Stupid question about geometry

larkim

It just occured to me that one feature of front geometry that seems more or less universal is the fact that the stantions are set forward of the steerer column, and the axel is forward of that too.

Presumably moving either of those back or forwards would have an impact on steering response etc? (Or would it, hence the post title?)

Are all forks built to the same spec in this regard, or are there forks which are more / less pronounced in this aspect?

Uber_Pod

You could try reading up on caster, mechanical trail and various other related areas until your brain starts to bleed.

It's a bit like shopping trolley wheels. With the wheel axle set behind, they flap around a lot. You don't really want that on a bike.
Having the wheel axle set forward makes it much more stable.

cooldad

Pretty much this ^^^, but they are different, a decnt explanation here.

https://www.pinkbike.com/news/To-the-Po ... ffset.html

My 29er has G2 (Trek/Gary Fisher) and it seems to work as they say.

cooldad

ps not a stupid question at, a very interesting one.

larkim

Cheers CD & Uber_Pod. That's a really informative link too.

Presumably the fork offset options that are referred to in the linked article are only generally available on high end forks which could be used on frames with very different head tube angles, rather than at "my" end of the spectrum (Recon, Reba, XC etc) where variability in frames is presumably a little less pronounced?

cooldad

Most (RS and Fox) have a different offset for 26, 27.5 and 29er forks, increasing as the wheels get bigger, but yes, apart from the more expensive models, you pretty much take what's offered.

Mojo and TF Tuned can custom make different offsets, but I think that's more for pros than us normal people.

larkim

Just watching the Giro, very little forward trail on those road bikes. Is that a newish development, i'm sure road forks used to sweep forwards a little.

The Rookie

It's because instead of being curved the legs are straight but at an angle to the steerer, the dropout is in about the same place relative to the steerer.

larkim

Ah, just a slight of hand in the design to make them look "cooler" then I suppose. Thanks!

cooldad

Probably cheaper/easier to manufacture as well. And stiffer. Old curved ones were more comfy I think.