Using a Touring fork on a CX bike.
 

I'm considering installing a Salsa Vaya touring fork on My Soma Double Cross DC bike.

http://salsacycles.com/bikes/vaya/

http://www.interlocracing.com/forks.html

This would allow me to use disc brakes and I would also get low rider mounts for touring.

The Salsa fork is dimensionally not the same as the Soma (made-by-IRD, Straight Blade Disc Cross Fork). The crown-to-axle length is 405mm on the Salsa while the crown-to-axle length is 395mm on the Soma fork. The offset on the Salsa fork is 45mm, the offset on the Soma fork is 44mm. The headtube angle on the frames is the same at 72 degrees.

Does 10mm of crown-to-axle length really matter?

I doubt it would matter.
even then, you wouldn't know until you hit the road and develop a speed wobble.

LOL, that would be a problem!

Very very unlikely that 10mm of axle-crown length would cause any problems. Extra unlikely that raising front end and slightly slackening head angle would make speed wobble mor elikely... it will probably make the bike slightly more stable, but the 1mm of extra rake would offset this slightly.

Should be fine.

BL

The 10 mm of fork crown height would tend to slacken the head-tube angle an eentzy amount. That coupled with the 1 mm less fork offset would cause more trail and tend to make the bike more stable at speed rather than less. But it's such a tiny amount I doubt that you could tell the difference. I changed from a 45 mm offset fork to a 40 mm offset fork (5 mm change in trail), and the difference was barely perceptible.

I think you may well feel the change in head angle this will cause.

But only until you're used to it... the second time you take it out it'll prolly feel normal.

A bit of trigonometry tells me this will take about 0.6° off your head angle.

Switching to Salsa fork will increase rake by 1mm, therefore decreasing trail slightly. Longer fork will decrease head angle therefore increase trail slightly. One will partialy cancel the other out. In fact, if we use Kimmo's 0.6 deg. change estimate, the new head angle will increase trail by approx. 1.1mm (depending on wheel and tire size), and the rake will decrease it by ~ 0.9, so there should be a net gain of approximately 0.2mm. It is very very unlikely that you will notice a 0.2mm change in trail, and it definitely won't cause any problems.

Thank you LD-74 and Kimmo for the detailed explanation.

Happy Thanksgiving to all!

Similar question, I got a custom steel Kusaka cyclocross frame off ebay for a steal, but it came with no fork so I bought a surly long haul trucker fork to go with it.. I just figured it would make the bike feel a bit less "racey" than if I got a cyclocross fork? Or will this mix and match give my bike handling that feels "stupid?"

Hard to know for sure because we don't know what fork was originally intended for your bike. Quite likely, though, that as in the OP's case, the stock fork and a standard aftermarket touring or CX fork are pretty close and it won't be a problem.
Two things to keep in mind: your frame might be stupid handling anyway - perhaps a customer insisted on some geometry that didn't work out as well as he hoped or there is something else funny about the frame - like it is designed around 650A wheels or something.

I am not Familiar with Kusaka but if it doesn't work out with the Surly fork maybe you can contact the builder - he likely has the dimensions of the fork to which he designs his CX frames.

now that I think of it, the seller told me it was a Kusaka Prototype.. i just figured it was a prototype because it has upside down cantilever mounts on the rear (for mud shedding was the explanation)... but maybe the geometry was prototype in a very bad way, lol. :eek: :twitchy: :cry:

Why not get the steel Soma DC fork? It is made for your bike and has mid-fork eyelets for a low-rider rack.

oh damn... why didn't i think of that... the soma DC fork is a way better idea.. DOH!!