Bicycle Mechanics - Replace suspension fork with a rigid fork

Is it ok to replace a suspension fork on my mountain bike with a rigid one? I was given an older GT aluminum mountain bike with a worn Manitou 3 suspension fork. I would like to spend as little as possible to get it going so I was thinking of replacing the suspension fork with a cheap rigid one. Would this be ok? If so, does the rigid fork need to have any rake or is a straight one ok. I am thinking I would need some rake even though the current suspension fork is just straight. Anything else I should consider?

Thanks

Without suspension the new fork may be quite a bit shorter between the axle and crown. This will mess up the bike geometry and could leave your pedals very close to the ground.

Those actually came from the factory with rigid forks installed and the Manitou in a box.
Many shops still have a few of the original forks laying around, bologna forks....
http://forums.mtbr.com/showthread.php?t=474531

Without suspension the new fork may be quite a bit shorter between the axle and crown. This will mess up the bike geometry and could leave your pedals very close to the ground.

no, no, no... The Manitou 3 is such a short fork by today's standards that a stock Surly fork would likely raise the front end.
Couldn't even run a 26x2.2 in one of those things...

If you look at the rigid forks available, many will say that they are "suspension corrected." This means that the end result of installing the fork will put the bike at about the same place as it would be with the suspension fork compressed slightly.

If you look at your current suspension fork, you'll see that the dropouts are forward of the legs on the fork which gives you some rake. It would be impossible to have curved suspension fork legs so the offset method is used. The end result is the same.

I will also add a shameless plug for my soon-to-be unneeded Surly 1x1 fork (http://www.speedgoat.com/product.asp?part=45797&cat=34&brand=245). It's the V-brake only version and the steerer tube is cut to about 8.5" so if you have a medium or smaller frame it could work for you. I'm sure we could work out a cheap deal if you were interested. It's in very good shape but is being replaced by a fork with a disc mount.