Ultegra Di2 indexing

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pedalbasher
Posts: 123
Joined: Wed Oct 02, 2013 10:17 am

Ultegra Di2 indexing

Postby pedalbasher » Wed Feb 19, 2014 23:31 pm

Hi

I just bought some new wheels and fixed an Ultegra 12-25 cassette.

My bike has Ultegra Di2.

Previous cassette was an 11-28.

When I shift through the gears on the new cassette, the chain moves happily up to the penultimate sprocket but won't move into the 25. Conversely at the other end of the spectrum, it will shift down to 12 and then off the end of the cassette (worrying). I.e. the 10 shifts are out of sync with the cassette by one sprocket.

Please could someone help me set the rear derailleur up correctly. Is there a simple way? I am wondering whether I need to put another spacer in behind the 25 cassette.

Thanks v much.

Semantik
Posts: 315
Joined: Sun Feb 24, 2013 09:49 am

Re: Ultegra Di2 indexing

Postby Semantik » Wed Feb 19, 2014 23:53 pm

you didn't inadvertently remove the thin 0.75mm spacer from the freehub when you removed the old cassette?

pedalbasher
Posts: 123
Joined: Wed Oct 02, 2013 10:17 am

Re: Ultegra Di2 indexing

Postby pedalbasher » Thu Feb 20, 2014 00:06 am

Nah - I've put new wheels on, so new free hub. There's def a small metal spacer behind the cassette now (i.e. I put it on the free hub on the new wheels before installing the cassette).

pedalbasher
Posts: 123
Joined: Wed Oct 02, 2013 10:17 am

Re: Ultegra Di2 indexing

Postby pedalbasher » Thu Feb 20, 2014 00:07 am

Should have clarified - by "I've just bought new wheels", I mean I have literally bought a new wheel set, not a new bike! I.e. I have replaced the wheels, and with them obviously the free hub!

Semantik
Posts: 315
Joined: Sun Feb 24, 2013 09:49 am

Re: Ultegra Di2 indexing

Postby Semantik » Thu Feb 20, 2014 08:48 am

Sounds like the rear mech is still selecting 10 ratios but starting and ending in the wrong position.

Did you select top gear (smallest sprocket position) using the shifter before putting wheel in?
If you did this, and the chain still runs badly in that gear -and was ok before- you know it's nothing YOU have altered and must be the chainline has changed and/or limit screws need re-setting.

Also,if it's a Mavic WHEEL (??) no spacer needed on those.

pedalbasher
Posts: 123
Joined: Wed Oct 02, 2013 10:17 am

Re: Ultegra Di2 indexing

Postby pedalbasher » Thu Feb 20, 2014 11:00 am

Cheers. You're exactly right. It's selecting 10 ratios (and moving smoothly between each sprocket) but starting and ending one sprocket out.

They're Reynolds wheels. I just put one spacer behind the cassette.

Not sure I selected smallest sprocket before putting the wheel in (I think I did, but can't be sure now...) I'll try that later.

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Me-109
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Joined: Wed Jul 25, 2007 15:39 pm

Re: Ultegra Di2 indexing

Postby Me-109 » Thu Feb 20, 2014 11:06 am

Wheels designed for 11s and in need of an extra spacer behind the cassette?

pedalbasher
Posts: 123
Joined: Wed Oct 02, 2013 10:17 am

Re: Ultegra Di2 indexing

Postby pedalbasher » Thu Feb 20, 2014 11:07 am

Me-109 - thanks, that's the other possibility. Should be as simple as that, one spacer to compensate for the extra sprocket?

Semantik
Posts: 315
Joined: Sun Feb 24, 2013 09:49 am

Re: Ultegra Di2 indexing

Postby Semantik » Thu Feb 20, 2014 11:39 am

OP- the following is useful info on all things 11 speed and which spacers you will need.

http://www.slowtwitch.com/Tech/Cassette ... _3257.html

pedalbasher
Posts: 123
Joined: Wed Oct 02, 2013 10:17 am

Re: Ultegra Di2 indexing

Postby pedalbasher » Thu Feb 20, 2014 11:53 am

Thanks a lot for that - geeky but the table is pretty useful. I can only assume the new Reynolds freehub is actually 11sp-only and therefore I need both 1mm and 1.85mm spacers behind the cassette. This might explain why there were 2 spacers in the little plastic bags supplied with the rim tape and skewer for each wheel... obviously I was in too much of a rush to bother with those :)

pedalbasher
Posts: 123
Joined: Wed Oct 02, 2013 10:17 am

Re: Ultegra Di2 indexing

Postby pedalbasher » Thu Feb 20, 2014 22:15 pm

Ended up putting 3 x standard narrow (0.5mm?) spacers behind the cassette, played around with the hi / lo limit screws a bit and also tinkered with the di2 set-up (i.e. the micro-adjust function). Seems to be working nicely now, so cheers for the advice.


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