alsv85

Hi.

im doing an di2 build on my bike and have encountered a problem.
the fit between hub and rear cog is so tight i cant freewheel.
Is there anyone that encountered the same issue and have an fix for it?
The hub is shimanos 11speed di2 and the rear cog is gates di2 compatible 28T cog.

RobertUI 

Without seeing it, I first think that maybe there's a spacer on before the cassette? Sounds like the cassette needs to sit further on the freehub body.

dsbrantjr

Have the hub splines, especially where the larger cogs sit, gotten chewed up due to the pressure of the cogs against the splines? Sometimes the splines need to be cleaned up with a file for the cassette to seat properly.

alsv85

i took the wheel of and removed everything, it seems the snap ring barely fits the slot as intended, its getting belt drive so its not an conventional cassette.
but im pretty stuck scratching my head att the thing.
ive read the manual and the washer and snap ring is supposed to fit, but the instruction is not for the gates system so i dont know.
i was hoping someone here had an alfine gates build because there arent any on my native bikeforum

alsv85

It works well without the dustcap and hub cover(plastic ring that fits before the cog). But arent those to important for the protection of the hub?

squirtdad

no hands on, but some links

sheldon https://www.sheldonbrown.com/alfine-11.html

a start on finding the shimano tech docs https://si.shimano.com/#/en/search/K...me=Alfine%2011

Iride01 

What frame are you putting it in? Did it ever have a regular Alfine hub in it of that size? I'd think your frame just won't fit that hub or maybe you left a spacer off the axle.

You are talking about this Alfine Di2 aren't you?

https://bike.shimano.com/en-EU/produ...-S7051-11.html

alsv85

Thats the correct hub yes.

The problem occurs even when the wheel is off the bike, originally it came with an 8 speed mechanical alfine hub so its prepared both for the belt and the hub(its the same old)

The instructions only shows installation with chain so i dont know if theres something special when u are using an belt instead or simply the rear cog isnt machined correctly i dont really know.
In the pictures from the instructions it shows the installation with and without the cover so im a bit confused over that.

alsv85

So i tried my mechanic but he have no experience of the system so he couldnt help, i have mailed shimano and gates and are waiting an response. There is comatibility problem regarding other systems and in shimanos instruction they mension that the solution is for cogs from 18t to 23t.

*Scuba 

Currently, Shimano only has 6 different cog sizes for the Di2, IGH systems. 18t, 19t, 20t, 21t, 22t and 23t. Shimano also has very specific ratios that they want riders to stick to.

I have not installed Gates cogs on to Shimano IGH before and without pictures, won't be able to assist you.

squirtdad

it looks like there is a really good chance your frame is not compatible with the di2 hub.....

https://www.gatescarbondrive.com/~/m...-di2.pdf?la=en

from the 2 page tech bulletin

Gates introduces the new CDX™-CenterTrack™ Di2 component group. The new Shimano Alfine Di2 electronic shifting system requires a special belt line. Gates now offers front and rear sprockets, as well as a crank assembly to fit this system. It is important to note that not all belt drive compatible frames will work with the Alfine Di2 system. Due to placement of the motor unit, the belt line for the Alfine Di2 moves inboard from 43.7mm on the standard Alfine to 39.8mm on the Di2 model, a change of 3.9mm. Because of this inboard movement, frames that fit the standard Alfine series hubs will not necessarily fit the new Di2 series. In addition to this 3.9mm offset, an additional 2mm of clearance between the front sprocket and the frame must still exist. Refer to Figure 3 for the belt line specification.

alsv85

Problem solved:
So gates explained that the plastic ring is a chainguard and is unnecessary when using an belt and without the ring i could mount the cog with the dustcap attached to the hub.