fork lengths

[bfloyd6969]

I currently have a suspension fork with a 413mm axle to crown length. I have a rigid fork I want to put on that has a 397mm axle to crown length with about a 40mm rake. How much will this affect the angle of the steer tube? Can I use spacers to bring the bars back up to the same height and not "feel" the effect of the shorter fork? I should add that this is for a 26in. wheel. Thanks.

[rockyrider]

Is the 413mm A-C height without sag? That must be a 63mm fork as that's fairly short. The sagged height of that fork should be around 398-400mm so it should be a wash.

[bfloyd6969]

Is the 413mm A-C height without sag? That must be a 63mm fork as that's fairly short. The sagged height of that fork should be around 398-400mm so it should be a wash.

Ok, my bad, I got the measurements wrong. It is a RST Omni 191 (reaon for wanting to change) with 89mm of travel. As I'm not exactly sure where axle to crown is measured; it is 425mm from axle center to top of fork leg and 450mm from axle center to bottom of head tube (no sag). Which is the correct location to measure? What length rigid fork do I want to match? Thanks.

[rockyrider]

This is the axle to crown height. A rigid fork A2C around 430mm would maintain the current geometry as you'd expect 15-20mm of sag. A 397mm A2C fork would have about 1.5 degree steeper headangle which would be kinda twitchy.

The spacers would restore the bar height but wouldn't do anything about the steering geometry

[bfloyd6969]

This is the axle to crown height. A rigid fork A2C around 430mm would maintain the current geometry as you'd expect 15-20mm of sag. A 397mm A2C fork would have about 1.5 degree steeper headangle which would be kinda twitchy.

The spacers would restore the bar height but wouldn't do anything about the steering geometry

Thanks for the help. The 397mm a - c is out. So far, all the suspension correct rigid forks I have been seeing are either 410mm ~ 413mm a - c (most of them fall in this range) and then a couple of them around 450mm a - c.

Unfortunately my budget restricts me to a certain couple. They are a Nashbar rigid with a 453 a - c ($49), and a Surly 1x1 with a 413mm a - c ($55). I rode my current set-up today and paid attention to the sag; because I have the fork on its highest setting (due to the poor quality of the suspension), it was mostly not compressed and only compressed when I was out of the saddle. So, would it be best for me to go with the 453mm a - c and lower my stem a bit to keep the same steering feel? Thanks again.

[rockyrider]

The Nashbar sounds like the best bang for the buck, you likely wouldn't even feel the 3mm height difference.

[bfloyd6969]

The Nashbar sounds like the best bang for the buck, you likely wouldn't even feel the 3mm height difference.

Thanks for the help and advice.

[bfloyd6969]

Ok, this has got me thinking; maybe I should consider going with a the shorter 410mm a - c rigid fork and put a 29in. wheel in there, running a 69er. Would that sit too high? Maybe use the 397mm?

[rockyrider]

Ok, this has got me thinking; maybe I should consider going with a the shorter 410mm a - c rigid fork and put a 29in. wheel in there, running a 69er. Would that sit too high? Maybe use the 397mm?If you're going to throw 29" wheels into the mix, you need a disc fork/wheel as the canti studs won't line up. Maybe a Surly Karate Monkey fork would be in order.

[bfloyd6969]

If you're going to throw 29" wheels into the mix, you need a disc fork/wheel as the canti studs won't line up. Maybe a Surly Karate Monkey fork would be in order.

Thanks. Wouldn't the Karate Monkey sit too high with the addition of the 29in. wheel? What about a cyclocross fork (like the Surly Cross)? I could still use v-brakes and the a - c lengths are about 400mm. I would just have to run a narrow tire, which I do now anyways (1.5 Conti Cross Country).