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I have a 2012 Spot Acme and it's been great, everything is still smooth and working well into its second winter. However I picked it up to bring it into the office a week ago and noticed grease all over my hands, just like a chain would do. Here's a picture.

greasy black stuff all over the belt

It's like a heavy black graphite grease, definitely oily and not just dirt. There are no signs of leakage from the Alfine SG-700 hub or the bottom bracket. (Hub oil is a much lighter product more like automatic transmission fluid and there is only 25cc of it.) If either the hub or the bracket had leaked all its lubricant I would expect at least some creaking or other noise but it's still all smooth and silent.

I haven't ridden in anything but normal wet weather. If I had gone through a big puddle of grease I would expect to find some on the frame, my clothes, experience disc brake issues - but everything else is clean.

Gates technical support says that the belt would not deteriorate so quickly and even if it did it would not release any residue, and that it can be removed and cleaned with no ill effects.

Any suggestions as to what I should check next? If this stuff came out of the bike then something needs some attention. If it didn't, how can it be confined to the belt and sprockets?

Update: It almost certainly is a leak from the Alfine 11 hub, Spot Bikes say it has been known to happen and there are a few search hits with people describing exactly this problem. The bike is in for service with a local shop now (under warranty), I'll update again with the outcome. Annoying to be without a bike...

Second Update: I'm picking up the bike tonight, after a cost-free fix under warranty. The hub was inspected by Shimano's representative and pronounced OK once the seal was replaced. The Gates drive components were decontaminated and everything is said to be fine now. If I experience any further leaks, shift issues or if exposure to Shimano's $$$$$ hub lubricant has had any negative effects on the drivetrain I'll continue the saga here.

Third Update: I've put a few hundred km on the bike after the fix and everything seems OK in terms of seal. I might be mistaken but it seems be slipping a bit more often when I put a lot of power on the pedals. I'm watching it and will start making some noise about a complete replacement from Shimano if it gets worse.

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Thanks for the update; I have an Alfine 11 and will be watching for this. Good luck with the fix! –  dsalo Apr 22 at 23:25
Maybe post that as an answer so this can be an answered question. Guess that light hub oil combined with a little dirt looks like grease. Even when you oil a chain with light oil it seems to turn to a more of a grease. –  Blam Jun 22 at 17:01

2 Answers 2

What you know right now is that there's quite a lot of it and it's quite greasy. Which is useful, but not especially useful.

One thing that occurs to me is to question whether someone else might have oiled the belt for you? Has it been in a shop, or do you have someone else in your house who maintains a bike? Is there a source of fumes where you store your bike that could be breaking down the belt? Or could someone have spilled chemicals on it?

There's really only a few possible sources of that grease on your bike, which I guess is why you're confused. The bike is new enough that the bottom bracket will be a sealed unit, so there should be no grease coming out of that. The hub should be sealed, but does contain grease. Plus external sources as above, which is why I'm focused on those.

I suggest cleaning it off and once everything is clean trying to see where the new dirt comes from. Right now it's spread from the source to cover everything, so there's no real way to tell. If you can put it in a workstand then clean off the hub, cogs, belt and everything, then reassemble it and test it you should be able to see whether anything is coming off the bike. I'd rotate the pedals enough to move about 15cm of belt, then run my finger/white cloth on the belt to see whether you can pick up new grease being laid down from one end.

If not, ride it a few metres and check again - visually inspect everything to see if there's new grease appearing. If not, ride it a few hundred metres and check again. Eventually you'll have ridden if every day for a week and if it's still clean the answer is "oil got on the belt from somewhere else". (it might stay a mystery, especially if someone did it deliberately then realised their mistake and doesn't want to own up to it).

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Yes, I initially thought "helpful" children. Only I don't have any grease like that lying around anywhere... –  Adam Eberbach Apr 9 at 0:19
It's hard to be certain from the photo, but it does look like the belt itself is deteriorating. This may be a longshot, but do you park your bike near a big copier or laser printer? Some of these devices are known to give off ozone gas, which can degrade rubber. –  Johnny Apr 9 at 23:11

It has to be somewhere you put your hands to lift the bike.

Check out the wheel rims. They can collect all sorts of grime when you ride in the wet. Some of it will be ground rubber from your brakes, but most is road dirt. Motor vehicles drop oil and grease, and lots of rubber on the road.

If you find that is the cause, the solution is to clean them after riding in wet weather.

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