11 Speed Di2 Front Shifting Troubles

Discuss light weight issues concerning road bikes & parts.
goodboyr
Posts: 1388
Joined: Wed Jan 10, 2007 10:56 pm
Location: Canada

by goodboyr

Height looks ok, I doubt thats the issue. Like I said, your symptoms sound like lack of parallelism and weak FD support.

by Weenie


LoggingMiles
Posts: 84
Joined: Sun Dec 01, 2013 3:46 pm

by LoggingMiles

Thanks, I will remove the chain catcher and check parallelism again and see if that helps any. I will post back with my results.

LoggingMiles
Posts: 84
Joined: Sun Dec 01, 2013 3:46 pm

by LoggingMiles

For the moment it seems the chain catcher was the issue. I removed it, reinstalled the Derailleur with the original shimano bolt and checked paralleism again. Shifting seems much improved on my very short test ride.

Not only was shifting improved, but it allowed me to tighten the high limit a LOT more than I was able to before. Would that be a normal response to the reduced flex on the cage? Also, how does the chain catcher contribute to flex in the FD?

I am going to go out for a longer ride in an hour or so to see if the problem is resolved.

Thanks for the suggestions. I will let you know if that resolved the issues.

goodboyr
Posts: 1388
Joined: Wed Jan 10, 2007 10:56 pm
Location: Canada

by goodboyr

Yup. As I said, some chain catchers have smaller bolts or cause flexibility by making the fixing bolt engage less threads.

Zigmeister
Posts: 921
Joined: Mon Jan 24, 2011 8:09 pm

by Zigmeister

Im using an exact setup you are. Stock bolt/mount plate, then no washers and the catcher in between.

Also using the stock support plate, have it parallel, and run QRings, no issues with shifting. Running 9070 Di2.

Interesting removing it solved the problem.

LoggingMiles
Posts: 84
Joined: Sun Dec 01, 2013 3:46 pm

by LoggingMiles

I was not using the stock bolt. I was using the one from K-Edge. In fact, I am still not using the stock bolt, I am using a M5 bolt that I have from another build that is the same length as the Shimano bolt. My FD-6870 did not come with a bolt, so I am actually looking around trying to find a place to order a bolt/plate.

Gearhead65
Posts: 112
Joined: Sat Jan 23, 2010 1:24 am
Location: Evansville, IN, USA

by Gearhead65

FWIW...I'm using a K-Edge (new style) chain catcher on my 6870 also. Just a thought...maybe when removing the chain catcher, possibly set the inward 'pre-angle' more, before screwing in the support bolt. Thus providing more rigidity?

I did notice installing the chain catcher it comes with a short bolt and a long bolt. The long would have bottomed out on something inside the FD without fully tightening unit to the bracket. Had to use the short bolt.
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LoggingMiles
Posts: 84
Joined: Sun Dec 01, 2013 3:46 pm

by LoggingMiles

OK, I got the new shimano bolt and radius washer in today from the shop. I installed that. I have also reset parallel. Shifting is better, but after longer test rides it is still not where I think it should be.

I snapped a few pics as was hoping you guys could check to see if I have parallel set correctly.

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goodboyr
Posts: 1388
Joined: Wed Jan 10, 2007 10:56 pm
Location: Canada

by goodboyr

Wow. Looks fine. I am now officially stumped. With the 9000 crank the shifting should be perfect. Sorry to repeat, but I assume you started with the FD angled in and then used the support bolt to get it parallel thus ensuring the support bolt was bearing the load. Other than getting it as low to the chain ring as possible, I'm out of ideas.

LoggingMiles
Posts: 84
Joined: Sun Dec 01, 2013 3:46 pm

by LoggingMiles

I did start off a degree or 2 toe in and let the support bolt push it out a bit like it states in the dealer manual.

I am using a DA Cassette and Crank but 6800 chain. Would a 9000 chain have the potential to help?

I also checked the torque on all the chainrings and checked for play in the BB. Both good.

goodboyr
Posts: 1388
Joined: Wed Jan 10, 2007 10:56 pm
Location: Canada

by goodboyr

Chain wouldnt make a difference.

LoggingMiles
Posts: 84
Joined: Sun Dec 01, 2013 3:46 pm

by LoggingMiles

I am a little under 1.5mm now height-wise. I may try to lower it. Other than that, I guess I will just deal with it. I thought at first maybe I was just being picky (after just spending all that cash on Di2!), but I do have a frame of reference, as I rode a Madone that was newer than mine with 6870 this weekend. Front shifting was superb.

My symptoms now are just a tad different. It just seems that on occasion my chain will chatter/grind/etc for a brief moment before grabbing the chain ring and riding up on to the big ring.

Zigmeister
Posts: 921
Joined: Mon Jan 24, 2011 8:09 pm

by Zigmeister

Like I said, I run Qrings...if anything shouldn't shift worth crap, it would be those...but it is near flawless. The only issue with QRings is due to the lower teeth as they come around, shifting will delay, or "mis-catch" slightly, but the larger part comes around of course and it jumps right on. So it is a slight hesistation/catching issue very intermittent...but I've learned to shift at a specific point in the stroke, as you come around to the largest portion, ease off the pedal slight on the downstroke mid-way, and it catches almost perfect every time.

So basically I've learned to always have the largest/highest tooth coming around under the FD cage almost every time. Well, I try, not possible in every circumstance, but 80% of the time I do that.

Setup parallel, 9070 Di2. CN-9000 Chain, Sram OG-1090 Rear Cassette. Height is about 1mm above the very largest tooth at the biggest point of the QRing.

Keep working with it and tweaking it, you will get it eventually.

Last resort, might try different chainrings as a test...might be the issue. The way it is machined/ramping etc...could be causing the intermittent issues. I don't think there is such a thing as perfect every time shifting after 30yrs of riding. But I must say this new 9070 Di2 is about as close as it gets.

LoggingMiles
Posts: 84
Joined: Sun Dec 01, 2013 3:46 pm

by LoggingMiles

So, another couple of things.

1. I am running a 52/36 crank. The bike I test rode (where shifting was flawless) was 53/39. Does performance suffer that much on a compact, or in this case semi-compact, crank?

2. I was cleaning the bike up last night while I was making more adjustments and checking for other possible issues. I also had someone else ride it who immediately said something was off with the front shifting. When cleaning, I noticed a lot of metal shavings coming off the chain. I have never experienced this in 12+ years of cycling. The DA crank already looks to have some wear on the inside of the small and large chainrings. There are less than 200 miles on the crank/rings, which is where I suspect the shavings are coming from. Is this normal on a new crank?

by Weenie


goodboyr
Posts: 1388
Joined: Wed Jan 10, 2007 10:56 pm
Location: Canada

by goodboyr

1. There is a slight difference in performance, but you are running shimano rings so its imperceptible. I am running praxis 52/36 on my 9070 system and the shifting is perfect. I can shift under full load without concern.
2. This is not normal.

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