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I live in Finland, and as such the weather right now is pretty cold. Since I rely on my bike for shopping in a rural area, the frequent and complete loss of drive I now suffer at below-freezing temperatures is intolerable. The local bike shop has looked at it twice now, and utterly failed to fix the problem; I don't think they've tried very hard. When kept in a warm place overnight, it works fine, but as little as a quarter of an hour outside is often enough to make it fail again.

My own research so far indicates that I have a roller-clutch freehub (ie. it doesn't tick when coasting), which is in general more prone to failure than the ratchet type. Most of the mechanical fittings on the bike appear to be from basic Shimano ranges; it was an ex-rental. The model number on the hub body is FH-RM30, and the gearing seems to be an Alivio 8-speed at the rear, and a Nexave 3-speed at the front.

I'm keen to replace the freehub with a ratchet unit for reliability and longevity. However, I'm reading suggestions that the two tend to use incompatible interfaces to neighbouring components.

My question is: how much do I need to replace?

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  • I know not the stated question but maybe get a single speed backup bike for winter use. I get you still need to get the main bike reliable.
    – paparazzo
    Commented Jan 21, 2016 at 16:04
  • This isn't exactly a fancy bike to begin with. I think most serious cyclists would call it a beater.
    – Chromatix
    Commented Jan 21, 2016 at 16:26
  • @Chromatix we have a wide range of viewpoints from serious road riders, to touring types, commuters, and those for whom getting the most out of a cheap bike is either necessary or entertaining. Don't worry about the quality of your bike.
    – Chris H
    Commented Jan 21, 2016 at 17:00

2 Answers 2

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At the absolute minimum you should be able to replace just the freehub body. Some Googling should turn up some compatible options.

The plot thickens, this hub seems to use a different freehub style to most other Shimanos. This would work with the majority of clickity hubs, but Sheldon says the silent ones are different.

The freehub body is the dark grey splined part of the hub that turns.

If you remove the axel and bearings you can pop this off with a large allen key, I forget the size, 8 or 10mm.

Getting it all back together can be a pain, the freehub's easy, but the first time you set cup and cone bearings yourself will make you curse.

The next option up, is to replace the hub with one that already has the freehub you want and get someone to relace your wheel.

Then a whole new rear wheel, then a new bike.

These options go from most to least work and least to most cash.

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  • Removing the axle and bearings would seem to require tools I don't have - which is why I asked the bike shop to look into the problem in the first place. Replacing the entire hub does sound like a lot less work. Would I need to replace the gearset as well?
    – Chromatix
    Commented Jan 21, 2016 at 14:58
  • You shouldn't need to change the cassette. Your cheapest option is likely to be another Shimano anyway.
    – alex
    Commented Jan 21, 2016 at 15:05
  • @Chromatix, I've read a bit deeper into this, looks like a new hub is the minimum change. A new wheel might be about the same price as a new hub and labour.
    – alex
    Commented Jan 21, 2016 at 15:25
  • Well, that gives me concrete options to ask the shop about. They do have a proper workshop (which I don't), but I suspect they looked at the complexity of taking the hub apart and decided just to give me back the bike after warming it up so I could get home.
    – Chromatix
    Commented Jan 21, 2016 at 15:27
  • Got it back from the shop today (after an 8 mile walk). This time, they actually opened the hub and cleaned it (which implies they didn't do so the last two times, despite my asking them to). Time will tell whether it actually fixes the problem - the weather is mild right now, so I can't tell the difference.
    – Chromatix
    Commented Jan 30, 2016 at 2:32
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Freehub bodies tend to be hub specific. So the chances of Shimano doing an interchangeable one is remote. Freehub bodies can be significantly expensive when compared to the price of a cheap/moderate wheel - so might be more economical to replace the complete wheel - especially when you factor in not only the cost of the freehub but also the cost of labour to fit.

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  • Replacing the wheel also mean summer/winter wheels are an option (rather than summer winter tyres which I assume the OP is doing given the Finnish winters).
    – Chris H
    Commented Jan 21, 2016 at 16:58
  • True, although the front wheel has a hub dynamo installed. Honestly, I think changing wheels will be just as much hassle as changing tyres anyway.
    – Chromatix
    Commented Jan 21, 2016 at 18:22
  • The bike shop is now looking into the problem for a third time, hopefully more thoroughly than before. Since they said it'd take two days, I suspect they'll be rebuilding the existing wheel around a new hub. Time will tell...
    – Chromatix
    Commented Jan 25, 2016 at 21:20

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