring was too weak to hold a higher gear. This happened when in lower gears due to the slightly diagonal pull on the mech from the chain, for example on the largest sprocket and middle chainring. My setup is 7 speed with bar-ends on the front.

Pay your money and take your pick. Not for riding a loaded tourer, for me anyway.


Ah okay I hadn't considered the diagonal pull from the chain. Makes sense now as the chain is at quite an angle when in the higher gears even in the granny ring and especially when running a 50mm chainline like the modern stuff does.


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