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-   -   Dropped too often. (http://www.bikeforums.net/fifty-plus-50/669366-dropped-too-often.html)

maddmaxx 08-06-10 03:30 PM

Dropped too often.
 
I've dropped my chain 3 times in the last week. My fault, I've been trying to get by with a left over triple derailleur on a compact double mountain crank (24/36). I finally bit the bullet and ordered a new top swing Shimano SLX compact front derailleur.

I'm still a twist shifter who is in the habit of grabbing 3 or 4 gears in the back at the same time I'm changing the front ring. The old bottom swing (sitting just above a bottle bracket screw) was always just a bit high on the chain rings and all of those bumps and compromises on the inner face of the cage simply didn't maintain control of the chain in all circumstances.

I know we've beaten the compact question to death on road bikes but is anyone else using a compact mountain double setup (still 9sp, not the new sell your house stuff).

BluesDawg 08-06-10 03:40 PM

Not yet, but thinking about going that route on my Stumpy one of these days. I never use the big ring on my MTB. What crank are you using?

Where are the pictures? :rolleyes:

Bikewer 08-06-10 03:58 PM

So, is the chain coming off the crank, I gather? Which way? If you're loosing it off the big ring, then first thing is to check the limit screws for the DR. If the little ring, likewise, except that you can also get good old mountain-biker's "chain suck" from any number of things, from insufficient tension on the chain (from the rear DR springs) to having the chain be a bit too long to just being all crudded up and and adhering to the chainring.
Sounds like your shifting practices might be a bit suspect... On my old police patrol bike (a Trek MTB) I got chain -suck rather often till I started shifting onto the little ring only slowly and deliberately.

maddmaxx 08-06-10 06:52 PM

Truvativ stylo 24/36/bash. (Try Pricepoint BD) SRAM X9 components all around (new this year as as the last bike sale departed with my old ones) SRAM chain sized for 1 extra link on the 36 ring 34 cassette. The chain is dropping off the inner ring during down shifts as it falls through the granny notch on the incorrect triple derailleur that is set slightly too high because of the aformentioned bottle bracket mount. I'm sure that the SRX FD-M665 double will solve the problem as it will mount below the bottle bracket and the double variety inner cage plate will confine the chain. I may even be able to put my chain keeper back on for extra insurance.

Once that's done I'll get back the normal 2 hands full of twist grip shifting. It's a very nice feature to have when you ride into something that bogs you down.

maddmaxx 08-06-10 06:55 PM

Quote:

Originally Posted by Bikewer (Post 11245805)
So, is the chain coming off the crank, I gather? Which way? If you're loosing it off the big ring, then first thing is to check the limit screws for the DR. If the little ring, likewise, except that you can also get good old mountain-biker's "chain suck" from any number of things, from insufficient tension on the chain (from the rear DR springs) to having the chain be a bit too long to just being all crudded up and and adhering to the chainring.
Sounds like your shifting practices might be a bit suspect... On my old police patrol bike (a Trek MTB) I got chain -suck rather often till I started shifting onto the little ring only slowly and deliberately.


I believe that once the system is set up correctly you should be able to bang through the gears at will. That's one of the reasons that I prefer the compact double on both MTB and Road bike...........bulletproof shifting. I just cheaped out and used stuff from under the work bench to create a bad system.

HAMMER MAN 08-07-10 11:52 AM

try this, well worth the $39.00, easy to install

http://www.acecosportgroup.com

maddmaxx 08-25-10 09:07 AM

Just as a follow up for Bluesdawg and others, the mountain double front derailleur solved the problem completely. It is necessary to adjust the height so that the cage just barely clears the outer bash ring while shifting up to the mid (high on the mountain double crankset) ring. At that point, the inner and outer cages can be adjusted so close to the extreme positions (inner/inner and outer/outer) that the derailleur acts as a chain keeper.

This restores the ability to use what might be my favorite feature of twist shifters, the ability to drop from the high to low chain ring while simultaneously changing up 3 or 4 gears on the cassette. All done in one pedal rotation. This is the dreaded 0 change shift while moving from the inner front ring to the outer and vice versa. Traditional shifters may choose not to, or be unable to make this change in the same quick motion.

NOS88 08-25-10 10:30 AM

Quote:

Originally Posted by HAMMER MAN (Post 11249547)
try this, well worth the $39.00, easy to install

http://www.acecosportgroup.com

+1 This thing really works, but I don't remember paying that much for mine at my LBS.

lhbernhardt 08-25-10 11:32 AM

Quote:

Originally Posted by maddmaxx (Post 11350881)
This restores the ability to use what might be my favorite feature of twist shifters, the ability to drop from the high to low chain ring while simultaneously changing up 3 or 4 gears on the cassette. All done in one pedal rotation. This is the dreaded 0 change shift while moving from the inner front ring to the outer and vice versa. Traditional shifters may choose not to, or be unable to make this change in the same quick motion.

This should not be a problem at all with Campag Ergopower shifters. Also, back in the old days, when the shift levers were on the downtube, I used to use my right thumb to push the left lever forward while using my right index and middle fingers to pull the right lever back (or forward), shifting both derailleurs simultaneously just before climbs. Harder to do this the other way (left lever back, right lever forward) - I'd have to do this in sequence, but I would usually shift the left lever with the right thumb. The old Simplex/Mavic retrofriction levers required such little force that this was easy.

Luis

maddmaxx 08-25-10 11:50 AM

Quote:

Originally Posted by HAMMER MAN (Post 11249547)
try this, well worth the $39.00, easy to install

http://www.acecosportgroup.com

I like chain keepers..........they are like insurance. Even if something goes wrong, it's not going to go wrong. Normally I use an N-Gear Jump Stop, but for some reasons (including the locations of bottle bracket screw mounts), it simply will not fit on this frame without interfering with the derailleur cage or the frame. People using a triple absolutely should look into some sort of chain keeper that catches the chain and deflects it back on to the granny before it falls off. Even if your derailleur system is working perfectly, eventually, you will drop a chain and scratch the paint.


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