converting wheel to 126

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Sharky

Guru
Location
Kent
If you shorten the hub by only adjusting one side, i think the wheel would not be central and the tyre might be rubbing on the chainstays.

Might also have problems with the brake not being central.

However, I ran a steel track frame which would have been 120. With a 5 speed rear which must have been 126. It was tight but the frame had enough flex to make it work.​
 

Ajax Bay

Guru
Location
East Devon
[QUOTE 4997918, member: 9609"]I have an older bike with 126mm between the rear dropouts.
For a while I have wanted a spare rear just for emergencies
I have found two rear wheels in a skip the night . . . 130mm dropouts, 8 speed as opposed to my 7 speed.
So to my question, can I convert these so as they fit without bending my frame ?
Is it possible to get a spacer for the freehub so as a 7 speed cassette will fit onto an 8 speed freehub ?
In the picture you can see a chrome coloured washer/spacer between the locking nut and the cone that is 5mm wide; could I simply replace that with a 1mm washer then grind 4mm off the threaded axle ? thus giving me a 126mm wheel.[/QUOTE]
IMO it'd be worth trying to discover if there was a functional reason for the wheels being skipped (as opposed to just surplus to requirement).
From the image these are low grade wheels so the effort to convert them to 126mm OLN (which you need to keep because your wheels in use are 126 (these are just to have a spare)) is probably disproportionate.
Yes, you can get a spacer to allow a 7sp cassette to 'fit' onto an 8sp freehub.
But if you replace the 5mm spacer nut on the axle with a 1mm one, that will shift the centre line of the wheel rim (as @Sharky has said) and when you try to remediate that by redishing, the extreme spoke angles will mean the wheel is unacceptably weak.
If your frame is steel, I reckon @User 's advice is best. If I were you I'd find a 126mm freewheel wheel second or third hand, which would be good enough to serve as a spare.
 

raleighnut

Legendary Member
[QUOTE 4998199, member: 9609"]I am not for one moment thinking of redishing the rim. the wheel would still remain in the centre of the axle, i would trim 2mm of each side and move the hub over 2mm to the side the 5 mm washer is currently on. and replace the 5mm washer with a 1mm one.

I can't imagine it being a disproportionate amount of effort for having a spare wheel - take hub to bits shorten threaded axle by 4mm rebuild using a 1mm washer instead of 5mm one. (10 minutes longer than a standard dissemble regrease and rebuild) and fit a £1.99 spacer. I have a spare tyre and spare 7 speed cassette

I have been trying to source a 126 wheel for ages without luck, and to buy the hub separately and then get a wheel built around it is stupidly expensive for something that may never be used.

The rims were in a skip after a house clearance when the previous owner had done a moonlight flit, so no hope of finding the reason why - in any case what could you learn that can't be observed. they're true, spokes all look good, good sidewall thickness, good smooth bearings and the freehubs sound and feel good. And the 8 speed cassettes look hardly worn (although that is often difficult to tell visually)

Just don't like the idea of forcing the dropouts apart, even by as little as 4mm. they should spring back into place when the original wheel is fitted but I still don't like that idea at all. Also if we are worrying about the rim not being exactly central, why do you assume prising the dropouts apart would be an equal 2mm on each side.[/QUOTE]
It would be easy to replace the spacers by thinner ones, the difficult part is shortening the axle unless you have access to a proper tool room grinder.
I for one wouldn't attempt this on a normal (DIY) 6" bench grinder, for one the grit will probably be too coarse and the tool rests are often very flimsy which makes precision work very difficult.
 
Your frame is steel? If so you should find it will flex to accommodate 130mm hubs. It will take a bit of wiggling but it should work.
A spacer will enable you to put a 7speed cassette on the 8 speed freehub.
I've done this on an old Rotrax from the 50's. It just springs apart, OK, a bit more effort to get the wheel in and out but it was fine for thousands of miles and loaded touring.
 

