Subject: 10  Off-Road


Subject: 10.1  Suspension Stems
From: Brian Lee <brian_lee@cc.chiron.com>

by Brian Lee & Rick Brusuelas, 1994

ABSTRACT:  Discussion of the differences between suspension stems
and suspension forks, and a listing of the pros & cons of suspension
DESCRIPTION:  The suspension stem discussed here is the
Allsop-type, which employs a linkage parallelogram and a spring
mechanism to effect shock-absorption.  Two models on the market
using this mechanism are the Allsop Softride, and  a version
produced by J.P. Morgen, a machinist based in San Francisco.
There is also a version put out by J.D Components of Taiwan
(advertised in Mountain Bike Action), however judging from
illustrations, this unit does not employ the parallelogram design
shared by Allsop & Morgen.  Other Taiwanese models may also exist.
The Girvin-type stem, which uses a simpler hinge and bumper, will
not be directly addressed here, although some of the comments
may also apply.

The Allsop-type suspension stem (suspension stem) works on a
different principal than a telescopic shock fork.  Instead of
only the front wheel moving to absorb shock, a stem allows the
entire front end of the bike to move with obstacles while the
rider's position does not change.

All suspension requires some form of "inertial backstop" to
operate.  A theoretical suspension (stem or fork) loaded with
zero mass will not function regardless of the size of obstacle
encountered.  This is because there is nothing to force the
compression of the spring mechanism.  It is essentially locked

In a fork system, the weight of the bike & rider both provide the
inertial backstop.  In a stem system, the rider's weight on the
handlebars provides the backstop.  Because of this, the two
systems "ride" differently.

Since most of the weight comes from the pressure of the rider's
hands, the stem system encourages a more weight-forward style of
riding.  Or perhaps placing the stem on a frame with a shorter
top tube so the rider's weight is distributed more on the front
end.  (Shortening the front end has also been applied by frame
builders on frames intended for use with suspension forks.  Ex:

What does this mean to you and me?  It means the suspension stem
requires a certain amount of the rider's weight to be on it at
all times in order to remain completely active.  For the majority
of riding, it's just fine.  The only difference is in extremely
steep descents, where you are forced to keep the weight back in
order to keep from going over the bars.

In this situation, much less weight is on the bars to activate
the stem.  Further, if one were to encounter a largish rock on
such a descent, what does one do?  The instinctive thing is to
pull back a bit to unweight the front and help the front wheel
over.  This removes all the weight from the stem area, and you
are now riding a rigid bike again.

A fork system is also affected by weight shifts, but not quite to
the extent that a stem is affected, because of the weight of bike
& rider coming through the head tube to be distributed into the
fork.  Even if you were to remove your hands from the bars on a
gnarly descent and hang with butt brushing the rear wheel, you
are still applying weight to the bike through the pedals.

All this, of course, is theoretical and YMMV.  I, for one, am not
always able to react to obstacles coming at me and leave the
front end weighted.  When that happens, I'm very glad I have

Now enough theory stuff, here's a summary of the advantages &
disadvantages of suspension stems:


1)  Lighter than a suspension fork.  This depends on the existing
stem/fork combination.  If the current stem and rigid fork are
heavy, then a suspension fork may be a better choice.  For
example, I've chosen the following items for comparison, as they
represent the lightest and heaviest of commercially available
stems & forks (weights for all stems are for conventional types -

Litespeed Titanium          211g
Ritchey Force Directional   375g
Allsop Stem                 625g
Fat Chance Big One Inch     680g
Tange Big Fork             1176g
Manitou 3                  1360g
Lawwill Leader             1588g

So say you have a Litespeed stem and a Fat Chance fork.  The
combined weight would be 891 g.  Switching to an Allsop would
change the combined weight to 1305 g, while a Manitou 3 would
bring it to 1571 g.  The Allsop has a weight advantage of 266 g
(9.4 oz).

OTOH, if you have a Ritchey stem & Tange Big Fork, the original
weight would be 1551 g.  Allsop stem => 1801 g.  Manitou 3 => 1735
g.  In this case, keeping the boat anchor of a fork and switching
to the Allsop would be a weight penalty of 66 g (2.3 oz.).

Of course, YMMV depending on your original equipment.

2)  Does not affect frame geometry.  A suspension fork
retrofitted to a frame, *not* designed for suspension, raises the
front end - sometimes as much as 1".  This reduces the effective
head angle and slackens the steering, slowing it down.  This is
especially true for smaller sized frames which, with their
shorter wheel base, are affected to a greater degree by the
raising of the head tube.  A suspension stem provides suspension
while preserving the handling of the bike.

3)  Torsionally rigid fork.  Telescopic forks all have a certain
amount of flex to them,  and the sliders are able to move up &
down independently.  This aspect of front  suspension forks has
spawned a new line of suspension enhancing products:  stiffer
fork braces, and bigger, heavier suspension hubs.  All to stiffen
up the fork.  This is  one reason suspension stems are favored by
some riders who ride lots of tight, twisting single track.

