Im trying to convert an old stumpjumper to a fixed gear and the wheel sizes are 26x1.50. Where can I find a fixed hub that will fit or what can I do to make it work?

Buy a new wheel?

Where can you find a fixed hub for a mtb? I've done a few of these. One I got from Craigslist, one from eBay, and one from a bike shop. I'd think you can find one at one of those places.

your mother was a hamster and your father smelt of elderberries

You'll either need to buy a whole-new 26" wheel with a fixed hub, or rebuild your existing rear wheel with one. The latter is what I did. Does your Stumpjumper have horizontal dropouts?

if the rear wheel hub have a disc brake mount can't he just flip the wheel and bolt a cog like this (https://velosolo.co.uk/shopdisc.html)?

also: https://velosolo.co.uk/faq.html#c2

"Which (drilled cog) hub/set-up is best for my mountain bike ?"

"First be sure you can run a fixed wheel on your frame. See above questions.

Yes? Great - the route to fixed is easy. The rear spacing on virtually all mountain bikes is 135 mm. The best set up is a normal rear cassette hub with 6 bolt disc mount - you probably have one of these on your mountain bike right now.

By mounting a drilled cog on the disc mount and a normal singlespeed cog and spacers on the freehub side you have a flip/flop fixed/free wheel (see pic below). As simple as that, no alterations are necessary and the wheel can be used with gears again simply by removing the singlespeed cog and mounting a cassette.

Using a cassette wheel with a single cog and spacers allows the chainline on the freehub side to be adjusted to match the fixed side perfectly. Thus when flip/flopping the wheel your chainline stays spot on. A cog mounted on the disc side will in most cases give a near perfect chainline with the outer front ring.

Or use a standard mountain-bike singlespeed (ie screw on freewheel) 6 bolt disc hub."

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If it's a M2 Stumpy from 95-98ish the magic gears are 34-17 and 44-16. Work perfectly.

If it's a freehub, uh, hub (pretty sure it is) then you can use the surly fixxer. But because of the vertical dropouts, you'll still have to play around with cogs and rings to find the "magic" gear to keep the chain tight.

If you want more available gear ratios, you'd have to use a hub with an eccentric axle like the White brothers ENO hub. At $135 for just the hub, you're losing a lot of the appeal of a fixed conversion vs buying a dedicated single speed frame with horizontal dropouts/track ends.

it does have horizontal dropouts. im planning on rebuilding the with a new hub. but where can I find the hub?

Surly makes Mtn fixed gear hubs. Surly is owned and distributed by QBP, a major bicycle parts distributor. Ask at a shop if they can order a hub or build a wheel for you; find a source online that can sell you the hub or a built wheel.

Alternately, you could find any disc compatible rear wheel and use one of those fixed cogs which bolts onto where the disk would otherwise be.

all mountain bikes made after the mid-90s maybe.. a stump jumper with horizontal drops i likely from the 80s though

so it's 130.

From what I've gathered here, surly hubs suck.

What do you think the spacing would be on my stumpjumper?

Why don't you measure it and tell us?

It could be 126 or 128 as well (i have mtbs with both of those).. only way to find out for sure is to measure

Okay I'll measure it today. Thanks guys

This Sheldon pic might help...

Wait, what's that stick thingy with the numbers on it?