In the first part of this buyer’s guide we explained some of the theory behind mountain bike suspension. This time we’re looking at six of the most common frame designs and discussing which is best. Next week we’ll look at suspension forks and rear shocks.
There are many rear suspension designs, and they all have slightly different traits. Some feel plusher than others, but the plush feel can desensitise your riding. Frames that feel ﬁrmer often feel faster and livelier. Some designs, such as single pivots, can have more ﬂex than other bikes, but a little ﬂex can be good as the bike can contort slightly through rough terrain.
Designs using cartridge bearings may be ultra plush, but they carry a weight penalty – bushings can be as efﬁcient and weigh less, so they have their place. It can be tricky ﬁnding the right bike to suit you – the best way is to test ride as many different types as you can. Here’s a quick guide to the six most common frame layouts:
1 Single pivot
- Examples: Orange 5, Santa Cruz Heckler, Santa Cruz Bullit, Diamondback XSL Comp.
- Pros: Simple, minimal pivots, light weight, reduced pedal bob.
- Cons: Prone to pedal feedback and interference from braking forces.
- Buy if: You’re worried more about long-term durability than a more reﬁned suspension feel. This is the least technically demanding suspension platform so it’s ideal for the tool shy.
2 Faux bar
- Examples: Kona Dawg, Ventana El Ciclon, Scott Spark.
- Pros: Fairly light, low pedal kickback.
- Cons: Prone to bobbing and braking forces.
- Buy if: You like to ride hard and fast. Ideal on hard-hitting trail bikes where absolute subtlety isn’t a major concern – what it lacks in sensitivity it makes up for in direct drive feel. More pivots means it needs more regular checking.
3 Standard four bar
- Examples: Specialized FSR Stumpjumper, Boardman FS, Ellsworth Epiphany.
- Pros: Fairly light, limited pedal kickback, improved suspension under braking.
- Cons: Pedal bob. Requires regular pivot checks.
- Buy if: You want better suspension action under braking than single pivot and faux bar bikes; harder, faster trail riders like this design as it allows you to attack the trail without losing rear wheel traction.
4 Twin link four bar
dw-link: Like the VPP system, Dave Weagle’s dw-link design uses twin links to isolate the rear end, but the axle path and characteristics differ from VPP. The heart and soul of the dw-link is the anti-squat curve. The Weagle design speciﬁcally alters the amount of anti-squat through the travel from where he thinks you need it most, at the start, to where you need it least, deep in the travel where you are less likely to be pedalling.
This upshot of this is that pedal kickback can be reduced while still maintaining a good pedalling performance. This is coupled with precisely tuned leverage ratios in an attempt to make the bike remain fully active in the majority of conditions and gears. A few manufacturers have their own take on this setup with varying degrees of performance, and even the dw-link itself alters according to the type of bike it is on. Examples: Turner Flux, Ibis Mojo, Pivot Mach 5.
Other: Both Giant with their Maestro system and Marin and Whyte with their Quad Link systems use variations on the twin-link four bar theme. Examples: Giant Anthem and Trance, Marin Mount Vision, Whyte E120.
- Pros: Can offer good braking, pedalling and pedal kickback performance.
- Cons: Above pros depend on precise setup, is relatively heavy.
- Buy if: You want a supple ride with a strong climbing capability. Riders of mid- and long-travel trail/all-mountain bikes love the clean feel of the stop/go action for its terrain-eating ability, but it needs careful shock setup to work optimally.
5 Active Braking Pivot (ABP)
- Examples: Trek Fuel EX, Trek Remedy, Gary Fisher Roscoe.
- Pros: Low pedal kickback, very good under braking.
- Cons: Pedal bob, needs unique rear skewer for axle.
- Buy if: You like how faux bars and single pivots ride but want the beneﬁt the ABP gives to retain a supple suspension action even with the rear brake fully on.
6 Floating drivetrain
One of the earliest types of full-suspension bike design was the Uniﬁed Rear Triangle. This incorporated the whole drivetrain on the swingarm, including bottom bracket, which was then attached to the main frame by a pivot. With no pedal kickback due to no chain extension, it was assumed this would offer the best of all worlds. But alas, with your weight on the swingarm when stood up, the performance varied signiﬁcantly depending on whether you were seated or standing and the design is little used nowadays.
However, GT and Mongoose with their i-Drive and Freedrive systems, and Maverick with the Monolink, have modiﬁed the concept to produce a range of ﬂoating drivetrain bikes where the bottom bracket is ﬁxed to a link between the front and rear triangles. The goal here is to try to combine the positive characteristics of more than one design.
While the axle path may be a simple arc like on a single pivot design, the bottom bracket itself moves as the suspension compresses. The relationship of the axle to the bottom bracket, and how the bottom bracket moves, produces different pedalling characteristics depending on the linkage setup.
- Examples: GT Sensor, Mongoose Teocali, Maverick ML8.
- Pros: Low pedal kickback, low bob, rearward axle path.
- Cons: Suspension efﬁciency can lessen when standing, heavy, affected by braking.
- Buy if: You want your suspension to be active across a wide range of terrain types and value traction sensitivity above all else. Again, careful shock setup and pivot care are needed to ensure performance.
So, which is the best?
None of them! Quite simply there’s no one design that’s better than another in all departments. And we have to remember the second part of the equation – the rider. Personal preference really is the key when it comes down to what works best for you.
Sure, many poor designs have faded from the scene, but what we’re left with nowadays is a variety of high performing machines that allow us to choose the very best for our needs. And given that the winners on the racing scene use a mix of machinery from the most basic to the very complex, it reinforces that the rider is the most important part of the picture.
Steve Peat has won World Cup downhill races on a GT Lobo (Horst Link), GT i-Drive (ﬂoating drivetrain), Orange 222 (single pivot) and of course the Santa Cruz V10 (VPP). However, small tweaks to the setups to suit your personal riding style can make quite a big difference to how each design type rides.
Maybe you don’t really care about weight? Or a few extra pivots? Possibly you’ve never noticed pedal feedback, or bobbing isn’t something that concerns you. Perhaps you hate the way some bikes seem to be affected when you brake. Many people simply don’t notice some of these effects, while others are more sensitive. Whatever your cup of tea, there are enough designs out there for you to pick one that suits. Get out there and try ’em.
One of the reasons it’s so hard to say which full sus design is ‘the best’ is that many of them work in different ways in different gear combinations. Typically, a lot of systems are designed to work at their best in the most frequently used gears — middle ring up front, middle sprocket out back — and this is why you see so many main swingarm pivots located in line with the middle chainring.
If you test ride a bike, try it in all possible gear combinations. Many suspension systems tend to respond in a very different way when subjected to steep climbs with excessive granny ring pedal pressure. You’ll almost certainly experience different amounts of pedal feedback in different gears.
Your choice of rear shock will also have some bearing on the way your suspension system feels. Air shocks have become dominant on all but the hardest hitting downhill bikes and the cheapest superstore bikes, where steel coil shocks are still popular. But air shocks vary a lot too.
Cheaper full-suspension bikes will often come with preset compression and rebound damping, while more costly bikes have adjustable damping so that you can ﬁne-tune the responses of the shock, as well as tuning the basic weight-bearing feel according to how much air you add (you’ll need a proper shock pump for this, a tyre pump won’t do).
Most air shocks these days also come with some form of platform damping system. This is often adjustable on the better shocks and helps to stiﬂe unwanted shock movement caused by pedal forces and weight shifts, but may reduce the compliancy of the suspension over small bumps. A lot of shocks come with a lockout function too.