MTB front suspension systems still in production...

Discussion in 'Cycling Equipment' started by Simon Brooke, Dec 22, 2003.

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  1. Simon Brooke

    Simon Brooke Guest

    I am, mainly for my own education and amusement, doing a little bit of research into MTB front
    suspension systems.

    The mainstream conventional system of course is the dual sliding stanchion fork with the sliders at
    the bottom. I can remember from about thirty years ago a detailed technical article by a British
    motoring journalist who wrote as LJK Setright (it may even have been his real name) on motorcycle
    suspension in which I recall that he concluded, for apparently convincing reasons, that for
    motorcycles anyway this was the worst possible design (mainly as I recall due to poor stiffness).

    I can track down still in production

    * Dual sliding stanchion with sleeves at the bottom (90% of the market)

    * Dual sliding stanchion with sleeves at the top (Maverick)

    * Unequal length leading link (Whyte)

    * Monoblade sliding stanchion with the sleeve at the top (Cannondale)

    * USE Sub - a monoblade with what may technically be a leading link, although the geometry appears
    quite different from other leading links

    * In head tube (Cannondale again).

    I can't find anyone still marketing an equal-length-link fork, although I saw such a thing for sale
    on eBay not long ago. I know AMP used to make one, and I know there were leading link forks produced
    by Joe Murray and by Matt Lawwill(?sp) but I can't find any pictures of either so I don't know
    whether the links were equal length.

    I'm also aware of other 'sleeve at the top' dual stanchion designs in the past (Halston and
    Suspenders) and another in-headtube designs (Action Tec).

    What have I missed?

    Why did the equal-length-link fork die?

    Which of these designs do you consider better than the 'sleeve at the bottom' dual stanchion
    design, and why?

    --
    [email protected]e.org.uk (Simon Brooke) http://www.jasmine.org.uk/~simon/

    'graveyards are full of indispensable people'
     
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  2. S. Anderson

    S. Anderson Guest

    Some notes from my cluttered mind..

    "Simon Brooke" <[email protected]> wrote in message
    news:[email protected]...
    > I am, mainly for my own education and amusement, doing a little bit of research into MTB front
    > suspension systems.
    >
    > The mainstream conventional system of course is the dual sliding stanchion fork with the sliders
    > at the bottom. I can remember from about thirty years ago a detailed technical article by a
    > British motoring journalist who wrote as LJK Setright (it may even have been his real name) on
    > motorcycle suspension in which I recall that he concluded, for apparently convincing reasons, that
    > for motorcycles anyway this was the worst possible design (mainly as I recall due to poor
    > stiffness).

    There are several disadvantages to the dual stanchion fork: somewhat poorer stiffness, stiction,
    brake dive to name a few.

    >
    > Joe Murray and by Matt Lawwill(?sp) but I can't find any pictures of

    His name was Mert Lawwill. He made the leader fork and it was a four leading link design. See photo
    here http://www.bikepro.com/products/forks/lawill_index.html.

    >
    > I'm also aware of other 'sleeve at the top' dual stanchion designs in the past (Halston and
    > Suspenders) and another in-headtube designs (Action Tec).

    'sleeve at the top' is referred to generally as "upside down forks". "Right way up" being the slider
    on the bottom style.

    > Why did the equal-length-link fork die?

    I'm not sure it's dead entirely..there might still be a few makers around.

    > Which of these designs do you consider better than the 'sleeve at the bottom' dual stanchion
    > design, and why?

    I can't say for sure with bicycles, but in motorcycles, the dual stanchion design is still king.
    There are some link design front suspensions (BMW and Honda both have them..) but racing bikes still
    prefer the old-style forks. I believe they prefer the feel of those forks and the steering feel.
    They actually LIKE the brake dive and accompanying geometry change as a method to get the bike to
    turn in quickly but not be too steep during straight-line riding. I also suspect they are well
    refined and understood better than the newer link designs.

    Cheers,

    Scott..
     
  3. Carl Fogel

    Carl Fogel Guest

    Simon Brooke <[email protected]> wrote in message news:<[email protected].uk>...

    [snip]

    Dear Simon,

    The last picture that I can find of leading-link or springer forks in the observed trials world is
    in the 1969 "Sammy Miller on Trials," where Gordon Jackson is shown plunging into a bog up to his
    front hub on a Greeves Anglian.

    About the same time, the dual-range gearbox Honda Trail 90 with leading link forks turned into a
    110cc bike and switched to telescopic forks.

