Road bike geometry: handling with large offset fork + slack headtube?

[marciero]

Also regarding Poertner's remarks-he also notes that seat post contributes more to flex than frame in the lab, and conjectures, even in light of all the studies he cites about riders not detecting differences, that that may be why aero frames are regarded by riders as stiff. Again, very small amounts of flex here-much less than we see with the fork in the video. Again, in what ways are the bikes riders cant distinguish in fact different? These tests demonstrate that whatever the differences are, they are not large enough that riders can detect them. I'd be very surprised if most riders could not blind ID, say, a 1990's Cannondale CAAD and a Colnago Master X light or even a garden variety skinny tube thinwall steel with the same wheels, tires, and pressure- even with identical geometry. I am certainly open to evidence, and these studies may suggest that the contribution of frame flex is less than the perception.

[andrewsuzuki]

Summary

Thanks to those pointing me in the right direction (esp. regarding front center). Currently I'm thinking that this is possible without sacrificing agility or having too much wheel flop.

Since the original post I've found four examples of recent bikes that manufacturers have specced with high offset and slack headtubes:

• Rodriguez Phinney Ridge, see this article: https://www.rodbikes.com/articles/ph...vel-bikes.html They designed a fork for this model with a 55mm offset and they're suggesting using it on HT angles down to 70.5 deg for a gravel bike.
• Seven Matador Fork, a new carbon fork for gravel bikes, also with a 55mm offset. No mention of HT angle in this article however. http://www.handbuiltbicyclenews.com/...ke-gravel-fork
• Smaller sizes of production gravel bikes such as the Velo Orange Pass Hunter (thanks Ernesto!)
• Cannondale OutFront geometry as found on the Scalpel. https://www.cannondale.com/en/Intern...-geometry.aspx Yes it's not a road bike, and it's just marketing speak, but: "By using a longer fork rake to reduce the trail, we can exploit the stability of a slack head angle, without the sluggish slow speed handling usually associated with it. It's the best of both worlds: slack and stable on fast, challenging terrain, yet quick and agile at slow speeds and on climbs."

My thought on front center at the moment is that yes it'll increase by a nontrivial amount (+19mm) compared to my CAAD10, but I'm also used to riding XC mtbs with significantly more front center (+110mm), so how bad can 19mm be? Idk, we'll see.

[Mark McM]

Originally Posted by andrewsuzuki

My thought on front center at the moment is that yes it'll increase by a nontrivial amount (+19mm) compared to my CAAD10, but I'm also used to riding XC mtbs with significantly more front center (+110mm), so how bad can 19mm be? Idk, we'll see.

I don't think the front center will be concern, but as far as the flop: MTBs and bikes intended for upright riding positions often have slack head angles, and therefore more flop. But these bikes also tend to have wide handlebars and short stems, which makes countering flop easier. Flop has a bigger effect on bikes with narrow handlebars and long stems.

[Spoker]

I wonder if the comfort you're seeking does not come from a light tubed frame, more than the actual fork. I remember riding a race over a cobbled section with a light Ti frame that handled the hits so well (as would do an Alan / Vitus).