Tandem Cycling - Carbon fiber forks for tandems.

One other item to consider is finding a headset with a different stack height. Cane Creek makes one with +5 on the lower cup. This would help with the crown height issue.

http://www.canecreek.com/component-headsets?browse=type&type=traditional&cat=1-1-8-threadless&product=s-3-plus-5


The Alpha Q is 374 crown height per TG's numbers supra, the edge is 367mm. +5 would move the fork REAL close to where the Alpha Q is considering King quotes 12.9mm. This would give us an effective crown height of 371mm.

I'm reasonably sure we can find a down hill headset that might can get us closer; +7 or +10, more I'd be worried about too much extra stress on the head tube. Although I've not been able to find a higher lower stack HS. Even at 371mm with the Cane Creek, I'm still around 25-30mm lower on my Trek. The *only* solution for me would be to replace the head tube. However, I find the handling acceptable, but on the twitchy side of acceptable, as it is on the Trek with the Edge 2.0 fork.

Anyone else have any thoughts?

have you tried a ck? overall is slightly over 31, and the lower stack is 13.7. i presume you're looking for something taller on the bottom stack, yes?

http://chrisking.com/specs/headsets_all

with 25-30mm of overall difference as you mentioned (i.e., you're lower at the bottom), that seems like a lot, as in 1.5-2 degrees (+/-) of effective hta change. but maybe my math is wrong on that calc.

it's a maddening process, i feel your pain....

i've had to go through it once before on another bike, when the alpha q fork originally accounted for in the pre-build specs (i think it was a cs25) suddenly became unavailable (they went bust a day or two before the frame build began, so things had to get revisited).

have you tried a ck? overall is slightly over 31, and the lower stack is 13.7. i presume you're looking for something taller on the bottom stack, yes?

http://chrisking.com/specs/headsets_all

with 25-30mm of overall difference as you mentioned (i.e., you're lower at the bottom), that seems like a lot, as in 1.5-2 degrees (+/-) of effective hta change. but maybe my math is wrong on that calc.

it's a maddening process, i feel your pain....

i've had to go through it once before on another bike, when the alpha q fork originally accounted for in the pre-build specs (i think it was a cs25) suddenly became unavailable (they went bust a day or two before the frame build began, so things had to get revisited).

Your math is about correct. It's roughly 15mm per degree. However, the 'stock' Trek geometry was so jacked up I felt like the bike would never turn. I prefer the way the bike handles/rides now compared to the 'stock' setup. We are quite comfortable at 25mph in a corner with the way it sits. With that being said, I'd like to be able to relax a 'bit' and not be on my game 100% of the time, so getting the lower stack a bit higher would be the ticket.

Rough measurements on the Cane Creek that came off the bike are 10mm lower stack. So the king at 13.7 is +3.7 more than the stock one.

I went with a King HS on the bike when I put the fork on. After a bit more research, king does make a +5 mm lower baseplate.
http://chrisking.com/parts/baseplates

With this, I'm roughly +8. +10 would make me happy based on my general 'hunch' on how the bike feels. I've done a bunch of trail/height adjustments on motorcycles, so my 'gut' is that 10mm would fix the issue. It's close already, but not quite where I'd like it to be; I'd like to buy myself a bit of forgiveness if I don't get the line right at corner entry.

Just a quick follow-up/update on this. I Rode the Trek tonight after reassembly. Edge 2.0 fork. I ended up with a +5mm king lower race and a Cane Creek +5mm headset. This gave me roughly a bit higher than the Alpha Q fork.

The bike handles better and is more stable than the Co-Motion Macchiato we test road. That being said, we are properly 'fit' on this bike and were not on the Co-Motion. However, I'm not sure I could tell the difference between the two...

Ideally, I'd like the bike to turn in a bit 'quicker' I'm going to ride it the way it is for a few days to make sure I don't just compensate my line to get what I need/want. The next step will be to remove the King lower spacer and put the CaneCreek one in, which will give me roughly a 372 crown height.

I'll report back when I make the change and spend some time riding.