Can anyone suggest where in/around Edinburgh I might get my Shimano Nexus 7 speed hub repaired? It died going to work this morning (something went ping...or was it crack...or scrunch...) and there is now no drive in any gear. All externals (cable, shifter etc) are connected and OK, it's deffo an internals issue.
CityCyclingEdinburgh Forum » Questions/Support/Help
Dead shimano hub gear repair
(23 posts)- Started 9 years ago by Its_Me_Knees
- Latest reply from I were right about that saddle
- This topic is
not resolved
-
Posted 9 years ago #
-
@Its_Me_Knees
Oh dear. Sheldon Brown seems to be reading the last rights; "The internal mechanism of these hubs is complicated, and the usual repair is to replace it in its entirety."
It also looks like they've changed the dimensions over time, so that could well mean building a new hub into a new wheel. You can get a hub plus furniture for about £140...plus wheel build plus fitting....
Posted 9 years ago # -
First stop Bicycleworks.
Posted 9 years ago # -
@IWRATS: Yep....not looking good, is it? I've had the bike around 5 years now, but it only accounts for half my commuted miles. It was serviced locally about 18 months ago but I wasn't v impressed when they gleefully told me that they'd used car transmission oil rather than the (expensive) Shimano stuff prior to reassembling. It also gained a ratchety sound that it previously never had and I'm left thinking the service did more to shorten the life of the hub than lengthen it...
@Kaputnik: noted.
Posted 9 years ago # -
@Its_Me_knees
Oh dear. Shimano hub gears are not oil-tight. They are greased because otherwise the oil...falls out through the grease seal. That is why your hub has died - it has been assassinated.
Posted 9 years ago # -
<Murder enquiry commences...> :-(
Posted 9 years ago # -
oof. are you going to name and shame?
Posted 9 years ago # -
@SRD Best not to... Any bike servicers who read this forum (and this thread) will recognise if the 'transmission oil' trick is a shortcut they use...and will hopefully not use it any more.
Posted 9 years ago # -
If they'll take one shortcut, they'll surely take another. I for one would like to know who to avoid. Please name 'em
Posted 9 years ago # -
I think we need to be a bit careful here before naming anyone...
My understanding is that the oil bath service is the correct method for servicing an 8-speed Alfine Hub, so it may well be valid for Nexus too. Here, for example, is the oil on Amazon, and here it is at the bottom of the parts list for an Alfine Hub (
The instructions on the bottle show to dunk the hub for a period and then leave it to drain before re-installing it. Presumably this is to wash out any contamination from the hub, but also reflects that fact that the hub isn't designed to run in an oil bath, so it will leak oil if put back too 'wet'.
There's lots of stuff online about using other oil (or transmission fluid), and the volume of this drowns out the official Shimano guidance.
The 11-speed Alfine hub is different. It has a permanent oil-bath (like a Rohloff), and this can be maintained on the bike using (another) Shimano kit via an oil port on the hub shell.
hubstripping is worth a read if you enjoy the intricate engineering of an IGH. So much more satisfying than a derailleur in my view. It's like watch-making.
Posted 9 years ago # -
The oil bath is a sort of service rather than a repair.
A very excellent mechanic used to repair my nexus 8, a much worse hub gear than the nexus 7. Due to the thin lithium grease inside the 8 whcih could not cope with water ingress. Alfine 8 and Alfine 11 better than nexus 8. Actual hub double sealed. The nexus 7 better than the 8 as It used thick grease rather than the lithium stuff and the thick grease copes better with water ingress.
This very excellent mechanic was subsequently not allowed to repair the nexus 8 by his employer and this oil bath malarkey became the only route. That is when I switched to sturmey 3 spd
Posted 9 years ago # -
Shimano tech docs for Nexus 7 don't appear to cover work on the internals, which I suspect is a broad hint that you're on your own if you do go there. Very hard for a mechanic to assess the risk of attempting repair - I can understand a workshop manager being very wary of opening a unit with an unknown history.
Posted 9 years ago # -
Ah. General document specifies Shimano Nexus grease and strongly suggests not taking the planet gears apart.
Posted 9 years ago # -
In a surprising manifestation of the n+1 affliction, it looks like it could be cheaper to buy a second-hand example of my affected bike, than to buy a new hub and have it fitted...
Posted 9 years ago # -
@Its_Me_Knees
Tis often thus, bikes being mass produced by people on Chinese/Malaysian/Taiwanese wages and repaired by artisans on UK wages.
Thing is of course you've no idea what's in this hub casing - oil and rust or grease and steel?
Posted 9 years ago # -
In the excellent mechanic's workshop there would often be a number of spare bits of broken nexus 8 hubs when he was fixing my hub gears. The party line was of course that there was nothing wrong with the product but the Alfine range came in very quickly to replace the nexus 8
Posted 9 years ago # -
I happened to pick up an (apparently) working Nexus 7 as an interesting objet to play with at the Bike Station. For a fiver it seemed like offering well more than £5 of fun taking it apart and looking inside and even seeing if I could make it work.
I know we have a specific grease there (here) but wondered if any of our resident greaseologists had any further thoughts on how to lubricate such a hub without proprietary lubricants. It's £13 for a tube of the stuff so maybe best to just buy some and see!
Seems a lot of online fora recommend automatic gearbox fluid but also making sure to heavily grease the seals to keep the fluid from all leaking out. An example set of instructions is here, which involves a total degreasing of the hub before immersing in ATF oil and then heavily greasing. It would appear that the logic is that "here in Minnesota" it's too cold for Japanese grease and so oil is better for the hub. I imagine that the climate of Edinburgh is somewhat closer to Sakai city.
Posted 7 years ago # -
Was it me? If so, I'd like to think you'd give me a holler in the first instance. If not, then here are my thoughts.
The ATF method is a recognised way of servicing Alfine and Nexus hubs. It is important to thoroughly grease the LH bearing to prevent oil egress, especially disc hubs. I have serviced dozens of hubs this way and never had a complaint. And have serviced many more than once. ATF is a very high-quality lubricant and is more than capable of dealing with the rather low temperature, benign conditions of a hub gear, compared to power steering systems and automatic gear boxes.
If the hub was making a noise post-servicing, it would have been a good idea to return immediately for investigation. The noise would likely have had more to do with reassembly rather than the type of lubrication used.
Posted 7 years ago # -
Sorry, I'm lost. Why would you put ATF fluid in a hub?
Why not just refill with exactly the same grease/oil/fluid/whatever that the manufacturer used in first place?
That way it is working "as designed"
Posted 7 years ago # -
I think the answer is that Shimano charge about the same for a litre of their proprietary lubricant as they do for the entire hub and it seems to basically be the same as ATF. I don't know myself, hence resurrecting the zombiethread, but much googling has suggested it's pretty standard practice.
Posted 7 years ago # -
@kaputnik
I used to use Purple extreme bike lube, but then I just started filling the bottle up with 10W-40 semi-synthetic engine oil, of which I have a litre sitting in the shed. It's one seventh of the price and I can't see any difference in performance. The engine oil might actually be better.
No way is a bike hub a more challenging environment than any part of a motor car, though external gears and chains are obviously more exposed to weather.
Posted 7 years ago # -
@IWRATS and for desert? (Grease?)
Posted 7 years ago # -
@kaputnik
If you must use dessert as a lubricant try tiramisu.
Posted 7 years ago #
Reply
You must log in to post.
posts
