J_J

Hasn't happened to me but I am curious as to what the fix would be if the bolt was completely rounded off....say if it was tightened waaaay too tight and forcing it open just rounded off the bolt completely. What would a shop do if they had a customer bring in a bike with this problem?

Stacey

What head style are you talking about? That would determine my course of action.

capwater

If the bolt head is not recessed you can cut a slot in it and use a flathead screwdriver on it. If there is enough "meat" then you can go with a visegrip.

cuda2k

Another option would be to use JB Weld and an old allen key wrench. Use the JB Weld to securely attach the old allen key into the rounded out hole and then remove.

clancy98

im gonna saye vise-grips too

operator

Interesting solution, *jots down in notebook*.

idcruiserman

I doubt JB Weld would work in that case. It wouldn't handle the torque.

the royal 'we'

If you want to spend a bit of money but never have that problem again, invest in a set of the Craftsman bolt extracters, designed entirely for the purpose of removing stuck, rounded off nuts and bolts. It's around $25 for a set of 'em, but IMO they're worth it for the amount of time and frustration saved. And not that I condone such actions, but you *could* save the receipt and return 'em afterwards.

Edit: Aww, dammit, didn't think about allen bolts... Though, as long as the bolt head has enough sticking up to get a grip on it, those extractor thingies will still work.

DannoXYZ 

Just use a drill-bit that's slightly larger than 8mm. Drill out the stripped allen-key hole. As soon as you get as deep as the shank of the bolt, the head will fall off. The remainder of the bolt should come out by hand easily since the tension is removed.

the royal 'we'

If you can keep the drill bit centered on a regular hex bolt, the drill trick will work on that too. Just make sure you have a sharp bit, some of those bolts can be a b*tch to drill through.

Svr

When time is money (and even when it isn't), that is the absolute best way to go.

jimmay

Yep, that's what I did in my hypothetical situation!

Cadfael

Not sure what a vicegrip is... but I have done this very same job, not only with the seatpost bolts, but wheel hub bolts using a small pair of Stillsons (think the US call them Pipe Wrenches). This of course assumes there is enough to get a bite on them. The bolt is kiffed anyway, so it does not matter if the head is chewed to bits, as long as it does come out to replace it.

Stacey

Visegrips...

Retro Grouch 

My first trick is always to try using a brand new allen wrench. Most of the time that'll do the trick. Then throw your old allen wrench away because it's rounding out bolts.

Cadfael

Thanks for that... we call these Mole Grips in the UK.

Don't ask me why.

Cadfael

A further question...

Would it not be best to replace allen bolts with... a lets say a dome head, to a cap head for this very reason? I know it won't work in all cases, but in most cases this will not only give you something to bite onto if the worst happens... but will also sometimes need a larger allen key that is a bit more robust.

As a for instance... I replaced the 3mm dome heads on my bottle cage to 4mm cap heads, same thread, just a different allen size.. Not for this reason I hasten to add, the old ones had rusted and I replaced them stainless steel ones from work. Okay a bottle cage is not all that important, but would it work in other areas?

Daveonabike

valve grinding compound in the allen hole, insert allen key, works every time. I am a auto mechanic and only work on german cars, I know rounded allen bolts

robo

I won't, but i'm glad i'm not an English mole..

Cadfael

Jasper Carrot is happy you is not an English mole... otherwise he would have blown your head off.

ianjk

I'll second the vice grips, expecially if the bolt is hosed already.

I've actually welded an old 1 1/2" washer to a stripped head on an allen bolt and used a screwdriver to turn it....

It was on a junk stem for a chopper though, thought it looked cool

theopowers

I didn't need a pic of visegrips, but I have no idea what this stuff is.

Stacey

Google is your friend.

DannoXYZ 

Another tip is to grind off 0.5mm from the ends of your allen-keys. This removes the rounded end that can slip. Instead, you'll nice sharp corners on your tool to really grip those bolt heads.

tellyho

I LOVE the grinding compound solution! I've used the drill-the-head-off solution with success on cleat bolts.