[frorider]

When I built up my Norco Truax last year with my existing build kit (steel SLX cranks, 22/36 rings, SLX 2X front derailleur) with a Heim roller guide and a bashring, occasionally I'd get a drop to the granny gear on rough terrain...or some chain issues when momentarily back-pedaling. So this year I decided to get the MRP 2X taco guide (see pic). I've had mixed results with it. One issue is that MRP decided to make the plastic assembly that encases the pulleys with super soft and flexible plastic...so on really fast rough sections, the chain manages to squirm itself out of the guide entirely (the pulley is slammed all the way forward on the mount).

The front der mount on the Norco is directly on the chainstay, which is a generally good idea for a long-travel bike, but it also means it's impossible for me to mount the front derailleur any lower than in the pic. This means that the top of the metal cage (which helps reduce vertical motion of the chain) is way far above the ring. I fabricated a black plastic shim to help fill that gap (see pic), which helped but didn't solve the issue. I can see a couple of options:

1. Throw the MRP guide into the trash, and buy an E13 double shift guide...but are those any stiffer/better than MRP?
2. Buy a 38T ring (e.g. blackspire super pro), which would let me avoid the smallest rear cogs...that seems to keep the chain tension high enough to help. Side benefit is that a larger diameter chainring would reduce the distance to the top of the front der cage
3. Switch the drivetrain to a 2X10, run a clutch XT rear derailleur....if this were my main bike I could justify the $$ but I'm also building up an XTR 2X10 Bronson, and would like to get more use out of this current drivetrain
4. ??

 

[WestCoastHucker]

4. profit...

 

[jonKranked]

Front deraillers are for xc bikes. Throw the whole thing in the trash.

 

[IH8Rice]

i guess its the FD mounting issue since i havent had a problem like you describe with almost the same setup (different cranks)

 

[frorider]

Would like to ditch the front der, but I'm lucky enough to have some big-ass singletrack climbs that require that granny ring but pay off on the descent.

Had the uzzi vpx front der / 2X setup such that I could ride Northstar all day w/o a chain issue, so it is possible even though most of us are too lazy to figure it out.

 

[blindboxx2334]

Front deraillers are for xc bikes. Throw the whole thing in the trash.

plus a bazilllion

 

[300hp]

So, I tried a couple different 2x guides on my nickel, and have gone back to a 34t non ramped raceface ring, bashguard, and a blackspire stinger.

Perfect shifting to granny with a slight pause before making the shift, and excellent retention in all conditions. Best out of every combo I've tried, and the least expensive by a long shot.

 

[4130biker]

Perhaps a black spire e-type stinger? You'd mount the derailleur to the guide; might be worth looking at to see if its a lower position and/or if having the derailleur in a fixed position helps.
My understanding is that every two ring setup occasionally drops to granny under hard riding, so if its a priority not to do that, maybe a single 30t wolftooth ring and a mrp mini combined w a 36t cassette, which comes darn close to a granny gear. I ran the 30/36 on my sx trail last year, and it was low enough for single track climbs/

 

[frorider]

I have several 1x bikes, but I like having a 180 travel bike with low gearing in the quiver. And last year it worked pretty well with my old Heim mount and blackspire pulley...although occasionally the chain would drop down to the 22T ring.

The MRP 2X has such flexible plastic sandwiching the pulley that the chain gets out regularly. It's as if MRP released a product that had never been ridden on chunky terrain at speed.

I'll probably try a clutch rear derailleur, or will go back to the Heim setup which, although not great, at least didn't force me to get out tools during a ride.

 

[IH8Rice]

The MRP 2X has such flexible plastic sandwiching the pulley that the chain gets out regularly. It's as if MRP released a product that had never been ridden on chunky terrain at speed.

i have yet to drop a chain with my 2X even while downhilling

 

[frorider]

One local shop is saying that most MRP 2X's they've sold have not been working out well. I can't tell if some or all of those issues are setup related. On my bike the setup is perfect: pulleys perfectly aligned with chainrings, correctly sized arm, pulley assembly tucked in as close as possible to large ring, chain is short but not too short, etc etc. I've been dialling in drivetrains on my bikes/friends' bikes forever... but this is a weird issue.

The only non-perfect setup aspect is the height of front der but given the frame constraints that can't be lowered; and i've built a shim to take up most that vertical room. Since this is a chainstay front der mount, the high clearance of the front der (relative to the chain/big ring) is essentially constant as the rear wheel moves up in travel. Potentially one advantage of a standard front der mount is that as the axle path spikes upward and tries to throw the chain mass up, the decreased clearance of the top of the front der cage keeps the chain from flying up high enough to potentially derail on the upper (12 o'clock) section of the big ring. The downside is the noise that results.

 

[Casey-Ryan]

I would just throw away the chain guide and run a clutch der. I can tell by looking at your frame setup you have a lot of contraints. Also almost 100% of the time when I am trying to get a chainguide to work it results with spacer madness and my friendly pals beer and dremel tool. I have sort of giving up on them. Just MO

 

[IH8Rice]

I would just throw away the chain guide and run a clutch der. I can tell by looking at your frame setup you have a lot of contraints. Also almost 100% of the time when I am trying to get a chainguide to work it results with spacer madness and my friendly pals beer and dremel tool. I have sort of giving up on them. Just MO

so how is a clutch der going to protect his crank and chainring? if you give up that easily and resort to a dremel, then i can see how you wouldnt get it

 

[frorider]

called MRP in case they had other ideas. they were pretty honest about the taco 2X limitations...works best w/ modest travel (<160 mm) bikes running 2X crank chainlines. he confirmed that the MRP pulley cage is intentionally flexible so that if the chain falls to the outside of the big ring, it will snake thru w/o breaking the plastic cage. he also confirmed that the issue w/ some setups is vertical movement of the chain due to the top of the front der cage not being low enough, which allows that initial up-and-outward chain movement at the 12 o'clock position.

he also confirmed that one option is for me to go back to a roller/bashring setup like the MRP LRP (or my modified Heim setup) since the MRP 2X may not be well suited to this frame.

although i'm hearing issues with clutch assemblies failing, I'm going to try a shimano plus rear derailleur in combination with a thicker plastic shim under the top of the front der cage.