Shimano Alfine 11 IGH issue in gears 4 and 6

[thenorthwind]

I have an odd problem with my Alfine 11 which I can't find any other experiences of on internet to help me diagnose the problem. I'm wondering if anyone here has experienced anything similar, or has any clue as to the cause?

All gears except 4 and 6 work fine, and seem to be the correct ratios, but shifting up into 4 or 6, the ratio actually reduces. They still transit power, just at a lower ratio than expected. They feel solid, with no slipping feeling, and all the gear shifts are smooth.

To try and nail down the problem, and see if there were any other ratio problems I couldn't feel, I measured them all in the stand by turning the cranks as close to exactly 1 revolution as possible, and counting the wheel revolutions as accurately as possible. The results I got were, from gear 1 (lowest) to gear 11:
1.219
1.563
1.750
1.250
2.250
1.563
2.906
3.281
3.719
4.188
4.750

Note the unexpected low ratios in bold.

This seems to roughly match with the table of ratios from Brucey here after I take into account my 42/20 gearing, apart from 4 and 6.

I'd hoped to be able to identify a common element from the gear configuration table (also on Brucey's page on Sheldon's site) but I can't.

A brief history of the hub: I bought it used, seemingly in very good condition in the winter. Before I built it into a wheel, I stripped it down (it seemed well-lubricated and no excessive contamination of the oil), flushed it, refilled it with EP90, replaced a plastic sealing part that was damaged, greased the bearings, and reassembled. It's given me a few months and probably hundreds of miles of good service (not very long in the grand scheme, but enough to believe it didn't come to me with a fundamental problem).

When the problem first occurred, I took the internals out, mainly to see if there was something obvious broken or jammed, flushed it and refilled again, which had no effect on the problem. Then after a week or so, it mysteriously disappeared. It appeared again on my morning commute this week, only to have disappeared before I arrived 3 miles later. I can't find any correlation with conditions (e.g. heat).

It doesn't appear to be a cable indexing problem. All the shifts are fine, and slight adjustment in either direction only results in the sort of poor shifts you'd expect from slight misalignment.

[gazza_d]

Hmm. Not sure on any specific cause.
I do remember Brucey saying that, 99%+ of all IGH issues are either cable or shifter related.

I would check that the cable is definitely fine, shifts without issue and.isnt kinked or has any other issues.

I'd also check that the cassette joint is clean and gunge free. I've had issues with mine when I've accidently got lube on it which then dries and becomes a little sticky.

Also check that the cable groove on the cassette joint is clean and the cable is properly seated.

Gary

[peasantpigcyclist]

I can't help. However,my alfine11 started to slip in 2nd,4th and 6th and progressively got worse, fitted new cable and shifter. No difference. I haven't got round to dismantling it. It was a week before I was due to ride in the lake District.
As I was having issues with 4 of my bikes with Shimano hydraulic brake calipers also,I replaced the front brake with a new Shimano caliper on this bike and went out and bought a rohloff hub for it instead. (I have been becoming unhappy with several Shimano components quality lately)
I too couldn't find anyone online with same problem also.
I would be interested to find what was the problem with yours.
I will keep you posted if I discover my z hub issue.

[thenorthwind]

Thanks Gary, appreciate your reply. I'm 99% sure it's not a cable/shifting issue though. When the problem isn't there, the shifts are all nice and smooth, and even when it is, they still are, just the ratio is wrong. I adjusted the cable tension a bit in either direction to see if it had any effect, but it didn't - just made the shifts worse. Also, the ratios I'm getting in 4 and 6 don't correspond to the ratios either side, they're completely different - though I suppose it's feasible it could actuate some elements of the shift, but not others. I cleaned the cassette joint when I stripped it down. Nevertheless, I'll have another look.

I will keep you posted if I discover my z hub issue.

Cheers. If you can feel yours slipping, rather than driving in a different ratio, it sounds like a different problem, but there might be some link since it's affecting (some of) the same gears. I'll update if I get anywhere with this.

[Sum]

Brucey has also posted about the A11 in the Alfine 11; how it works (long) in the Technical Too Good to Lose section. I find the gear configuration table there easier to read than the table on Sheldon's website.

Just looking at gears 1-6 for now, the common element used by gears 4 & 6 is the locking pawl for the third sun gear that pops out of the axle (see the L in the S3 column). If this doesn't work and lock S3 then gears 4 & 6 will behave like gears 1 & 2, which is consistent with the OP's gear ratio measurements.

S3 is also locked for gears 9 and 11 to work, in conjunction with clutch C1 being engaged . If S3 is not locked then gear 11 becomes gear 7, and gear 9 becomes the normally unused direct drive gear, if I've read Brucey's description correctly. However the OP's measurements show that these gears are not affected.

As the problem seems intermittent i.e. it comes and goes, I'm wondering if the S3 pawl sticks and doesn't engage in gears 4 & 6, but the fault is marginal enough that it somehow doesn't happen when the clutch C1 is also engaged for gears 9 & 11. Maybe the engagement of the clutch unsticks the pawl? (This may seem a bit like I'm clutching at straws I know - no pun intended.)

Later edited for clarity (and for the unintended pun.)