Di2 micro adjustments - anyone played with it?
 

When I purchased my bike (with Di2 shifting) the bike mechanic told me that he'd set the shifting and auto-tracking so there wold be no chain rub. However after riding the bike for a season I have noticed that when in the big chain ring, there does seem to be some chain rub. I'd like to do some adjustments to the Di2 unit/derailleur to alleviate the rub. Has

But here's the deal. I'm worried about mucking around with the shifting for fear of making things worse. The mechanic, when I picked up my bike, warned me not to mess around with the shifting as I can really screw things up. So, I guess here's my question.

1. Has anyone setup the shifting on their Di2?
2. If so, can I really make a mess of things as was alluded to?
3. Any resources I should check out online to make sure I know what I'm doing if I decide to tackle it?

Thank you.

Lots of home mechanics on these forums work on Di2 shifting systems.

If you don't feel confident then bring it to the shop. Having said that, it isn't very difficult if the directions are followed and the mechanic's warning not to mess around with it should be taken with a grain of salt. It can be messed up but it won't break and can easily be reset to factory default so that you can start again.

The first place to start with anything Shimano is the Manuals & Technical Documents website.

Manuals & Technical Documents

The second resource needed is the E-Tube Project website which is specific to Di2.

http://e-tubeproject.shimano.com/

Look up your system at the Tech Docs website. The Dealer Manuals will give complete setup and maintenance procedures and these will give you a better idea if it is something you want to tackle or not.

Adjusting limts and index on a Di2 system isn't rocket science or black magic. It is basic maintenance and I would encourage you. Look at the dealer manuals and let us know if we can help.

My own personal opinion is that for most people with basic mechanical aptitude, lack of a proper bike repair stand is a more important factor then is the prospect of messing something up when deciding whether a bike should be brought to a shop. It is an order of magnitude more difficult to work on shifting systems without a repair stand. There are many on craigslist.


-Tim-

Is it rubbing on the front derailleur cage? or is the alignment off center on the rear cogs?

If it's the cage, is it only when shifted to a couple of rear cogs?

As noted Di2 adjusting is not rocket science, but does require getting the rear wheel off the ground and being able to rotate the crank
freely. The main aim is noiseless operation and shifting end to end without over shifts. The main difficulty for the novice is inadvertently
having the shifter thinking it is in gear N when the RD actually is in gear N+/-1. Since the micropositioning is possible over +/- 16 steps
this is possible. Since your bike is already fixed by the mechanic, you will only need to do a few microclicks of adjustment to
achieve noise-free running. IME once a setup is optimized the Di2 system will not need readjusting for years. I haven't looked at
Shimano's tech manual for 3-4 yrs but the RD setup is a few paragraphs about page 25 or 30 in the 60-page manual.

The FD adjustment can be a little more persnickety as the FD is "more mobile" in its mounting with positioning vertically and
to a lesser degree angulation than the RD. Neither the FD or RD cages should be moved manually once mounted, you risk
damage to the internal gearing in the derailler motors. Only use the shifters. I have noted on mine that the FD seems a little
slower after 3 yrs to auto-adjust the FD cage when shifting down from the 32t to 28-25t cassette cogs so there will be some
cage rub noise for 6-8 sec before the cage moves when on the big ring.

From what I can tell I think it is the alignment of the rear cogs. I think the noise happens as soon as I'm in the large chain ring.

Thanks for the tips/suggestions. And yes, that is what I'm after - noiseless operation. The bike is completely silent when I'm in the small chain ring. But shifting to the large chain and boom. There is what sounds like chain drag. Although if i get off the bike and bring my eye down to look through the FD, I can't see any rubbing. So I'm left scratching my head trying to figure it out. Hence my thought to see if I can make some adjustments to the Di2 system.

So, your front derailleur cage isn't rubbing.
Adjustments will affect both chainrings, and it seems unusual that just the big ring is affected.

For rear adjustments, you first need to see where the chain is rubbing.

Look for rubbing:
Shift to the big chainring, and a middle cog in the back. Verify the front derailleur cage isn't touching the chain.

You should see a tiny gap between the chain's side plates and the next larger cog.

It's harder to see the gap on the smaller cog side of the chain. Try sliding a dollar bill down next to the chain and see if there's enough gap that it doesn't bind.

~~~

With the bike on a repair stand (or just hang it by the saddle nose, or have someone hold the rear wheel off the ground):

I turn the crank by hand very slowly. I'm looking for any hang-up when a tooth passes by the chain. An off alignment derailleur may show the chain getting pushed outwards slightly by a side cog's tooth, then popping down to it's normal location.

Thanks [MENTION=46547]rm -rf[/MENTION] I'll take a closer look at my bike this weekend. I went for a ride last night and the bike is completely silent when in the small chain ring. So you're right. I need to figure out where it is rubbing.

I remain unconvinced that the rub is not in the front.

It would be good to know if the noise happens in all rear gears or just some. With the chain on the big ring in front, does the noise happen all the time, only when on the large rear sprockets or only on the small rear sprockets?

My guess is that it rubs on the outside of the front derailleur when on the front big ring and rear small sprockets. This would be an H limit issue. Just a guess.

Sighting the chain through the front derailleur can be incredibly awkward. There is also a black plastic rub plate on the inside of the front derailleur which effectively quiets any rubbing sound, increasing the frustration factor.

I'll have a look at my bike on the bike stand this weekend to see if I can isolate the issue/problem and report back. Hopefully it's nothing serious and a quick fix.

I'll give a shop the benefit of the doubt they aligned the FD right, and torqued it down.

If it is only rubbing on the dinner-plate...the first thing my mind goes to is if the bracing screw and reinforcing plate are set properly (still). My second go-to guess would be a slightly bent RD hanger. Micro-adjusting is easy, but this doesn't smell like a micro-adjust problem over the internet. Once the indexing is set--it should never need screwed with unless something is broken/bent or replaced.

Great point. Certainly worth investigating.