frame geometry experts, please help with specs
I'm thinking about ordering a new frame modeled after a Thorn eXp, Rohloff specific, sus fork compatible, mtb-ish expedition tourer. I want a custom fit so not looking for an off the shelf Thorn. The BB will be a slightly higher than the LHT to allow for tad more clearance over rough terrain (+5 mm).
The 2 specs I'm having a hard time deciding on is the 1. Chainstay Length, and 2. Head Tube Angle. Please critique my thoughts:
1. I like a a smooth ride and stable handling with a heavy load, so I was thinking 46cm stays like the LHT. But any longer and I'm concerned about too much rear wheel skid when climbing on loose dirt. I'm aware tho that I'd have the weight in rear panniers to hold the wheel down to improve traction. Or perhaps 47.5 stays like on the Sakkit 26?
2. I will use both a sus fork and a rigid fork, depending on the occasion. As for Head angle, I like stable steering, but not too stable because when riding on bumpy dirt with front panniers, I don't want the steering to feel too sluggish.
I discovered that when I put front panniers on my folding Bike Friday, that the steering actually improved! It felt like the weight actually stabilized the twitchy nature of 20" wheel steering. This makes me think that If I spec'd a slightly steeper head angle (like 72 deg), the extra responsiveness would counter the effects of the mass in the front panniers.
These 2 specs seem independent from the frame size, but I'll give that if it matters, 54cm Also I picked up a used Gunnar Rock Tour for testing purposes, and will use it as a baseline to help decide. But I also want opinions as well.
so what chainstay and head angle would you choose? thanks in advance