Head tube angle/increased fork travel

Alright, my bike currently has a 70mm head tube angle with 63 mm travel on
the fork. I mentioned in another thread that I was thinking about getting a
new fork like this one:

http://makeashorterlink.com/?J2BC12E05

or another 80mm travel fork (any suggestions for a nice price--marzocchi
maybe). Anyway, someone mentioned that most people find 71 degrees to be
about right for the head tube angle. Of course, mine is already off that
mark by 1 degree. Does anyone know how much the above fork would throw off
the angle even more? Is there any way at all to counteract that effect
without having a frame builder replace the head tube. If not, then does
anyone have any other suggestions?

Thanks again,

Alan McClure

"Alan McClure" wrote:

Alright, my bike currently has a 70mm head tube angle with 63 mm travel on
the fork. I mentioned in another thread that I was thinking about getting a
new fork like this one:

http://makeashorterlink.com/?J2BC12E05

or another 80mm travel fork (any suggestions for a nice price--marzocchi
maybe). Anyway, someone mentioned that most people find 71 degrees to be
about right for the head tube angle. Of course, mine is already off that
mark by 1 degree. Does anyone know how much the above fork would throw off
the angle even more? Is there any way at all to counteract that effect
without having a frame builder replace the head tube. If not, then does
anyone have any other suggestions?

The change from a 63 to 80mm shock (assuming the ride height will
change by ~15mm once sag is factored in) will be between close to
another degree (probably about 0.7-8 degrees, depending on a lot of
minor things like wheelbase).

That would put your head tube's effective angle at 69 degrees - pretty
slack, but not horribly so. I doubt you'll find the difference all
that drastic though. If it's a stiffer, better fork the result will
be worth it.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

"Alan McClure" wrote:

"Mark Hickey" wrote

The change from a 63 to 80mm shock (assuming the ride height will
change by ~15mm once sag is factored in) will be between close to
another degree (probably about 0.7-8 degrees, depending on a lot of
minor things like wheelbase).

That would put your head tube's effective angle at 69 degrees - pretty
slack, but not horribly so. I doubt you'll find the difference all
that drastic though. If it's a stiffer, better fork the result will
be worth it.

I think maybe I accidentally sent you an e-mail rather than replying to the
group. So, here is what I wrote:

Do you think there is any other reasonable option--including replacing the
headtube at a frame machine shop? Would that cost an unreasonable amount of
money? I am assuming that it would, but I don't really know. It seems like
there would have to be some way around the loss of another degree, but maybe
not.

You did send me an email... here is/was my reply...

Probably not worth it unless you have an emotional attachment to that
frame that makes it worth spending much more than it's worth to
upgrade it. I'd recommend trying the shock and see if you like the
results. If that doesn't work out, there are plenty of frames out
there that you could buy with appropriate angles (and that are
probably lighter and stronger to boot).

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

Alan McClure said...

Alright, my bike currently has a 70mm head tube angle with 63 mm travel on
the fork. I mentioned in another thread that I was thinking about getting a
new fork like this one:

http://makeashorterlink.com/?J2BC12E05

or another 80mm travel fork (any suggestions for a nice price--marzocchi
maybe). Anyway, someone mentioned that most people find 71 degrees to be
about right for the head tube angle. Of course, mine is already off that
mark by 1 degree. Does anyone know how much the above fork would throw off
the angle even more? Is there any way at all to counteract that effect
without having a frame builder replace the head tube. If not, then does
anyone have any other suggestions?

Thanks again,

Alan McClure

I just went from 80mm travel to 125mm travel when I installed my Fox
Vanilla fork and I love the geometry change. One reason I bought the Fox
was that it converts between 80, 100, and 125mm travel. I figured that I
would have to knock it down to 80 to get good handling, but now I see no
reason to bother with it. When I was having problems with my stock 80mm
fork, I talked with the guy who designed the bike and he said that they
run them at 105mm all the time and they feel great. This conversation
came up when I arranged to trade up my defective 80mm fork for a Duke SL
U-Turn which has a travel range of 63-105mm. My experience agrees with
his. I do have the sag set to the maximum recommended, and I may find
out that there may be times when less travel would be better, like on
challenging uphills, but there are advantages and disadvantages to
everything. It's all a matter of taste, and the differences can be
subtle. I don't think you should lose any sleep over the difference
between a 63 and 80mm fork.