Shifting di2

Discuss light weight issues concerning road bikes & parts.
Timmy269
Posts: 184
Joined: Tue Nov 25, 2014 2:34 pm

by Timmy269

Today another ride. I have all the ride looked to my Garmin with the display on the gear ratio. It looked like if the rd changes the gear, it didn't changed on my Garmin. When I was riding on my 7t, the garmin displayed 7th gear. In a flat road the changed itself and on the display of my Garmin still was 7. I rode a long time with a chainring that was worn out and had also that problem. Now I have new chainring and I thought the problem would be solved but it didn't. I didn't changed the chain and cassette because I had only riden 2000km with them on my worn out chainring. I measured the chain ring with a tool and it's fine, but could that be the issue of my problem.?

by Weenie


2old4this
Posts: 359
Joined: Mon Jan 13, 2014 7:26 am

by 2old4this

At the expense of stating the obvious, it is something on your drive train. You'll have eliminate the possibilities one by one...

You've already ruled out the adjustment of the rear derailleur, as well as the limit screws.
Check your derailleur hanger, and align it if necessary (a buddy of mine had his bike tripped over during a century. His gear was changing randomly. After the ride he said he fixed it by aligning the hanger...)
Check your chain, does it have any sticky links?
Change your cassette. I've seen some teeth bending ever so slightly that made the whole thing impossible to adjust.
Check your di2 connections. Once I used a very short cable between the junction and the handlebar (was saving about 2 grams..) It was not enough to disconnect but was causing random behavior (some no responses, some extra shifts...)
Check your connections, and if possible, change you cables and the junction boxes.
Disconnect the di2 cable from the shifter, and use a climber shifter.

Those are the simple and less costly things to try. If they don't work, I am afraid, you have to try changing the rear derailleur and the battery.

moonoi
Posts: 481
Joined: Sat Nov 21, 2015 3:04 pm
Location: Earth

by moonoi

Timmy269 wrote:
Sun Jul 15, 2018 8:43 pm
Today another ride. I have all the ride looked to my Garmin with the display on the gear ratio. It looked like if the rd changes the gear, it didn't changed on my Garmin. When I was riding on my 7t, the garmin displayed 7th gear. In a flat road the changed itself and on the display of my Garmin still was 7. I rode a long time with a chainring that was worn out and had also that problem. Now I have new chainring and I thought the problem would be solved but it didn't. I didn't changed the chain and cassette because I had only riden 2000km with them on my worn out chainring. I measured the chain ring with a tool and it's fine, but could that be the issue of my problem.?
I would change your chain as well, it could be that using it on your worn out chainrings has damaged it already and thats why you are getting the issue you have. It's also the cheapest option out of everything else to replace to try and troubleshoot.

Timmy269
Posts: 184
Joined: Tue Nov 25, 2014 2:34 pm

by Timmy269

I ordered a new KMC x11EL chain and I have a new cassette. I will replace the old ones and take a ride at wednesday.
I hope that will solve the problem :cry:

2old4this
Posts: 359
Joined: Mon Jan 13, 2014 7:26 am

by 2old4this

This happened to me on the front derailleur, twice...

Last weekend, the FD shifted from big ring to the small one (not a chain drop; I heard the servo running. It simply shifted to small ring, it was under the moderate power, if that makes a difference.) I do not know which rear gear I was in (either 2nd or 3rd) since I kind of panicked and tried to compansate.

Went back home, stripped the drive train, cleaned everything, took out all the di2 wires out (no short cables, no damaged ones), checked each component with PCE1. While I was at it, I've checked the rear derailleur hanger alignment; perfect. Checked the chain; no sticky sections. Reconnected di2 components (used junction boxes from another bike, replaced FD di2 wire), installed everything back, adjusted the FD and RD, and checked the system with PCE1.

The bike was ready Saturday morning. We did a 2K ft ride. Everything was perfect. I took the bike out this morning again for a 3K ft ride. FD ghost shifted towards the end. Again, not a chain drop; I heard the FD servo running and changing the gear.

This time, I am sure I was on the 3rd rear gear. The chain was not touching the FD.

I think either my FD or the battery is bad. Can you guys think of anything else?

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