Anybody know of a quick & easy hack to lock out a basic front suspension?

More details: My spouse has an older Trek 7200 Multitrack, and is looking for something a bit more nimble. As a larger rider, I'm not sure they benefit much from the front suspension that the bike has...it's at least 1/2 compressed standing still and there doesn't look like there is any preload adjustment or anything like that. I was hoping I could figure out a quick way to lock it out to see if they preferred the suspension or would be happy with a rigid fork. This is a hack that would only need to work well for at most ~10 miles, just as a way of trying things out once.

Appreciate any ideas. Thanks!

A locked out fork doesn't compress. This will yield the most relaxed steering geometry. If your spouse wants more nimble steering, that will be counterproductive

shaft collars for a more permanent solution, a hose clamp would probably work in a pinch

Good point...I was thinking about it just in terms of height. It had not occurred to me that there is an effective geometry change as the fork compresses.

As a fork compresses, the head angle effectively steepens. If you wanted the most nimble handling you would have to figure out how to lock the fork in a fully compressed condition.

It's not going to help the bike be more nimble, but if you want to stop it from going through half it's travel while standing still, maybe you could see if your LBS might have an elastomer sitting around that could be cut and inserted on top of the springs (assuming it's springs) to take up slack.

You could consider a dowel rod inside one of the fork stanchions. Take out the spring and replace it with the largest diameter dowel rod that will fit, cut to the correct length. If the top of the stanchion has a thread-on top cap (as most inexpensive ones do), this should be pretty easy to do. Size the dowel rod about a half inch longer than you think you need and slowly shave it down until you can thread the top cap most of the way on without bottoming the cap out and having the dowel rod just a hair too short.

Second note: I just read that you're considering replacing the fork with a rigid one, if she likes the feel. In order to keep the same geometry as the locked-out fork, you'd need to buy a suspension-corrected fork (with an axle-to-crown distance that approximates the length of an uncompressed suspension fork). Or, if you think you might want a standard (shorter) rigid fork, you could just ride up and the down the street without the spring in the fork at all. This would basically ensure it's at full compression all the time (and would really steepen the head tube angle).

This is not really a "safe" way to ride, but it could be useful just for testing how the bike handles with a standard (shorter) fork.

You may find that she likes the feel of the fork locked enough to just run it like that. It does make a heckuva difference (locked vs. unlocked). Sure, it's still pretty heavy up front compared with a rigid fork, but the bike would continue to handle and ride about the same (minus the squish).

This sounds much better than a hose clamp that is likely to scratch the chromed plating if it moves and then lead to rust or the spring leaking out.

Why not just pick up a used rigid fork? I found one for my bike for $16 and the swap was easy and the weight reduction made a much more fun riding experience.