25 Years of MTB Suspension

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Mountain bikers today take it for granted that their bikes will come with front and rear suspension that is easy to set up, adjust and will work reliably with minimal maintenance. But the trail to get to where MTB suspension is today was long and hard. Cycling Malaysia looks at the development of mountain bike suspension.

At the dawn of modern mountain biking, over 40 years ago, when Joe Breeze was building the first true mountain bike frames, fitting them with 26” beach cruiser tyres and romping around the trails in Marin County, California, off road bicycle suspension design was rudimentary. Relying purely upon the tensile properties of chrome moly steel, the earliest mountain bikes featured oversized steel forks to absorb trail vibration, as well as the oversized low pressure tyres that were fitted. Every frame was a hard tail, and riders were required to use their legs and arms as suspension components, letting the bike jump up and down beneath them. There were drawbacks to this, of course. There is only so much ‘give’ you can design into a steel frame before the tubes behave like spaghetti, and a frame that doesn’t allow the tyre to track and follow the trail surface will soon lead to crashes and wash outs, which is what riding the earliest mountain bikes was like. You soon learned to read the trail’s surface, and were always actually aware of exactly how much traction you had available, especially on downhill corners. What was needed was a suspension system that would absorb the trail’s bumps and undulations, while keeping the tyres firmly planted on the trail for traction and braking.

Frame geometry went through a weird phase of long tubes, short tubes and any permutation in between.

Off road suspension was not a new thing for two wheelers. Motorcycles had been using them for decades. Riders had been taking bicycles off road since the dawn of cycling, when roads were basically horse trails. The earliest bicycles were stripped of everything unnecessary for stopping, along with any other form of superfluous protection such as wheel guards, and used for off roading, as it were. In the early 80s, rigid frames were all that were available for the serious MTB rider.

Moving on from the beach cruiser origins of the first real mountain bikes, manufacturers and component makers were struggling to make bikes that were compliant on the trail, but still strong enough to take abuse. Frame geometry went through a weird phase of long tubes, short tubes and any permutation in between. Wheelbases lengthened and shrank according to market demand and who was winning what race with which bike that weekend. Components went light, to heavy and back to light again. All this was in the pursuit of making a mountain bike that would actually handle well off road and going downhill. What was required was a suspension light enough to be fitted to the bicycle, strong enough to take the abuse of the trail, and compliant enough to be better than the standard steel fork. In the late 80s, an unsung genius named Doug Bradbury came up with the first practical mountain bike suspension design. Based on a system of elastomers, Bradbury’s design gave riders a couple of inches of suspension compliance at the front end. This gave rise to Manitou forks, a name many riders will recognise. Unleashed in the hands of John Tomac, mountain bike suspension was now the must have thing for off road riders.

At this point, in the early 90s, performance suspension specialists RockShox and Fox had been developing telescopic front sus- pension that was light enough and strong enough for MTB use. RockShox earned a lot of recognition when Ned Overend and Greg Herbold won their respective World Championships. This now meant that everyone wanted a mountain bike, either hardtail or full suspension. The big manufacturers recognised this, and a lot of research and development money was spent in producing suspension designs. This did not mean that every design worked, or was necessarily able to function in the manner in which it was intended. Cannondale and Trek were among the first to hit the mass market with suspension MTBs. While some of the designs were innovative, they weren’t so good in practice. The necessity of mass manufacture meant that just because something went ‘boing’, it wouldn’t necessarily do so on the trail. A lot of innovation came from the smaller, garage shop based guys like Richard Cunningham at Manitou, Horst Leitner with the 4 bar linkage design we today call “Horst Links” and Brent Foes’s work with long travel suspension frames that were designed from the outset to accommodate and work in conjunction with suspension.

Fast forward 10 years to early 2000, and materials technology and engineering have moved forward enough for telescopic forks to be the design of choice for front suspension, and coil over hydraulic shocks for the rear. Based on traditional shock absorber design, these worked by compressing a coil spring, and using oil moving through orifices in metal valves inside the shock or fork to control compression damping and rebound. These designs worked, and worked well. But riders wanted more. They wanted more travel, they wanted less weight, they wanted more suspension compliance and adjustability. It was at this time that air suspension began to make its appearance. Air is lighter than a coil spring, and easily adjustable by adding or subtracting the air pressure contained inside the shock, instead of having to swap out springs to obtain different

spring rates that affect compression. The market had by now streamlined itself in a few major players. While Fox and RockShox were leading the pack, with other manufacturers like Marzocchi, Suntour, and Manitou had similar offerings. RockShox’s Judy was the front end of choice for many racers while Fox had their air sprung Float. If you were more into descents, you defaulted to a Marzocchi 888.

