Jet 9 RDO Shimano E2 Front Derailleur help, please!
Hi. I'm trying to build a 2012 Jet 9 RDO for my wife. I purchased this Shimano 2x10 Front Derailleur, the same one specced on Niner's complete builds:
SHIMANO XT M785 10SP E2 DIRECT MOUNT BOTTOM PULL
My problem is, as you can see in the picture, the Shimano E2 front derailleur has oval mounting holes, which allow for two different mounting positions. Depending on chainring teeth count, you mount the derailleur either with both bolts at the top on the ovals, or alternatively with both at the bottom. The standard E-type FD comes with an oval nut to snug up a standard bolt once you've picked a position. The E2 type specified by Niner doesn't come with that part.
The following tech docs shows what I mean (sorry, there is no relevant document for the M785 that shows the part, but this M770 is very similar.) Mine looks like the front derailleur in the bottom left. As you can see, it lacks part #7, the oval washer/nut, that the derailleur on the bottom right has:
As a consequence, the front mounting bolt for this derailleur won't snug up securely on the Jet 9 RDO frame. I suspect that I need the oval nut to make this work, but Shimano doesn't have a M785 2x10 derailleur in E type--only the E2. So that leaves me with the thought that I need to buy a second derailleur in order to get this M785 E2 type to work--just for the darn oval nut. That can't be right, can it?
Any help is appreciated.
From looking at the Shimano pdf, it would seem that oval nut is only meant for use when you have the model with the BB plate as it is used to secure the plate. In what way is it not snugging up when you use the Niner supplied bolts to mount up the derailleur? Only thing I can think of is you may need a washer behind the bolt heads to enhance the clamping surface of the bolts, but otherwise I don't see why it shouldn't work. Because of the oval holes you'll need to move the derailleur to the appropriate height before tightening the bolts.
Thanks for the response. The front of the two mounting holes simply doesn't have enough "lip" on the front to allow the bolt to snug. As a result, the bottom pull derailleur pulls the derailleur down into the lower position when you try to use it. Looking at the diagram, the oval washer would seem to fix the derailleur in place.
Originally Posted by kwarwick
I do realize that the oval washer is meant for the bottom bracket plate for the E style. However, the only other thread I could find on the subject had a person taking apart the E style (with bottom bracket plate).
See, for example:
Jet 9 RDO front derailleur?
From the first post to that thread:
And another thread about S3 (Sram's equivalent to E2) mounting:
After removing the BB plate it bolts up as expected...
S3 direct mount front derailleur installation
Yeah, I can definitely see where a couple of oval spacers could be helpful in fixing the height of the derailleur. I guess I'm still not understanding what you mean by not enough lip to allow the bolt to snug. Are the mounting bolts bottoming out before you can tighten them enough or is it just that the bolt heads just aren't big enough to get a good grip on the derailleur? Could you take a photo of the situation to help us better understand the problem?
I think he means the bolts bottom out before they can be snugged up against the derailleur. Do you have a picture? I am using the same set-up with no problems so far.
I was using the m785 (without bb tab) which should the same one with no problems. You just need to use both bolts and the mounting bracket that came with your frame. Here's the front mech I was using until I switched to a 1x10...the bolts don't bottom out before the der is snug. I'm guessing your not using the backing plate that came with your frame? Or maybe you have cross threaded it or have some dirt or locktite inside the thread preventing you from threading it all the way? I'd def recheck your work, it should work fine.
Didn't your frame come with the plastic insert that goes between the frame and FD? This takes up the "slack" in the length of the bolts.
edit...ooops. didn't see the prior post
Here's a pix of my Jet 9 RDO's FD. The pix was intended to look at the new shift kit but you can see the FD from here. No problem with the mount at all. The front mounts itself should be set to accommodate the staggered design of the bolt holes. Working just fine for the past month.
Consider the problem solved--I just need to torque the bolts more.
Hey guys--I want to thank each one of you for your help!
I am using the mounting bracket that came with the frame. I guess my problem is probably that I don't have a 3 mm bit (they're somewhat rare, I guess) for my torque wrench to fit these bolts, and I've been a little nervous about over-torquing bolts into this frame. I'm going to pick up the Park tools bit set that includes a 3mm bit, and torque the bolts to the specified value.
Thanks to everyone for confirming I have the right FD!
I shredded one of my bolts by using 1 more Nm of toque they required so go easy on the bolt head.
Which forces me to ask....does anyone know how to get a replacement for these bolts? Assume I hit up Niner???
I'd just try to contact niner...they have always been extremely helpful and want you to be a part of the "niner nation" (lol, thats always the first line in the reply emails) and be out actually riding the bike...not trying to hunt down a small part. I'm sure theyd send a replacement for little to no cost. Or you can always try sourcing the same size bolt.
My mrp 1x came with some similar bolts which worked perfect and I might have an extra laying around. I also have an extra original bolt that I'm not using if you wanna cover the shipping costs. Always willing to help a fellow rider. It's a fairly common size and doesnt need to be the exact one niner provides...considering my mrp guide supplied bolts to use...they seem to work on both the mrp guide and the front mech. Let me know if I can be of help or if you need me to get you the exact size and pitch.
As far as over torquing...just make it snug and use a drop of blue locktight...it's a pain trying to get a torque wrench in there without removing the cranks. After working on bikes are a while you can usually go by feel. If you feel more comfortable using a torque wrench, spend a little more and get a high quality one. The low cost ones arent very accurate which maybe over torque them without knowing. That's one thread I wouldn't enjoy trying to repair...due to the small size.
I think both WoodstockMTB and I received bad bolts with our frames. I got my Park SBS-1 bit kit today with the 3 mm bit for my Park torque wrench, and the bolt heads are simply too soft to be brought up to the specified torque.
My derailleur pivots on the middle bolt the front is so loose. Will try to call Niner tomorrow.
In case anyone is interested, my frame's inserts where too shallow. Niner support instructed me to remove 2mm from the bolt, and all appears to be well.
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