Ajax Bay

Guru
Location
East Devon
[QUOTE 4998199, member: 9609"]I am not for one moment thinking of redishing the rim. the wheel would still remain in the centre of the axle, i would trim 2mm of each side and move the hub over 2mm to the side the 5 mm washer is currently on. and replace the 5mm washer with a 1mm one.[/QUOTE]
Have a think about this. The wheel centre line needs to stay on the centre point of the distance between the two lock nuts. Replacement of the 5mm spacer with a 1mm spacer would shift that point 2mm. Having said that, as a spare, the bike would ride OK provided you have clearance to the chainstay/mudguard. (I have ridden several 1000km with a wheel in this condition (my lack of understanding bitd).)
I would cold set it permanently.
I've pointed out that the OP has a perfectly good wheel with a 126mm OLN. A spare is sought.
 

Ajax Bay

Guru
Location
East Devon
You'd need to take 2mm off each end of the axle (well, or 4mm off one end and turn it through) but that will not affect the centering. You would need to do that so the axle doesn't stick out beyond the dropouts and make the QR non-functional. You might be better off (engineering-wise not cost) buying a new 126mm axle rather than grinding it down (though perhaps that bit is part of the (your) fun?).
Currently your rim/tyre centre is 63mm from each dropout. Swapping out the 5mm for a 1mm spacer on the non-drive (left) side will mean the rim/tyre centre is 65mm from the right dropout and 61mm from the left dropout (assumes no redishing). The spare wheel rim/tyre centre will be 2mm left of where it is now (ie with your current wheel). You're currently really close on the right side (the "gear side") - this doctored spare wheel will 'move' the tyre 2mm away from that side. Depends what clearance you have on the left side currently. If currently 3mm, you might be OK.
The offset will be noticeable but would be ridable 9conditional on the clearance discussed above). Tyres will wear slightly faster, perhaps.
 

Ajax Bay

Guru
Location
East Devon
[QUOTE 4998425, member: 9609"]my current rear tyre only gives me 5mm on each side.[/QUOTE]
You'll be fine, then. Skewing the wheel 2mm over as you say would be 0.33 degrees. Personally, provided you have clearance (which you have), I'd keep the wheel straight and offset 2mm, being used as a spare. Not noticeable when riding.
 

chriscross1966

Über Member
Location
Swindon
Cheap Sunrace: http://www.ebay.co.uk/itm/SUNRACE-B...994212&hash=item4d1b3e319e:g:sI4AAOSwoudW3n7Z

Expensive but gorgeous Regina: http://www.ebay.co.uk/itm/Regina-Ex...085343?hash=item36216de99f:g:r44AAOSwjPdZz4Um

Cheap Shimano (procreate that Sunrace then) http://www.ebay.co.uk/itm/Shimano-M...631885&hash=item3af45d0d46:g:IsgAAOSwhGlZmAxr

Alternately depending on the make of your hub it might be possible to pick up the components to make something more useful by buying something no-one wants that happens to have them... I've just done this so that I can convert a set of beautiful but pointless Campagnolo Record High-flange hubs into something I can use for a ridiculous custom Brompton I am building, and it's going to cost me a tenner... at the end of which I will have a spare Campy hub in a perfectly normal size that I might well be able to shift on eBay for the tenner the thing doesn't even owe me...
 

Nigelnightmare

Über Member
If you reduce each side by 2mm that will keep it the rim centred.

Then remove the free hub and replace with a 7 speed one and either shorten or replace the spindle and possibly the skewer as well.
It's a bit more messing around but when it's done you'll have an easily fitted spare wheel.
 

Ajax Bay

Guru
Location
East Devon
If you reduce each side by 2mm that will keep it the rim centred.
It would good to understand what you mean by this. The spacer has to be removed from the left side. The freehub cannot be moved closer to the right drop out (or the small sprocket / chain on it will likely foul the chainstay)
 

Ajax Bay

Guru
Location
East Devon
[QUOTE 5003890, member: 9609"]the cassette is thinner so the whole wheel can move over to the right,.[/QUOTE]
With a 7 speed freehub, this could work: fitting a 7 speed cassette on an 8/9/10 speed freehub needs a 4.5mm spacer so maybe that's the 4mm you (the OP) needs.
 
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