    Apart from their exposed complexity, leading-link forks gave far less travel, as I recall. Off-road,
    travel mattered far more than preserving precise steering geometry.

    Since early mountain bikes probably imitated off-road motorcycles, they would have been unlikely to
    adopt a discarded front suspension scheme.

    As for the upside-down forks, one of their advantages, apart from stiffer upper parts, is that they
    reduce unsprung weight--the smaller diameter lower tubes that the suspension has to move are
    lighter, which is important in motorcycles, where the front wheel and its suspension outweigh an
    entire road bicycle.

    Carl Fogel
     
  4. Eric M

    Eric M Guest

    In article <[email protected]>,
    Carl Fogel <[email protected]> wrote:
    >Simon Brooke <[email protected]> wrote in message
    >news:<[email protected]>...
    >
    >[snip]
    >
    >Dear Simon,
    >
    >The last picture that I can find of leading-link or springer forks in the observed trials world is
    >in the 1969 "Sammy Miller on Trials," where Gordon Jackson is shown plunging into a bog up to his
    >front hub on a Greeves Anglian.

    But the Greeves that won the Scottish Six Days in '69 ridden by Bill Wilkinson was using a Metal
    Profile telescopic front fork.

    Alternative front ends have appeared in the off-road motorcycle world occasionaly since then.
    Roger Decoster raced an MX bike with a sprung girder front end that gave 13 inches of travel(!) in
    the late 70s.

    Modern MX bikes use about 11 inches of travel; more than that results in too much of a geometry
    change. Modern trials motorcycles use about 7 inches. Trials motorcycles are getting very light; the
    lightest (Gas Gas Adam Raga replica) is at 139 lbs. At the rate that trials bikes are getting
    lighter and mountain bikes are getting heavier and more motorcycle-like I expect them to meet in
    about three years. (actually its already happened; some french guy set a 125mph downhill speed
    record in the mid 90s on a mountain bike built from a Yamaha TYZ trials bike chassis. The bike was
    built by Bernie Schreiber, the only American world trials champion).

    Eric
     
  5. Carl Fogel

    Carl Fogel Guest

    "Eric M" <[email protected]> wrote in message news:<[email protected]>...
    > In article <[email protected]>, Carl Fogel
    > <[email protected]> wrote:
    > >Simon Brooke <[email protected]> wrote in message
    > >news:<[email protected]>...
    > >
    > >[snip]
    > >
    > >Dear Simon,
    > >
    > >The last picture that I can find of leading-link or springer forks in the observed trials world
    > >is in the 1969 "Sammy Miller on Trials," where Gordon Jackson is shown plunging into a bog up to
    > >his front hub on a Greeves Anglian.
    >
    > But the Greeves that won the Scottish Six Days in '69 ridden by Bill Wilkinson was using a Metal
    > Profile telescopic front fork.
    >
    > Alternative front ends have appeared in the off-road motorcycle world occasionaly since then.
    > Roger Decoster raced an MX bike with a sprung girder front end that gave 13 inches of travel(!) in
    > the late 70s.
    >
    > Modern MX bikes use about 11 inches of travel; more than that results in too much of a geometry
    > change. Modern trials motorcycles use about 7 inches. Trials motorcycles are getting very light;
    > the lightest (Gas Gas Adam Raga replica) is at 139 lbs. At the rate that trials bikes are getting
    > lighter and mountain bikes are getting heavier and more motorcycle-like I expect them to meet in
    > about three years. (actually its already happened; some french guy set a 125mph downhill speed
    > record in the mid 90s on a mountain bike built from a Yamaha TYZ trials bike chassis. The bike was
    > built by Bernie Schreiber, the only American world trials champion).
    >
    >
    > Eric

    Dear Eric,

    Here's a Greeves site showing one the last of the leading-link fork Anglian monsters in action in
    1967 in color:

    http://home.earthlink.net/~frank1328/history.htm

    Next to it is a black-and-white of the 1967 Anglian with a telescopic fork, and above this is the
    Greeves Scottish Trials 1962-1964 model, showing its leading link.

    Here's Roger DeCoster's weird 1979 Ribi leading-link fork with its enormous travel allowed by its
    peculiar design, something that might interest Simon Brooke:

    http://www.off-road.com/rick/remember

    Note that there are links both behind and in front of the shock-absorber and coil-spring unit, said
    links being hinged near the bottom as vaguely explained later.

    The Ribi link-fork design is mentioned here:

    http://www.eric-gorr.com/techarticles/future_biketech.html

    "The link forks were tested by Honda via Roger DeCoster and an engineer from Brazil named Ribi. The
    Ribi forks consisted of aluminum extrusions designed for rigidity. A single shock was mounted via
    conventional shock linkage, to the triple clamp. The forks were rising rate and worked like a
    conventional fork in that they compressed when you apply the front brake. Older leading link forks
    work opposite meaning that the front end extended when the front brake was applied. That was great
    on down-hills but very scary in turns! The Ribi fork design never made it in mx but it was later
    adapted for roadracing and used with great success on the Britten, a bike made in New Zealand."

    Alas, I found nothing on the Britten web site about anything except telescopic forks.

    Another web site has this description of the odd Ribi fork on a 1987 Honda, claiming that it was a
    Belgian rather than a Brazilian design:

    http://www.slack.net/~thundt/Bmw/bikeshad.txt

    "Honda RC370 "Ribi Fork" - Roger DeCoster rode this bike in several championship races; the exotic
    fork design was purchased from a Belgian designer by Honda and made for the 500 class bike. It had
    three separate sections that hinged, folding up as the wheel went through its travel. Last time I
    saw it, it was on display in Honda's Dallas Zone office. I think only one or two were ever made."

    All the pictures show one other leading-link drawback for trials bikes--the front fenders were
    always mounted up high, an abomination that obscured the front tire.

    Carl Fogel
     
  6. "Simon Brooke" <[email protected]> wrote in message
    news:[email protected]...
    > I am, mainly for my own education and amusement, doing a little bit of research into MTB front
    > suspension systems.
    >
    > The mainstream conventional system of course is the dual sliding stanchion fork with the sliders
    > at the bottom. I can remember from about thirty years ago a detailed technical article by a
    > British motoring journalist who wrote as LJK Setright (it may even have been his real name) on
    > motorcycle suspension in which I recall that he concluded, for apparently convincing reasons, that
    > for motorcycles anyway this was the worst possible design (mainly as I recall due to poor
    > stiffness).
    >
    > I can track down still in production
    >
    > * Dual sliding stanchion with sleeves at the bottom (90% of the market)
    >
    > * Dual sliding stanchion with sleeves at the top (Maverick)
    >
    > * Unequal length leading link (Whyte)
    >
    > * Monoblade sliding stanchion with the sleeve at the top (Cannondale)
    >
    > * USE Sub - a monoblade with what may technically be a leading link, although the geometry appears
    > quite different from other leading links
    >
    > * In head tube (Cannondale again).
    >
    > I can't find anyone still marketing an equal-length-link fork, although I saw such a thing for
    > sale on eBay not long ago. I know AMP used to make one, and I know there were leading link forks
    > produced by Joe Murray and by Matt Lawwill(?sp) but I can't find any pictures of either so I don't
    > know whether the links were equal length.
    >
    > I'm also aware of other 'sleeve at the top' dual stanchion designs in the past (Halston and
    > Suspenders) and another in-headtube designs (Action Tec).
    >
    > What have I missed?
    >
    > Why did the equal-length-link fork die?
    >
    > Which of these designs do you consider better than the 'sleeve at the bottom' dual stanchion
    > design, and why?
    >
    >
    > --
    > [email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/
    >
    > 'graveyards are full of indispensable people'

    my only comment would be that the Cannondale ones aren't "sliding" systems. No bushings, all roller
    bearings; but you knew that already....
     
  7. Jim Beam

    Jim Beam Guest

    as far as the bottom sliders are concerned, you also need to consider manufacturing route. one side
    usually has the spring, the other the damper. for that reason, and the fact that the wheel needs to
    stay square, i'd say the "disadvantages" of bottom slider are small.

    regarding the main argument against bottom sliders, mass, these are, from what i can see, small
    compared to sticktion. i've had a marzocci x2, psylo and fox talas. with the first two, you may have
    been able to tell me that mass was a factor because the ride, while fine, was not perfect cornering
    on loose terrain. you could have told me that reaction time of higher mass affected the wheels
    ability to track the terrain. but riding the fox *crushes* that assumption. it is so far superior to
    anything else i've ever ridden, while still being no lightweight, it seems to me that sticktion and
    proper damping are the biggest factors. if fox are able to get both those factors right, and it
    takes a bottom slider to do it, then i'm happy with the compromise!

    jb

    Simon Brooke wrote:
    > I am, mainly for my own education and amusement, doing a little bit of research into MTB front
    > suspension systems.
    >
    > The mainstream conventional system of course is the dual sliding stanchion fork with the sliders
    > at the bottom. I can remember from about thirty years ago a detailed technical article by a
    > British motoring journalist who wrote as LJK Setright (it may even have been his real name) on
    > motorcycle suspension in which I recall that he concluded, for apparently convincing reasons, that
    > for motorcycles anyway this was the worst possible design (mainly as I recall due to poor
    > stiffness).
    >
    > I can track down still in production
    >
    > * Dual sliding stanchion with sleeves at the bottom (90% of the market)
    >
    > * Dual sliding stanchion with sleeves at the top (Maverick)
    >
    > * Unequal length leading link (Whyte)
    >
    > * Monoblade sliding stanchion with the sleeve at the top (Cannondale)
    >
    > * USE Sub - a monoblade with what may technically be a leading link, although the geometry appears
    > quite different from other leading links
    >
    > * In head tube (Cannondale again).
    >
    > I can't find anyone still marketing an equal-length-link fork, although I saw such a thing for
    > sale on eBay not long ago. I know AMP used to make one, and I know there were leading link forks
    > produced by Joe Murray and by Matt Lawwill(?sp) but I can't find any pictures of either so I don't
    > know whether the links were equal length.
    >
    > I'm also aware of other 'sleeve at the top' dual stanchion designs in the past (Halston and
    > Suspenders) and another in-headtube designs (Action Tec).
    >
    > What have I missed?
    >
    > Why did the equal-length-link fork die?
    >
    > Which of these designs do you consider better than the 'sleeve at the bottom' dual stanchion
    > design, and why?
     
  8. Simon Brooke

    Simon Brooke Guest

    "NICHOLAS CHILDS" <[email protected]> writes:

    > "Simon Brooke" <[email protected]> wrote in message
    > news:[email protected]...
    > > I can track down still in production
    > >
    > > * Dual sliding stanchion with sleeves at the bottom (90% of the market)
    > >
    > > * Dual sliding stanchion with sleeves at the top (Maverick)
    > >
    > > * Unequal length leading link (Whyte)
    > >
    > > * Monoblade sliding stanchion with the sleeve at the top (Cannondale)
    > >
    > > * USE Sub - a monoblade with what may technically be a leading link, although the geometry
    > > appears quite different from other leading links
    > >
    > > * In head tube (Cannondale again).
    >
    > my only comment would be that the Cannondale ones aren't "sliding" systems. No bushings, all
    > roller bearings; but you knew that already....

    Well, I ride a Lefty-equipped Cannondale myself, so yes I do know it runs on roller bearings... this
    doesn't feel to me a fundamental difference. Do you disagree? Where both Cannondale systems differ
    from the conventional is that the inner part is constrained from rotating in the outer, which might
    be seen as a fundamental difference.

    --
    [email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/ ;; Generally Not Used ;;
    Except by Middle Aged Computer Scientists
     
  9. "Simon Brooke" <[email protected]> wrote in message
    news:[email protected]...
    > "NICHOLAS CHILDS" <[email protected]> writes:
    >
    > > "Simon Brooke" <[email protected]> wrote in message
    > > news:[email protected]...
    > > > I can track down still in production
    > > >
    > > > * Dual sliding stanchion with sleeves at the bottom (90% of the
    market)
    > > >
    > > > * Dual sliding stanchion with sleeves at the top (Maverick)
    > > >
    > > > * Unequal length leading link (Whyte)
    > > >
    > > > * Monoblade sliding stanchion with the sleeve at the top (Cannondale)
    > > >
    > > > * USE Sub - a monoblade with what may technically be a leading link, although the geometry
    > > > appears quite different from other leading links
    > > >
    > > > * In head tube (Cannondale again).

    > > my only comment would be that the Cannondale ones aren't "sliding"
    systems.
    > > No bushings, all roller bearings; but you knew that already....

    > Well, I ride a Lefty-equipped Cannondale myself, so yes I do know it runs on roller bearings...
    > this doesn't feel to me a fundamental difference. Do you disagree? Where both Cannondale systems
    > differ from the conventional is that the inner part is constrained from rotating in the outer,
    > which might be seen as a fundamental difference.

    I think the removal of stiction is important and while Lefty's and Headshoks have been tested to
    have less flex it's hard to determine whether this is due only to the use of roller bearings or
    better engineered materials overall. 'Shocks' aren't that complicated - spring, damper, and relative
    movement system(telescoping, linkage, etc.). Do any motorcycle manufacturers use roller bearings?
    Perhaps the use of larger diameter stanchions minimises stiction and flex for a lower weight
    penalty? Maybe the bushings are replaceable?

    Nick
     
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