Fork Trail/Rake comparison

[NYCfixie]

I know this is not an easy topic to discuss and/or explain. I do "mostly" understand how rake, head tube angle, and even tire size can affect trail.

As I am looking to have a custom Ti frame built - a club ride frame rather than a race or touring frame. More than one person has suggested a 71.5 HTA with a 50 rake fork for a 6.10 trail. My TT will probably be a 53cm and I know the dread of all small frames is toe overlap but with 10.5 shoes I have always had to deal with toe overlap so I do not worry about it. I am hesitant to agree to a 71.5 HTA because I worry that good quality 50mm rake forks may not be around forever. There is Enve, WoundUp, and Seven (assuming they will sell one for a bike not made by them) but what about 10 years from now?

Assuming for a moment that I want 6.0 of trail, and everything else on 2 hypothetical frames are identical (STA, BB drop, chainstay length, tire size, etc.) what would be the difference between the two bikes if each had one of the following HTA and Rake options:

71.5 HTA and 5.1 rake fork for 6.0 trail
72.5 HTA and 4.5 rake fork for 6.0 trail

Why choose one setup over another?

Thanks in advance for the help!

[blasdelf]

The differences you get in arriving at the same trail figure with a different angle/offset are super marginal — would be overwhelmed by a slightly different tire choice or even rim weight

But if you keep the TT length the same, the front-center will change, and that'll make a huge difference.

My advice is to ignore the TT and focus solely on the front-center.

You've got enough existing bikes piled up that you should measure it on them along with the trail and see what you like about how each handles, this shit is easier to experience than to talk about. If your saddle position vs. the BB varies much on them that could easily confound the test, moreso than the bb drop or cs length. Forget about differences in the handlebar location, what really matters is your hip angle / where your body mass is, and that's dictated by your ass position when you're developing power.