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Fork question for Specialized expedition sport



 
 
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  #1  
Old June 25th 03, 08:16 PM
Alan McClure
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Default Fork question for Specialized expedition sport

Alright, I ride a specialized expedition sport. I've owned this bike
for almost 2 years now. I really like it because it never causes me
any trouble, and is light enough (29 pounds) to be just fine for
recreational use. Anyway, I won't have nearly enough money to
purchase a new bike for maybe 3-4 years, but since I ride every
day(that is possible at least without missouri mud), I would like to
replace one more thing on my bike. It already has had some standard
things replaced, like the steel handlebar, and the seat post which
weighed about as much as a gorilla. So, due to the time I spend on my
bike, I would also like a better and lighter fork. Anyway, apparently
(so I'm told) my front fork has about a 68 mm travel or so. The guy
at the local bike shop suggested that if I want to replace the fork,
that I find a good deal on an 68-80mm at the uppermost range travel
fork. He said anything greater than that would mess up the geometry.
It seemed to make sense the way he explained it. He said he thought
that Manitou made a 80 mm Black, and that Rockshock had a Psylo in the
80mm range as well. He also mentioned Marzocchi. Anyway, my question
is, when I look around at the specs for these forks, they are usually
80-100mm or 100-120mm. I'm not having any luck finding anything even
on the manufacturer's websites. So, is it even possible to find
anything--am I looking in the wrong places? Also, how badly would the
geometry be "messed up" with an 80-100mm fork, and in what way? I
really don't know much about the geometry of my bike let alone bikes
in general, so I can only learn, but since the LBS said that a
80-100mm fork would bring the front of my bike up too high probably I
wanted to see what you guys/gals say.

Anyway, any help is appreciated. And thanks to all who helped me with
my Hayes brake issue--it is now perfect, and I love it.

Thanks,
Alan
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  #2  
Old June 25th 03, 08:58 PM
David
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Default Fork question for Specialized expedition sport


"Alan McClure" wrote in message om...
Also, how badly would the
geometry be "messed up" with an 80-100mm fork, and in what way? I
really don't know much about the geometry of my bike let alone bikes
in general, so I can only learn, but since the LBS said that a
80-100mm fork would bring the front of my bike up too high probably I
wanted to see what you guys/gals say.


It might bother you. Measure your head angle, and the axle to crown distance.
Measure the axle to crown distance of the fork you are thinking about buying.
If you can calculate the new angle, great. If not, you can elevate the front wheel
enough to account for the longer fork, and measure the head angle again.

If you don't have the angle checker, your LBS probably does. If you don't measure
this stuff, and simply take other people's word for it, you may not be pleased with the
results.

Most people seem to like 71 degrees for their XC bike's head angle. You can go as
slack as 68.5 degrees and have it work pretty well in most circumstances, but you might
find giving up 1 degree to be annoying.

David.


  #3  
Old June 26th 03, 02:54 AM
Alan McClure
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Default Fork question for Specialized expedition sport


"David" wrote in message
...

"Alan McClure" wrote in message

om...
Also, how badly would the
geometry be "messed up" with an 80-100mm fork, and in what way? I
really don't know much about the geometry of my bike let alone bikes
in general, so I can only learn, but since the LBS said that a
80-100mm fork would bring the front of my bike up too high probably I
wanted to see what you guys/gals say.



Most people seem to like 71 degrees for their XC bike's head angle. You

can go as
slack as 68.5 degrees and have it work pretty well in most circumstances,

but you might
find giving up 1 degree to be annoying.

David.



Well theoretically, if an 80 mm travel fork like this:
http://makeashorterlink.com/?J2BC12E05
changed the geometry by a few degrees, couldn't I counter that change with a
with a stem that has less of an upward angle. Or am I missing something
else too? Anyway, I realized that my current travel is 63mm, not 68mm. So,
to go to 80mm would be adding approximately 3/4 of an inch rise to the front
end. Anyway, I should do as you suggest and have things measured, but I'm
wondering about the stem idea.

Alan


  #4  
Old June 26th 03, 09:07 AM
spademan o---[\) *
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Default Fork question for Specialized expedition sport


Well theoretically, if an 80 mm travel fork like this:
http://makeashorterlink.com/?J2BC12E05
changed the geometry by a few degrees, couldn't I counter that change with

a
with a stem that has less of an upward angle. Or am I missing something
else too? Anyway, I realized that my current travel is 63mm, not 68mm.

So,
to go to 80mm would be adding approximately 3/4 of an inch rise to the

front
end. Anyway, I should do as you suggest and have things measured, but I'm
wondering about the stem idea.

Alan


The problem with adding a longer travel fork is not only the higher
handlebar position, which you correctly pointed out would be sorted by a
lower rise stem or maybe you could just lose a few spacers if there are any,
but also, and this is turning out to be the longest sentence in the history
of AMB, the longer fork will in theory decrease the head angle of the bike.
The head angle is a major factor in how easily the bike steers, steeper head
angle = faster steering, slacker = slower. Too steep and the bike will feel
twitchy - some folks like this, mainly xc riders, OTOH too slack and the
bike will be slow to steer but very stable at high speeds which is (one
reason) why DH bikes have slacker angles. Its a balance thing. I said in
theory because you may find that at rest a new fork is longer, but actually
has more sag than your old fork and so when you are sat on the bike the
angles all return to normal. In essence I am saying I have no clue whether a
new fork will screw up your bike or not. HTH!

Steve E.


  #5  
Old June 26th 03, 12:25 PM
ctg
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Default Fork question for Specialized expedition sport


"Alan McClure" wrote in message
om...


snip

There are many forks available that are only 80mm or can be set at 80mm. I'd
go somewhere else if your shop can't think of any that come in that range.
Personally I'd go with Manitou or Marzocchi if cost is an issue. New
Zocchi's are expensive but it's not hard to find deals on older ones.
Manitou has several inexpensive forks and you can also find deals on older
models.

Chris


 




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