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I have a Shimano Alfine 8 IGH. The other day, I noticed excessive slack in the chain. I saw that the hub axle had slipped and moved forward in the rear-facing dropouts, causing more slack that I had intended.

I had previously torqued the non-turn/cap nuts to 45 Nm (the max per Shimano spec). Thinking that maybe this was conservative and not enough to hold the wheel in place for my bike, I repositioned the wheel and torqued to 55Nm. I don't know if that was a mistake or even related to my next problem.

Riding the bike the next day, it felt like there was more resistance to pedaling than before. After riding, I looked at the wheel; the axle had not slipped. The chain looked like it had about an inch of play; so not overly tight.

I started to wonder if there might be a problem with the hub bearings. I took the wheel fully off the bike. Holding the wheel in one hand, I started to turn the sprocket in reverse with the other. There is significant drag when trying to freewheel the sprocket. I can not impart any "spin" at all to it; it will only turn as long as I am actively turning the sprocket with my hand.

By contrast, I have a brand-new freewheel for another bike. I know that if I hold the freewheel from the center, and rotate the sprockets backward, I can cause the stack to spin fairly freely.

I have read that IGHs often have more resistance/drag than external gear systems. I also don't know how much resistance my Alfine 8 gave to turning before I noticed any problems. I am suspicious though that something is wrong/mis-adjusted with my hub to give this resistance.

Here is a link to the dealer manual for reference, if helpful:

https://si.shimano.com/en/pdfs/dm/SG0004/DM-SG0004-06-ENG.pdf

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  • Whats the mileage on the hub? Have you been doing the oil changes ?
    – Criggie
    Aug 16, 2022 at 19:09
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    @Criggie no oil in the 8sp, ya know.
    – Noise
    Aug 16, 2022 at 19:15
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    I've done no prior maintenance on the hub. It's grease packed. I've had it ten years and I'd guess between 10k-15k miles. Aug 16, 2022 at 19:18
  • @noise Good point - should read "have you serviced the hub?" which is an "oil dunk" on an alfine8 It is some fancy engineered grease/oil combination, not strictly oil or grease, but a combination.
    – Criggie
    Aug 16, 2022 at 22:30
  • The hub is not hermetical and main bearings are near its edges, so they suffer first from dirt and moisture. Also, its factory grease has suspicious quality. While in good condition, it spins easily, like usual bearing. The main problem of this hub is insufficient precision of planetary gears driver. This causes satellite needle bearings to wear very fast. This can be the cause of tight pedaling while easy freewheeling.
    – Vladimir
    Sep 3, 2022 at 15:24

2 Answers 2

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At 15,000 miles with no maintenance, the best case scenario is it's long overdue for its oil dunk and bearing service per the document you linked to, which Shimano recommends every 2000km or yearly, whichever comes first. Lack of lubrication is certainly causing increased drag. At that mileage with no maintenance it's also very possible that parts are damaged. In practice their numbers aren't magic and in many climates one can get way with a longer interval, but that's too much.

Shimano internal hubs sometimes need to have their axles and acorn style axle nuts cleared of any little flakes or chips, and then relubricated. 55nm is too much torque, and it shouldn't need that with the threads properly clean, greased, and in good condition. The flatted axles can shave material way from the axle nuts over time with removal and reinstallation, and I've encountered ones before where the threads on the nuts were getting to be in bad shape and in need of replacement, which is no big deal.

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    Thanks! I hear you about maintenance. I’ll have to see whether I can do it myself or need to take it to the LBS. I’m curious whether the increased torque could have thrown off the bearing adjustment, since the resistance change happened after my torque adjustment. I wasn’t noticing any particular resistance before this. Aug 16, 2022 at 21:12
  • @NedRuggeri hokkaidowilds.org/… Looks relatively simple, you just need the tools and special oil. And lots of rags. Should be done every 5000 km or 12 months. The potential problem is if the internals have been damaged by running for so long on old lubricant - it might be damaged beyond saving.
    – Criggie
    Aug 16, 2022 at 22:31
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I put the wheel back on the bike and put the bike in a stand. Indeed the wheel rotated CCW when backpedalling by hand. I could get the wheel up to a good clip while backpedalling.

Likewise, pedaling forward by hand rotated the rear wheel CW. Stopping pedaling caused significant braking action and the wheel to stop rotating.

I then degreased and cleaned the hub. I repacked with grease, and dunked in ATF. I put the wheel back on.

That didn't seem to help very much.

I then adjusted the cup-and-cone bearing from the non-drive-side. The first adjustment allowed the axle to shake, but the wheel spun freely. The second attempt eliminated the shake of the axle, while allowing the wheel to freewheel with very little drag.

The maintenance could not have hurt, and pedaling does feel more efficient.

However, I believe the problem all along was that the bearings needed adjustment.

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    Nice job at getting at the fix with the other answer provided AND good human intuition as to the real issue you were having to resolve the problem. Bearing adjustments are almost always worth investigating because when they are out of adjustment the possibility of damage increases, not to mention the bike does not perform as it should..
    – Ted Hohl
    Sep 4, 2022 at 17:10

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