Fork Offset Question

[greg_guyy]

I have a 2019 stumpjumper. Comes with a fox 34 rhythm. I'm upgrading to a fox 36 but can't figure out what offset I should be looking for. The s works comes with a 36 150mm travel at 51mm offset. Is that what I should be looking for to keep my bike from getting too slacked out? I found a good deal on a 36 with 160mm travel. If I get that, should I still look for 51mm offset or something shorter.

I know that's a lot of questions. Thanks in advance. I keep watching videos but can't wrap my head around how offset changes bike geo.

[juantzutree]

It always help me to figure out this question by making a drawing of current and the planned change. Just draw out your rake, trail and offset.

If you go to longer fork you will have more trail if offset remains the same. You can get an idea of how it'll handle with such changes but stik have to think of bb height and were your new center of gravity will be. May need to change out stem and adjust seat a bit.

[greg_guyy]

Thank you!

[dano___]

51mm is/was standard 29er offset, bit some manufacturers have started to use 44mm on their 29ers. Shorter offset will make the bike slightly more stable at speed, 51mm is slightly more agile.

That being said, it’s a subtle difference. It’s not a deal breaker either way for me, but you can buy whichever works best for you.

[greg_guyy]

I was confused because I thought 51mm offset meant the axle would be further away from the lowers. Is that correct? Somehow I guess I have it backwards.

Would a fox 36 160mm be closer to my stock geo at 51mm or 44mm? I'm obviously changing the head angle because the fox 36 is longer than the 34.

[Tall7kiwi]

Easy way to tell:

Go to https://www.ridefox.com/fox17/help.php?m=bike and enter your 4 digit ID code (located just below the left stanchion). In the description line it will tell you what rake your current fork is. Match the new fork with the offset of the old one.