My question is directed to Dan, because of his ability to give us frame geometry info that is understandable,but if any others have ideas please join in.
Background. I ride a M size Giant Trinity.This is my first non road geometry bike,and after 6 months of riding it can say I love it.Very fast ,comfortable,and in most conditions;stable.My seat is as far forward as it will go so S.A. is between 76 to78 deg.Using the first
large spacer under a 100 mm. stem, low pos.Bar is Easton base with VisionTech S bends,rests with low spacers.
In this position I am low,comfortable, and after 4 hrs can get into a good run.
Looking thru Dans ideal geometry, I see the most obvious difference is the wheelbase no.Slowtwitch ideal for a 54/56 frame is 99.8 t0 102.4.My bike is 95.2.Some of the difference is in the Giants short chainstay,but I am wondering if the rake and trail and 73 deg. H.A.also are a factor.Specifically,is there an after market fork that would give me a longer wheelbase,and perhaps even give more downhill high speed stability.
The bike is not scary at speed ,but hills steeper than 8 deg.can get a
bit shakey.
Sorry to be so long ,but I joined this forum in part because of all the info on fit and geometry.If there are no forks that would give me more stability and a longer wheelbase I will eventully look at a different frame. Thanks in advance.
I don’t know that any fork is available that would stretch your wheelbase more than a few millimeters. Plus, even if such a fork were available, it would drastically reduce your trail (maybe even make it negative!) and make the bike extremely twitchy.
“Specifically,is there an after market fork that would give me a longer wheelbase,and perhaps even give more downhill high speed stability.”
don’t change the fork. you’ll reduce the trail and end up with a bike worse for the change. if the bike works for you now, just go with it. while i prefer giant’s new trinity alliance geometry, it sounds like you and your bike (and its geometry) have bonded. i wouldn’t worry.