FM1002 - 160 or 170mm fork?

[FullCarbonAlchemist]

I’ve been running my FM1002 with a 170mm fork since I built it up in the spring, and I know several others here are too. Who’s running it at 160? Has anyone tried both?

I’m about to swap forks on mine and the Fox 38 I want to put on is currently set to 160 (I also have a 170 air shaft for it) so I’ve been thinking about this a lot. I’m also thinking about building a FM1003 next so once I have that bike with a 180 fork, maybe keeping my AM bike at 170 is a little redundant.

This debate has come up a few times so I thought I’d make a thread specifically to discuss it: let’s hear your thoughts!

[Swolie74]

I’ve been running my FM1002 with a 170mm fork since I built it up in the spring, and I know several others here are too. Who’s running it at 160? Has anyone tried both?

I’m about to swap forks on mine and the Fox 38 I want to put on is currently set to 160 (I also have a 170 air shaft for it) so I’ve been thinking about this a lot. I’m also thinking about building a FM1003 next so once I have that bike with a 180 fork, maybe keeping my AM bike at 170 is a little redundant.

This debate has come up a few times so I thought I’d make a thread specifically to discuss it: let’s hear your thoughts!

While I don't currently have this frame set, I would say that the geometry doesn't lend itself as well to over forking that the 1001 does...

[casual_build]

I haven't tried a 160mm fork, but the 170mm fork seems to perform well while climbing. The geo give a ~64.5 Degree head angle with a 160mm fork. I wanted something slacker and more confidence inspiring so I over forked 10mm. I think its right for me.

I am also curious if anyone has tried both.

While I don't currently have this frame set, I would say that the geometry doesn't lend itself as well to over forking that the 1001 does...

What do you mean? Are you talking about the bend in the frame?

[Swolie74]

I haven't tried a 160mm fork, but the 170mm fork seems to perform well while climbing. The geo give a ~64.5 Degree head angle with a 160mm fork. I wanted something slacker and more confidence inspiring so I over forked 10mm. I think its right for me.

I am also curious if anyone has tried both.

What do you mean? Are you talking about the bend in the frame?

the 1002 is currently listed with a head tube angle of 64.5 with a 150mm fork, if you put a 170 on there it will be even slacker/longer.... I would guess under 63*. Also for me (tall AF), the slacker seat tube angle creates issues climbing.

[casual_build]

the 1002 is currently listed with a head tube angle of 64.5 with a 150mm fork, if you put a 170 on there it will be even slacker/longer.... I would guess under 63*. Also for me (tall AF), the slacker seat tube angle creates issues climbing.

If you look at the geometry, the 64.5 degree angle is for a 572mm axle to crown fork. I am not sure what fork they were using that has 150mm of travel and is 572mm axle to crown. Most 160mm forks are 571mm so actually under length. Using a measuring app my head angle looks to be ~64.1 with a 170mm fork

[casual_build]

Check out what this guy thinks about taking a 160mm frame and putting a 170mm fork on it.

https://youtu.be/aZ40ikmWLXM?t=583

[endo.alley]

I have only used a 170 Rock Shox Lyric. Works fine. I don't see how a smaller fork will improve by much. I don't think this bike will ever be a screaming climber no matter the fork length. But it's a solid ok climber.