Welding cogs
 

Yeah... so half a week ago i made a thread questioning if I stripped my cog/hub. I most definitely did. Luckily my hub had 2 fixed sides... so I just flipped it and stupidly put my cheap cog back on my hub.

Last night I was riding a bit fast and had to swerve and slowdown to avoid a road block (I didn't have my light, and a student organization blocked off the road in order to practice pushing a bobsled/luge/death trap up the streets) and as I mashed my legs down to skid, I felt the cranks "slip"-- just like they did when I stripped the other side. I'm 90% sure I stripped the 2nd side of the hub.

I'm a poor student but a student with access to facilities. I'm not too interested in paying more money and investing more time into having my back wheel rebuilt (although I got it built by a local guy... I doubt he'll take pity and do it for free-- but he might not charge labor..)

Would it be possible to MIG or ARC weld the cog to the hub? Both sides are stripped/useless-- I could probably salvage the lock ring and just weld the thing like there's no tomorrow.... but would it actually hold? I've welded chairs and stools (like 3 years ago) and they seemed to hold up pretty well. Anyone have any experience with this?

Or are my fixed gear dreams over?

If the hub is alumium, how you gonna weld the steel cog to it?

old campy alloy cog?!

if he has a cheap enough cog it might be aluminum. or if you can find an al. cog to replace it, would be cheaper than building the wheel.

edit
this is the only al. cog i can find.
http://cgi.ebay.com/EURO-ASIA-ALLOY-...QQcmdZViewItem

He should just buy a new hub and a good cog.

of course you could weld an aluminium cog to the hub,
but it wouldn't last that long. i mean, an aluminium cog will
get worn out fairly quick. i guess you could always weld another
cog on the other side, but then you're done.

JB weld it

amen

If you had access to a mill and cut key grooves into the cog and hub, it would probably work. Welding steel to AL will be tuff.

okay, so, i've had that happen to me - "i'm pretty sure i just stripped my shiznit" - but you should definitely take it apart, clean and check the threads. it could slide without stripping, and you should check.

and then you should throw that cheap cog away and get a dura ace cog, cause $20 isn't too much to spend to be more confident that you won't eff up your hub.

capisce?

You can't really weld ferrous and non-ferrous metals together. At least not for things that have to be structurally sound. You'd be better off trying to braze them together, but you'll probably just melt the aluminum.

check the threads again, and learn to install your cog and lockring correctly.

Speaking of welding, is there any way to weld or lock my Campy-compatible freehub body on my old Spinergy wheel?
BTW, the Fixxer thing from Surly only works with Shimano freehubs.

Pull off the freewheel part and braze it together or LB weld. All kinds of ghetto but it could work.

If you're handy with a dremel, or have access to a milling machine, you could try cutting grooves for a 3-speed cog.

Secure it with the lockring, and you should be good to go.

well, you've probably seen this but just in case:

http://www.fixedgeargallery.com/arti...anula/freehub/

also crimson karter claims to have just drilled a hole in a freehub and stuck an old key in there. i'm not sure of any of the specifics beyond that, but you might want to pm him.

I did it with a cheap alex rim with quando hub. stripped the sucker bad. Took Jb weld and coated the threads on the hub and spun the cog on. Then put a coat of jb weld around the outside of the cog where it meets the hub facing out. let it cure for a day or 2 then ride. Mine held up for about a month until my new wheelset came in then I took out the axle, cone nuts, ect. for future emergency use if needed and threw the wheel away

I'm actually thinking of doing this for a polo bike. Thanks for the link.

I'm finding it hard to believe a thread can be stripped by pedalling backwards. Were you using a lockring? If not, is it not possible your cog just unthreaded itself?

Guys such as Chris Hoy put about 550 watts through their pedals from a standing start and never strip cogs. Locking a wheel with your legs needs only about half that wattage.

An old aluminum Dura Ace or Zeus cog might possibly strip - I've seen a tooth ripped off an aluminum cog.