Hay, has anyone replaced a Trek marlin (G2 geometry)suspension fork with a Surly Ogre fork. Unfortunately, I want a new 29'er but don't want suspension forks. Because of the G2 geometry, it sounds like I would ruin the bike by putting a non G2 fork on it. Has anyone proved this to be false? Thanks in advance for your responses.

It would help to know what fork is currently on the bike. G2 just means it has a 51mm offset, which most modern suspension forks have. If you want to switch to a rigid fork, you should try to match the (sagged) axle to crown height of your current fork and the rake. To get the sagged axle to crown height, you would normally subtract about 20 to 25% of the fork travel from the unsagged height. For example, if your axle to crown height is 500mm and the fork has 100mm of travel the sagged axle to crown will be in the 475 to 480mm range.

The Surly Ogre fork only has a 43mm offset. The Surly ECR is a bit closer at 47mm. They appear to have several different 29er forks with differing axle to crown heights and offsets, so you may be able to find something close.

[QUOTE=dsaul;19389048]It would help to know what fork is currently on the bike.

The current fork on the bike is, SR Suntour M-3030, coil spring, preload, 75mm travel. If I could justify the Marlin 7, with the rock shock fork, I would be half way to a Surly Ogre, which would have my fork. Then again it would have disk brakes, which I don't believe I need any more than suspension forks. I like the simplicity of a bicycle (a simple one that is) and the ruggedness of a Mountain bike.

People say 10% sag, so measure the blade length

by having someone do that crown race seat to axle center distance while you are on it.

your weight pushing down.. 50mm offset? confirm, then take that data shopping..

Thanks for the info. Can't do the measurements as I don't own the bike yet. Maybe I should just buy the one with lock out forks and the disk brakes and adapt.

So I talked with the bike mechanic today. It was very discouraging. Short of building from scratch, he made it sound like it couldn't be done. So I came home and looked at the web some more and I think I found it. MKM 35 Rigid Carbon MTB Fork. Except It is sold out. I hope it will work and they get more in,

Check White Brothers Rock Solid Carbon Fork or Origin 8 Black Ops. I installed the Origin 8 on a Giant hybrid some 5-6 years ago in place of a suspension fork.

If your looking to replace parts on a bike you haven't even bought yet, you looking at the wrong bike.

As you are finding out, the bike you are looking at has a proprietary design (G2), getting a bike which has a standard design & rigid forks out the box will be a lot cheaper and more importantly easier than the way you are looking to do it currently.