4)  No stiction.  Stiction, or static friction, is friction that
exists as the fork sliders rub  against the stanchion tubes.
This friction is an extra force that must be overcome  for a fork
system to activate.  Not a problem on large hits.  But more of a
problem  on small- and medium-size impacts.  Because the stem has
none, the stem responds  better to small, high-frequency bumps
(washboard) than many air-oil forks.

5)  More boing for the buck.  The Allsop stem provides up to 3"
of stiction-free travel,  at a cost of about $250, depending
where you go.  The majority of forks in this  price range only
offer 1" - 2" of travel, and are often heavy, flexy, and fraught
with  stiction.  The fork could be stiffened, but at the
additional cost of a stiffer fork  brace or perhaps a suspension
hub and a rebuilt wheel (e.g. fork brace - $90; hub -  $80;
rebuild - $100.  Plus the original $350 for the fork.  YMMV).

6)  Better "feel".  The stem allows you to have a rigid fork,
which transmits more "information" back to the rider.  This is a
benefit when riding through creeks where you cannot see where
your wheel is.

7)  Less exposed to the environment.  The stem is higher, more
out of the way than suspension forks.  Thus you can ride through
creeks and mud without having to worry about your fork seals, or
about contaminating the innards of the fork.  Even if mud
splashes on a suspension stem, the pivots are less sensitive to
grit than sliders and stanchion tubes.

8)  Ease of maintenance.  There are no seals to replace or
service, no oil to replace, no air pressure to adjust, and no
bumpers to wear out.  An occasional lube of the pivots is all
that is needed.  An extension of this is the ease of initial set
up.  For best results, you have to set suspension (fork or stem)
to react according to your weight and riding style.  With air/oil
forks you may have to change oil, adjust pressure or change
damping settings (if the fork has them).  With bumper forks you
may need to swap out bumper stacks and mix-n-match bumpers until
you get what works for you.  With the stem, the only adjustment
is to increase or decrease the spring tension with an allen


1)  No damping.  This is one of the main complaints from
proponents of suspension forks.  The suspension stem will give
way to absorb shock, but the return is not controlled and cannot
be adjusted.  JP Morgen currently makes a suspension stem which
employs oil-damping, but Allsop does not.

2)  Requires adjustment to riding style.  As mentioned above, the
stem requires weight to be applied to it to function.  This is
also one of the complaints applied to the Softride rear
suspension beam.  The flip-side to this, according to riders of
the Beam, is once the adjustment is made to "plant your butt on
the saddle" the ride is extremely comfortable and affords
excellent control by sticking the rear tire to the ground.

3)  Stem "clunks" on rebound.  The feeling is about the same as
suspension bottoming out, except it happens on the rebound.  This
is not as much a problem on the Allsop as on the Morgen stem,
which uses a hard plastic top-out bumper.  This is a subjective
complaint, as some riders claim not to notice it.

4)  Stem not torsionally rigid.  Another trade off.  The stem is
not proof to twisting forces and may be noticeable in hard,
out-of-the-saddle efforts.  Allsop has redesigned the top beam of
their aluminum stem for 1994 to address this problem.  Instead
of the aluminum "dog bone" structure for the top linkage member,
they've substituted a machined aluminum beam, reminiscent of a
cantilever bridge.

SUMMARY:  In my opinion, a suspension stem is an excellent choice
if one is retrofitting an existing bike, which has not been
designed around a suspension fork.  A suspension stem is also a
very good choice if one's primary riding is twisty singletrack,
where you need the sharp, precise steering of a rigid fork.
There are undoubtedly situations for which a stem may not be
ideal, but stems should not be dismissed as a viable form of
suspension.  The best thing to do is to try both types of
suspension if you can, and see what you like better.


Subject: 10.2  MTB FAQ available
From: Vince Cheng <vccheng@gpu.srv.ualberta.ca>

I have written a MTB FAQ.  It's available from:


or you can email me at the above address for a copy.


Subject: 10.3  Installing new rear derailleur spring
From:    Alan C Fang <jsbach@uclink2.berkeley.edu>
Date:    Tue, 20 May 1997 12:27:07 -0700 (PDT)

leave the derailler on the bike.  first, check the orientation of the old
spring so that you will know how to put in the new one.  taking out the
old spring shouldn't be too hard- just yank on it.  if you can't do it,
use the reverse of what i'm about to tell you for getting the new spring

one end of the spring is open.  that open end has to hook onto this bar on
the derailler body. to get it up and over this bar, get a piece of brake
or shifter cable (or a strong string) and bend it in half, putting a kink
in it.  put the spring inside the derailler in the proper orientation.
thread this kink through the derailler where the bar is, making it go on
the side of the bar opposite the open side of the spring's hook.  hook the
kink in the cable around the open end of the spring, and yank on the
cable.  that should pull the open end of the spring past the bar.  now you
can stuff the tip of the hook back over the bar, thus hooking the
derailler spring onto the bar.

the closed end of the spring is much easier to get in.  what i use is a
bottom bracket tool, the kind with the pins for adjusting older style
bb's. use one of the pins to grab the closed end of the spring, and lift
it up so that it hooks onto that [other thing]. you are done.  voila!  or
as a dyslexic would say, viola!


