It's hard to tell from the picture but I think your head tube angle will be fine. Since you have a trailing-link fork set up, you can get away with a pretty steep H.T.A. If you haven't seen this already, this is how to determine your trail. There's no magic number because wheelbase also plays into how the bike will handle but from what I've read most people shoot for +2" to +5" of trail. Hope this helps.Truckd the head is set at 70 degrees. This is my first bike build and I am just using pictures off the net as a reference. I have see some that are 60 degrees and they start to look like choppers to me. If I am making a mistake with this please speak up. I live in Oklahoma.
Rake is one of the factors to take into account when determining trail, rake is the forward offset in the fork itself, typically the more rake you have, the more you need to lean back the head tube to get the correct amount of trail. His fork has very little rake, (maybe even none) so he can get away with a steep head tube and still have plenty of trail.I was told that 4" is the optimal number to shoot for less rake shorter steering range,longer rake more sensitive(touchy) medium is what is desired and at a high of speed (30+) a limited or wierd steering range could result in a catostrophic mishap.
I was told to pass this info on to add to what you might have already aquired.
www.carbidedepot.com then find the catagory for Rake&Trail Calculator.
Something to do a little R & D on for a bike of that magitude and calabur, you have an Great Deal in talent,don't over look the small details.
By the way, about what do you believe the HP rating would be on that Monster engine?
Very true, too little trail is probably more dangerous though, you can enter an uncontrollable death wobble at speed. With too much trail it would just be harder to turn but very easy to ride with no hands.So it looks like on trail there is such a thing as too much and too little. As in many things in life, moderation is the key for the best handling. It would be interesting to build a variable angle head tube and try out different trail values at different speeds. If I ever do a production run of the same frame over and over I'll try to figure that out.
Awesome Tom. Thats just cool.I built a metal lathe with a file and a drill press so don't let the lack of tools stop you.