At this point, the mountain biking world was undergoing an upheaval. The sport was beginning to schism into cross country (XC), trails and downhill riding.

This meant that each different division of the sport required its own specialised frames, suspension design and components. While some of these were more the result of clever marketing from some of the larger manufacturers, it was clear that a cross country rider wanted something different out of his ride than a downhiller. Manufacturers were quick to comply, quickly coming out with suspension frame designs that were either developed in house, or bought over from their designers. Some of the truly innovative designs that hit the market in the late 2000s were Cannondale’s Lefty single sided front fork, RockShox Pike and Reba, and Fox’s Talas. It was also at this time the market was settling into a preference for suspension travel. In the early days, forks typically gave 45 to  75mm of travel, and this was deemed a lot. Riders were only seen riding 3 figure suspensions at championship level, perhaps culminating in the Marzocchi Super Monster T, with 300 mm of travel, and designed for falling off mountains.

Now, with years of development behind them, manufacturers were settling into 3 distinct offerings. 100 mm for XC riding, 120 to 150 mm for trails and all mountain riders and 160 mm and above for the downhillers. Another innovations at this time included adjustable travel forks, that allowed the rider to tune the fork’s ride height according to riding conditions. This simplified things for frame makers, since they could now design specific frames for specific suspension performance. This also meant they could leverage on their marketing to make riders buy 3 bikes, when previously one bike could do most of everything, albeit not well.

Rear suspension design was also fertile breeding ground for innovative designers. Starting out as hard tails, some frames allowed a certain amount of flex in the stays, leading to them being termed as ‘soft tails’.

Taking a leaf from motorcycle frame design, eliminating the stays and turning them into a proper swingarm gave us the first full suspension mountain bikes. Adding a swingarm and suspension to the rear gave rise to an unwanted affliction called ‘pedal bob’, where the suspension bounces in reaction to the rider’s pedalling motion. To eliminate this, and allow the rear wheel to stay in contact with the ground, a few designs came to fore, each with their own set of advantages and compromises in design. Notable examples include single pivot designs, Virtual Pivot Point, a short linkage 4 bar design and used by Santa Cruz and Intense, Dave Weagle’s co-rotating “DW-Link” that reduces squat during pedalling and used by Ibis, Turner and Pivot Cycles, Dave Earle’s “Switch Link” as used by Yeti, that attaches an eccentric pivot to the swingarm and connecting it to the frame giving it a compact rear, Trek’s “Full Floater” that isolates the rear shock from the frame, and uses a system of short links and top actuation to give the rear suspension a more linear movement and Felt’s “Equilink”, utilising a six bar suspension design that uses a bone shaped bar to tie the upper and lower links in the rear suspension together.

Presently, there are a multitude of suspension types and components to suit any type of off road riding. Both Fox and RockShox are today acknowledged market leaders, with the lion’s share of both OEM supplied suspension as well as aftermarket upgrades being supplied by them. There are offerings in both air and coil suspension, with air based designs pushed towards the XC and trails end of the market, and the heavier and more robust coil spring designs for the downhill and jump market categories, where component and all up weight is not as much of an issue. The DT Swiss range of carbon bodied forks combine lightness and performance, based on early work done by United Kingdom company Pace.

Newcomers to the market include manufacturers such as X-Fusion, who are putting forward cost effective suspension components that are not cutting new ground, but giving riders value for money choices.

Taking a leaf from motorcycle frame design, eliminating the stays and turning them into a proper swingarm gave us the first full suspension mountain bikes.

 

There is a trend being slowly introduced into the market that more is better, and if you are riding 100 mm travel XC mountain bike, 120 mm is better. Bear in mind that a bicycle is only as good as the rider, and more travel doesn’t turn you into a better rider overnight. What today’s suspension designs and wizardry do is allow the rider to be faster, more efficient and more relaxed in the saddle, allowing them to enjoy the ride and develop their riding skills.

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