Subject: 10.4  A Brief History of the Mountain Bike
From:    Jobst Brandt <jbrandt@hplabsz.hpl.hp.com>
Date:    Mon, 13 Oct 1997 15:02:23 PDT

The first -successful- high quality fat-tire bicycle was built in
Marin County, California by Joe Breeze, who with others rode down the
rocky trails of nearby My Tamalpais.  They used balloon-tire one-speed
clunkers from the 1930s, 1940s and 1950s (Schwinn Excelsior) to
descend these trails with coaster brakes.  In that pursuit, one of
these trails got the name "Repack" because one descent was enough to
vaporize the brake's grease, requiring the hub to be re-packed.

Joe Breeze, Otis Guy, and Gary Fisher, all still in the bike business
today, were top category USCF riders.  Many of the Tamalpais riders
were members of road club Velo Club Tamalpais, wearing a blue and gold
jersey with the mountain logo.  In October of 1977, Joe built a
fat-tire bike of lightweight tubing that was previously found only on
better road bikes.  It had all new, high-quality parts and 26" x
2.125" Uniroyal "Knobby" tires on Schwinn S2 rims and Phil Wood hubs.
Joe built ten of these first Breezers by June 1978.  Breezer #1 has
been on display at various places, including the Oakland Museum, where
it has been on permanent display since 1985.

However the first Breezer was predated by a frame built for Charlie
Kelly by Craig Mitchell earlier in 1977.  As the Breezer frames that
followed, it was made of 4130 chrome-moly airframe tubing.  Kelly
equipped it with the parts from his Schwinn Excelsior.  These parts
included SunTour derailleurs and thumbshifters, TA aluminum cranks,
Union drum brake hubs, motorcycle brake levers, Brooks B-72 saddle,
Schwinn S-2 rims and UniRoyal Knobby tires (essentially, the best
parts found on clunkers of that day).  In spite of this, Charlie chose
switch back to his Schwinn frame, which he rode until June of 1978,
when he got himself a Breezer, and for one reason or another the
Mitchell frame was not further developed.

In January 1979, Joe and Otis, who were planning another
transcontinental record attempt, visited Tom Ritchey, who was building
their tandem frame, and brought along Joe's Breezer mountain bike.
Peter Johnson, another noted frame builder who happened to be present,
was immediately impressed with its features, as was Tom who also
sensed the significance of the concept, being a veteran road bike
trail rider in the Santa Cruz mountains.  Gary Fisher got wind of
Tom's interest in fat tire bikes and asked Tom to build him one.  Tom
built one for himself, one for Gary, and one for Gary to sell.

After building nine more frames later in 1979, Tom couldn't find
buyers for them nearby in Palo Alto, so he asked Fisher if he could
sell them in Marin.  Fisher and Charlie Kelly pooled a few hundred
dollars and started "MountainBikes" which became today's Gary Fisher
Bicycles.  It was the first exclusively mountain bike business.  It
was Tom's bikes, and Fisher and Kelly's business that made the
introduction of the mountain bike take hold.  There was an obvious gap
in the market, most builders focusing on road bikes left this an open
field for innovation.

If anyone's name stands out as the builder of the earliest viable
mountain bike, it is Joe Breeze, who today still produces Breezers.
The marketing push first came from Tom Ritchey, Gary Fisher, and
Charlie Kelly and the ball was rolling.  At first the USCF felt it
below their dignity, as did the UCI, to include these bicycles, but
after NORBA racers began to outnumber USCF racers, they relented and
absorbed these upstarts, as they certainly would recumbents if they
had similar public appeal.


Subject: 10.5  The Mike Vandeman FAQ
From: Dave Blake <dblake@phy.ucsf.edu>
Date: Tue, 29 Jul 1997 20:49:05 PDT

Michael Vandeman has been posting to the bicycling and environmental
newsgroups (among others) for years about various topics some of which are
covered below. This FAQ is not intended to do anything other than to
collect the frequently asked questions and rebuttals and hold them all in
one place so that bandwidth can be reduced. Each article is written by
someone in one of the newsgroups afflicted with Vandemanism, and as such
should be considered the opinions only of the parties quoted in the
article. However, to reduce bandwidth, one should read the FAQ before
replying to Vandeman. If his post is covered in the FAQ adequately, please
at most post a pointer to the FAQ URL so that everyone can read it. If the
FAQ does not adequately cover the point, by all means post your own reply.
You may want to consider emailing me a rewritten article for the FAQ to
make it more complete.

The Mike Vandeman FAQ is available at: