I have a Giant Roam with a Suntour 63mm fork. I've recently started experimenting a little bit to see how forks with a different height (the axle-to-crown measurement) will feel. As noted above, a shorter fork will increase the head tube angle because the front of the bike will be lower to the ground and the head tube will become slightly more vertical. I don't really like the looks of so-called suspension corrected forks and "standard" forks are much more common (and less expensive). So I wanted to try to see what I could find out without actually buying anything...to see if I could approximate the height of a standard fork with my suspension fork.

To test how dramatic of a change this is on my Roam, I just removed the springs from the fork and rode around with the fork in full compression. The axle-to-crown measurement fell from about 475mm fully extended (which is how I typically ride it, locked at full extension) to about 425mm or so fully compressed. Yes, the fork is advertised as having a 63mm travel, but it's really about 50mm in practice. Anyway, I rode around with it at that height and it actually didn't feel dramatically different, aside from the much lower handlebar height. This is the geometry that changed:

• The head tube angle increased, from 70.5 degrees to about 73 degrees. With the same fork offset (that didn't change), the trail was reduced from 71mm to about 57mm. This makes the steering feel a little lighter (easier to turn). There are pros and cons to this, documented comprehensively on the internet. I liked the change (I prefer less trail to more trail).
• The seat tube angle is increased, from 73 degrees to about 76 degrees. This requires a seat angle adjustment on top of the seat post, but was otherwise relatively unnoticed by me. I am moved a little further over the pedals which, in theory, provides a little more efficiency. Again, whatever theoretical advantages or disadvantages exist, I didn't feel much change by this.
• The bottom bracket height decreased, from 28.9mm (11.4") to 26.7mm (10.5"). This lowers the cranks and increases the chance of pedal strike.
• Because the head tube is about 50mm lower (about 2 inches), the handlebar is also about 2 inches lower. I already have a riser bar on this bike and prefer the grips to be a few inches higher than my saddle. This change put them at or just slightly lower than my saddle. If I kept this configuration (a shorter fork), then I would need a stem riser to compensate.

So...what is the take-away? Well, that turned my Roam's "hybrid" geometry closer to that of a traditional "road bike". There are obviously other frame differences, but Giant's Contend (a basic all-rounder road bike) has similar head tube angles (in the 72-73 degree range), similar seat tube angles (in the 73-75 degree range), similar bottom bracket heights (about 10"), and similar trail numbers (in the 55-66mm range). I rather liked how the bike handled and felt, aside from the really heavy rigid fork (!), and I think I'd like it a lot if I had a stem extender on it. I wasn't particularly comfortable with it without a stem extender, so I have the springs back in the fork and I'm riding it at full extension again.

One of my challenges is finding a style of rigid fork that'll look nice with the Roam. It has an aluminum frame with relatively large frame tubes. A chromo steel fork with thin tubes probably won't look quite right. Forks with larger blades are generally aluminum (poor ride quality) or carbon (fairly expensive), so I haven't really pursued it much beyond initial curiosity.

The point of my post is that you CAN experiment a little bit if you're really curious about what a standard fork would do to your bike. You may end up liking the result.