ahead stem on threaded steerer.

The thread steerer on my Manitos is about 2.5 inches too long to use with a threaded headset, but would be the ideal length for an ahead stem.

Is it safe to use a ahead stem to clamp the steer on the threads (I'd probably use a hope head doctor expander rather than a star nut), or is this ravings of a madman?

I was looking into something similar and the consensus is: Don't! There are people that have done it but it is not advisable as the threaded part is weakened by the threads and ahead stem compression might collapse it. Also you will royally f***k the clamping surface of the stem (not enough surface on the threaded part to provide enough clamping force = more clamping force required = possible collapse of the steering tube). If your fork is a Manitou 1,2,3,4 or Mach5 you can easily swap out the crown-steering tube assembly. Or you can cut the threads lower and run a threaded setup after you shorten the steering tube to the appropriate length.
I my case I waited until a suitable size steering-tube crown assembly popped-up (Manitou 4 fork).

Re:

From what I've heard, it probably isn't the best idea because the threaded section is not designed for the sort of forces that an ahead stem can put on it. The steerer could crack or shear off at the threads due to stress risers.

Re:

My matey has an original syncros cattlehead running on a threaded steerer of some Mag 21`s. It`s a 1 1/8" headset and he`s been riding it hard for three years now & his face is still intact.
I`m not recommending it but each set up will be different, some steerers increase in diameter a bit below the thread which would make the stem wobbly as hell if the stem clamps over this point. His setup is rock solid but I bet it`s rough inside the stem now. I think it boils down to one question.

Do you gamble?

Thanks for the responses, looks like the jury is definitely in the no camp. Will go for the rigid forks until I can get a correct length steerer on the the Manitous.

Re:

I'd go with the 'no' option too if for no other reason than, as said previously, it's a quick fix with Mani's by swapping the steerer, or extending the threads.

Reviving an old thread rather than beginning a new one.

I've had this less-than-ideal setup on my single speed since I built it up. It's only used on the road, so not subjected to as much as an ATB usually would be. I am just about to (finally) get the frame and fork powdercoated and it has made me wonder about this. The fork feels really good with this frame and the steerer length is perfect, so I am inclined to keep the setup as it is, rather than the time and expense of trying to find an alternative, equally nice fork.

Assuming I decide to keep this setup, any recommendations for mitigating any damage (to the bike, not to me if it failed). Previously, I just had some electrical tape around the threads to reduce any marking to the inside of the ahead stem (barely marked, so worked quite well) but would there be a better alternative, such as trying to fill the threads with epoxy putty?

Why not run a threaded setup but with a stack of ahead spacers between the two headset locknuts?

It would be more wise to have a sleeve inside the steerer to prevent the threaded portion from collapsing or sheering off.

hamster said:

Why not run a threaded setup but with a stack of ahead spacers between the two headset locknuts?

Click to expand...

It would be a stack of spacers about 50mm high and I'd then have to use an ahead adaptor to use the existing stem, so it would add height and weight to the front of the bike.