eric aldinger
This is a piece of the bike it is worth reading up on. It is a part I have
upgraded on most bikes and felt the difference (tires are the only thing
that makes more difference). I am not the best at this but others will
chime in and point out the gaps.
Some riders prefer a rigid fork. These tend to save weight and money. They
do not divert any pedaling force into fork compression. The downside is
that they force the rider's body (through skill and strength) to absorb the
impact of repeated trail obstacles.This can cause rider fatigue.
Telescopic forks are used to mitigate some of the fatigue by absorbing
impact for the rider. These forks have sliders (outer part), stanchions
(inner part), a crown, and an axle interface. The stanchions are usually on
the top, but can also be inverted to the bottom (Maverick DUC/SC and the
Manitou Dorado). Inverted forks are smoother when starting compression, but
there is minimal difference.
Crowns and sliders can be made of aluminum or carbon. The differences are
the same as in road racing, except that most mountain bike forks use metal
as the primary material.
The interface for the axle can have 9mm tabs like a road bike, or can be
one of several competing standards of thru axle. Most of mountain bike
history (especially in XC) was predicated on 9mm tabs. Thru axles are
becoming much more common, but require some special awareness. One thing is
thru axles require roof rack adapters. Another is that your front hub needs
to match your axle. Some hubs allow you to switch between different axle
configurations by changing the axle caps (which cost 20-40 bucks). Other
hubs have a dedicated interface that will only work with one type of fork.
The value of the thru axle is addition stiffness, which increases the
precision of your steering. The downside is having to remember your rack
adapter when you car pool with different people and not being able to
borrow your buddy's wheel from the pit.
The stanchions house the oil, dampening valves, and springs for the fork.
Most forks allow you some control over rebound, how quickly the fork pops
back after compression. This is usually a set and forget control. You do
not want it coming back to fast as you will not get full use of your
travel, and feel like a yoyo. Too slow will cause it to feel like it is
mushy and also not have full travel on rapid compression (three rocks in a
row). Some forks have the ability to set the amount of force required prior
to compression. This compression dampening allows you to say, ignore small
bumps, but compress on larger rocks. Compression of the fork can cause you
to lose momentum, or suck up energy from your pedaling. Lack of compression
from the fork forces you to use your body to absorb the energy of the
obstacle. This can cause additional fatigue in the rider. So there is a
balance. Dampening extends into the form of a lockout, which prevents the
fork from moving at all. This is helpful on non-technical climbs, or
sprints. You can have a fork with both types of controls. Compression
dampening can also be controlled through an inertial valve that acts like a
lockout for the first small bump, and then then allows the fork to move
freely on subsequent objects in close proximity.
The primary spring mechanism can be coil, air, or a combination of both.
Coils tend to deliver a more consistent/linear feeling (buttery smooth,
predictable) as the spring compresses. Air is noticeably progressive as it
starts out feeling soft/smooth and ramps up the resistance to prevent
bottoming out. Metal springs come with a weight penalty. and expensive air
forks are fairly smooth and predictable. Most of the higher end XC forks
use air springs. When setting up either type of fork, you need to tune the
sag (distance the slider travels along the stanchion when the bike is
weighted by the rider). This tends to be initially easier on an air fork.
You just pump the fork up to body weight of the rider, and remove air from
the spring with the rider in their normal gear (helmet, shoes, water,
tools) on the bike in race position until you get 30% sag (or whatever your
manual or preference states). The down side is that this setting needs to
be adjusted from time to time (due to leaking or rider weight changes).
Coils springs have settings to allow you to adjust the load on the spring.
This can be almost as simple as adjusting the air fork, as it is just
spinning a ring or dial.Or you may have to swap out springs if you are a
heavy or light rider. That part can be a small pain, and air forks do not
have this issue. Always follow the manual on how to tune the fork
initially. You do not want to use all 4" of your travel when you hit a 2"
rock. You do not want to see your fork only traveling 2" when you hit a
series of 4" - 6" rocks.
Last note. Any travel you do not need is wasted momentum and extra weight.
80-100mm forks with 32mm stanchions for general XC riding and racing,
120-160mm with 36mm stanchions for rough trails or general free riding.
People ride all sorts of forks for all sorts of terrain. A good fork is a
perfect marriage of technology compensating for any inability in the rider
to absorb/avoid the momentum deflecting obstacles in the trail. If you want
a fork recommendation go for the Fox 32 Float 100 FIT
Terralogic.
It is ridiculously cool and expensive.
On Fri, Mar 30, 2012 at 12:17 AM, Stewart Campbell wrote:
> Well y'all have been so helpfull with my questions so far...way more
> informative than reading blogs from other newbies that don't even race and
> think they know it all. ha ha
>
> Anyhow...front suspension forks. Once again, I'm on a 26" hardtail, I
> weigh 130lb, and I ride XC.
>
> What is the prefered amount of travel and what does the amount of travel
> really mean for feel. And what are the different types of suspension...ie:
> coil, air, etc.
>
> Also keep in mind I'm on a budget, at least untill the pressure washing
> season really strats up.
>
> Thanks,
> Stewart Campbell
> www.bridgecitypw.com
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--
Eric Aldinger