Clutched rear derailleur 2x

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jfranci3
Posts: 1572
Joined: Tue Jul 26, 2016 5:21 pm

by jfranci3

My Trek Crockett w/ SRAM Force 10 bits and 50/34 11-28 gearing has been acting up on the small ring. The chain was flopping about and falling off the jockey wheels at times. Did a full maintenance on it and discovered a hanger screw missing. I corrected that, but I'm pretty sure the jockey wheels are done anyway and the rear derailleur may be bent. I ride 90% with my 25c wheelset and 10% on hardpack/aggregate.

Any advantage to getting a clutched rear derailleur? I'm probably going with a medium 26-32 cog size. I think it'd be nice to have an 1x upgrade path.

commendatore
Posts: 273
Joined: Mon Dec 30, 2013 1:51 am
Location: North Carolina

by commendatore

The Force1 and Rival1 rear mechs are not designed to be used with a double. I'm not sure if Sram makes a road mech that will work but maybe the old x9 is a possibility?

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jeanjacques
Posts: 349
Joined: Thu Apr 14, 2016 11:01 am
Location: France

by jeanjacques

Every Sram 10s MTB rear derailleur will work with 10 and 11 speeds road shifters.

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jcrr
Posts: 246
Joined: Wed Nov 30, 2011 4:36 am
Location: PNW USA

by jcrr

+1 what commendatore said on incompatibility of road clutch-RDs and 2x. So if that's what you got, that would explain the issue.

My suggestion is you replace with a medium cage road RD if you want to go to 32 on the back. I have raced CX with a Rival Wi-Fli and 2x, and have had zero issues in all conditions (dry <-> mudfest). You could also go with a mtb RD and insert an in-line barrel adjuster for ease of tweaking.

Also, check the hanger isn't bent.

JC
"If it ain't broken, it could be lighter"

motorapido
Posts: 334
Joined: Fri Jul 30, 2010 7:08 pm

by motorapido

It will work if you use a J-tek shiftmate, this uses a stepped pulley to multiply the cable movement up or down as required for different shifter and mech combinations.

http://www.jtekengineering.com/resource ... atibility/

Same principal as the problemsolvers travel agents used to run Vee brakes with drop brake levers,

jfranci3
Posts: 1572
Joined: Tue Jul 26, 2016 5:21 pm

by jfranci3

No. I have a regular 10sp Road RD. I'll pick up a new wifli RD and hanger. I took the bike for a ride after getting the bolt fixed and everything adjusted and there's still something off. Lot's of slack in the small ring, mid gears.

Marin
Posts: 4035
Joined: Wed Jan 22, 2014 11:48 am
Location: Vienna Austria

by Marin

A clutched derailleur will help the chain stay on the chainrings for super-rough rides.

I'm riding road 1x with non-clutched derailleurs without problems, and I'm running my drop-bar MTB with a non-clutched derailleur as well. The narrow-wide chainring is enough to keep the chain on.

The issues you're seeing don't sound like they could be remedied with a clutch derailleur.

How long is your chain?

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wheelsONfire
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Location: NorthEU

by wheelsONfire

I wouldn't mind a clutch RD for 2*11.
I find the issue is shifting down from big to small, chain likes to squeeze inbetween the small and BB.
I see it jumps at approx 3 o'clock. Running a 36T prevents this, but going smaller makes it worse.
No matter if i keep a short chain, chaincatcher does not prevent this.
It should have to be a chaincatcher that is like a 180 degree circle preventing the chain from jumping.
I partly suspect it's the chainline that would have to be more outboard.
I have seen there are some suggestions that it actually is the chainline that is the problem (especially the small).
Some say the spacing of the cassette is same as a road bike (not 12*142 TA).
But some also suggest the chainline actually would need to be 45.5mm or more.
I have tried to find 2*11 offset chainrings, but i haven't.
I wonder if running a larger cassette also is partly to blame?

MTB's with 12*142 has an offset chainline compared to road bikes.
I've currently been told by Rotor to wait until Eurobike.
Perhaps they have something cooking... i surely hope so.

This is a problem i have been trying to find a fix for. But none so far.
Adjusting does not help me one bit.
Bikes:

Ax Lightness Vial EVO Race (2019.01.03)
Open *UP* (2016.04.14)
Paduano Racing Fidia (kind of shelved)


Ex bike; Vial EVO D, Vial EVO Ultra, Scott Foil, Paduano ti bike.

motorapido
Posts: 334
Joined: Fri Jul 30, 2010 7:08 pm

by motorapido

Wheelsonfire, the spacing of and position of the cassette on an mtb hub, be it 135mm or 142mm is the same relative to the rear mech's mounting face, the extra length of the axle is only the interface with the dropouts.

