Swapping Freewheel for Freehub?

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maxglide
Posts: 178
Joined: 19 May 2013, 5:35pm

Swapping Freewheel for Freehub?

Postby maxglide » 17 Feb 2019, 1:52pm

Looking at changing the Shimano Tourney 26" 7-speed freewheel on my MTB for a freehub. The bike may be called out for a week long putter around Wales, and I don't fancy the hub shearing off, bombing down the Beacons. Experts say this usually occurs on budget freewheels, which the Tourney certainly is.

Under power, the cassette wobbles oddly, too, which I'm told, is because of defective threading on the hub/cassette. So, there was a problem from the get-go as the bike was bought new.

Is it then, a question of merely taking the whole wheel off and replacing with a say, Deore freehub wheel & cassette, or is more involved, i.e replacing the mech too?

Brucey
Posts: 34821
Joined: 4 Jan 2012, 6:25pm

Re: Swapping Freewheel for Freehub?

Postby Brucey » 17 Feb 2019, 3:00pm

you only have a 'cassette' once you have a freehub. You have a threaded hub and a screw-on freewheel at present. That the sprockets are wobbling about is a pretty good sign that something is wrong with it.

7s freehubs are still supplied on new bikes to this day but shimano has practically abandoned the idea. This means finding a NOS and/or off-brand 7s freehub, or a used one. The alternative to this is using an 8s freehub and fitting a 7s cassette to it with a spacer. This is unappealing for several reasons, not the least of which are concerns about the OLN width of the hub vs your frame and the amount of wheel dish.

Your extant wheel could be 126mm 130mm or 135mm. A deore 8/9s hub will be 135mm. You can also buy 130mm 'road' 8/9/10s hubs or modify the deore to 130mm. A 7s 135mm wheel has very little dishing on it and is inherently strong. A 130mm 8s wheel more sort of isn't, and if you try to make a 126mm 8s wheel it is liable to be almost completely hopeless.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

mattsccm
Posts: 2637
Joined: 28 Nov 2009, 9:44pm

Re: Swapping Freewheel for Freehub?

Postby mattsccm » 17 Feb 2019, 3:34pm

He is right but to put it simply, you need a different hub.
Bunging another wheel in will be easier and cheaper I reckon.
All above worth knowing or look here and then other related pages

https://www.sheldonbrown.com/free-k7.html

zenitb
Posts: 262
Joined: 7 Aug 2018, 9:59pm
Contact:

Re: Swapping Freewheel for Freehub?

Postby zenitb » 17 Feb 2019, 11:00pm

maxglide wrote:Looking at changing the Shimano Tourney 26" 7-speed freewheel on my MTB for a freehub. The bike may be called out for a week long putter around Wales, and I don't fancy the hub shearing off, bombing down the Beacons. Experts say this usually occurs on budget freewheels, which the Tourney certainly is.

Under power, the cassette wobbles oddly, too, which I'm told, is because of defective threading on the hub/cassette. So, there was a problem from the get-go as the bike was bought new.

Is it then, a question of merely taking the whole wheel off and replacing with a say, Deore freehub wheel & cassette, or is more involved, i.e replacing the mech too?

Key question Max-
if you remove the rear wheel and measure the distance between the dropouts is the gap 135mm?

If it is 135mm then you are good to go. 135mm is still a standard modern size. Get a brand new 26" cassette wheel, 7 speed cassette and spacer and you are good to go. (also need freewheel/freehub removal tools and chainwhip or get bikeshop to swap it for you)

If it is not 135mm then its trickier... Report back here and I am sure suitable advice will be given :-)

maxglide
Posts: 178
Joined: 19 May 2013, 5:35pm

Re: Swapping Freewheel for Freehub?

Postby maxglide » 18 Feb 2019, 3:40am

@ zenitb

The width between the dropouts was the first thing that occurred to me, but I didn't mention it in the post. I did assume it was a standard, but an old one by now as mentioned by Brucey. I know it's a screw-on freewheel, I was using 'cassette' as a convenience to refer to the stack of sprockets. I'll measure the gap - hope it's 135mm...