I would agree that Chain-line is potentially the cause of your problems, a road double midpoint is typically 45 , whereas an mtb is normally about 47.5,
one way to achieve an offset would be to machine up a ring the width of your cranks chainring mounting tabs with 2 sets of holes in it, assuming there is enough clearance with the crank arm, then bolting this to the outside of the crank arm with the rings either side it will offset them.

You could also try an mtb 2X chain-set, as this would have the bigger offset but you might struggle to get larger than a 44t outer chainring.

i wouldn't have thought that the cassette size is much of an influence as the point that the chain leaves contact with the cassette won't vary much relative to the axle centreline.

I would suggest that an MTB 11speed clutch rear mech with the short cage of a Zee SS mech would be the best solution with a j-tek shift-mate.

jfranci3
Posts: 1572
Joined: Tue Jul 26, 2016 5:21 pm

by jfranci3

While waiting for my new derailleur to come in, i went for a ride on the old 'n busted one.

https://goo.gl/photos/pXy85wYeT2E3jLQv6

Earlier in the ride I noticed my derailleur arm had cracked at the lower jockey wheel interior side. I was already going, it was working ok, it wasn't a long ride, and figure the failure would just be the chain dropping. 3 miles later, I feel and hear something. Luckily, I had planned to lock the rear brake on any funny feelings. I got it stopped before it locked my wheel, started taking out spokes, or ripping out cable.
Looks like it locked the chain in the arm and ripped everything off. The derailleur hangar did it's job and failed before destroying the frame.

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silvalis
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Location: Aus

by silvalis

What did you order?

If I were you, I'd have grabbed a sram gx 2x10 clutched RD. Cheap and reliable.
Chasse patate

jfranci3
Posts: 1572
Joined: Tue Jul 26, 2016 5:21 pm

by jfranci3

Just a 10sp Rival medium cage unit. The Force unit is $50 more, 10g lighter, and didn't have an extra features. The 11sp Rival unit looked purposefully ugly.

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wheelsONfire
Posts: 6283
Joined: Mon Jul 07, 2014 8:15 am
Location: NorthEU

by wheelsONfire

I can't fit a mtb crankset on my UP.
I have asked the guys at Open, but it's a no-go...

I have thought about making something to fiddle with the offset of chainrings.
But i'll probably wait and see what Rotors comes up with at Eurobike.

A pity Shimano didn't make the new Ultegra in a versions (RD especially) for CX/gravel micro compact chainrings.
Most FD handgers doesn't allow the FD to be moved close enough to the chainrings.
I think i measured mine to +7mm using 44T big chainring.
However, i just did an easy change to make this work.
So i will see if this works better.
Today i heard the typical throw sound when the chain jumps, going from big to small chainring.
But it didn't jump.

A clutch RD had been very interesting to try.
I will never switch to 1*11. I use both the small and the large chainrings too much.
I like using a 44T front rather than 46T.
Higher cadence less torque, i think it works better.
I doubt i would use anything lower than 32T as inner.
Bikes:

Ax Lightness Vial EVO Race (2019.01.03)
Open *UP* (2016.04.14)
Paduano Racing Fidia (kind of shelved)


Ex bike; Vial EVO D, Vial EVO Ultra, Scott Foil, Paduano ti bike.

jfranci3
Posts: 1572
Joined: Tue Jul 26, 2016 5:21 pm

by jfranci3

If you're looking for a wider chainline, probably the easiest way to widen would be with some shims http://wheelsmfg.com/crank-spindle-spacers.html

by Weenie


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motorapido
Posts: 334
Joined: Fri Jul 30, 2010 7:08 pm

by motorapido

WheelsONfire, if you want to stick with a 2x10 setup then go for a Shimano Zee SS rear mech, its 10 speed short cage and has a clutch, run it with a j-tek shiftmate 6 and it should be what you want.
Also for the front mech have you considered a cyclocross specific front mech such as the Shimano CX70 ? it would match your chainring better and can mount lower.
Am curious why Open UP reckon an MTB double wouldn't work, the Qfactor and crank arms would sit wider, and a compatible Bottom Bracket would exist. I run 44 29 rings on my BMC FS01 which would give you a great range

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