Recently I was chatting to a rider on my local trails who said something that really got me thinking: "A 120mm-bike is really the ideal bike for UK riding, isn't it?"
Is it? Mike Levy made the case for short-travel bikes back in 2012
, and the popularity of this sentiment seems to have grown recently. I'm not trying to rain on anybody's parade; there's no doubt that short-travel bikes have got a lot more capable in recent years, and if you like riding downhill on your downcountry bike then great. But it seems that for some people, under-biking is a badge of honour while over-biking (riding an unnecessarily long-travel bike) is something to be ashamed of. Some see long-travel bikes as a comfort blanket or a one-trick pony - a bad choice for anyone who isn't racing an EWS stage. My view is that long-travel bikes are actually the more versatile option. They don't need to be a slog on mellower trails or when climbing, and they are just better when the trail gets nasty.More travel, more options
Going back to that rider's comment, there is plenty of rowdy terrain in the UK, and even here in the Wye Valley where our conversation took place. But as for the flowy trail we'd just ridden, I could see his point - you really don't need
more than 120mm of squish to ride it comfortably, and nobody wants a bike that feels like a soft mattress when pumping through fast, smooth berms.
But you don't have to use all of your travel all the time. In fact, you don't have
to use all your travel... ever. I think some people take the often-repeated advice that you should set your bike up with about 30% sag and bottom-out once per ride too seriously. If you want a more responsive feel from your long-travel bike, there's nothing to stop you from trying less sag, more compression damping or more volume spacers (even if it means you never use full-travel). Just flicking the climb switch will close the gap to a short-travel bike when pumping smooth terrain. But if you wanted to make a short-travel bike softer and more forgiving, you'd soon run out of travel. In other words, you can make a long-travel bike firmer and more responsive, but you can't make a short-travel bike softer and more forgiving.Bad vibrations
But there's a good reason most people want to make use of all the travel they've got: harshness. There's precious little scientific data in the mountain bike world, but this study from Edinburgh Napier University
is a rare exception. Two elite-level athletes raced two UK enduro races each, riding either a 27.5" bike with a 170mm fork or a 29er with a 160mm fork. They had accelerometers fitted beside the grips which revealed levels of vibration that exceed safety limits set for industrial workers using equipment like jackhammers and chainsaws.
How bad is that? The study's lead author, Lewis Kirkwood, says "I don't want to cause panic"..."but it's concerning".
Here's how it's put in the study: "elite enduro mountain bike athletes are exposed to potentially harmful levels of hand-arm vibration ... prolonged or repeated exposure to such levels of vibration could potentially lead to the development of vibration-related pathologies such as ulnar nerve compression or HAVS [hand-arm vibration syndrome]".
This test was on enduro stages, which are probably rougher than your average ride. But both riders were using relatively long-travel bikes, so it stands to reason that riders could be receiving similar levels of vibration on less extreme terrain when riding a shorter-travel bike with stiffer suspension. And of course, this concern that vibration could lead to long-term pathologies is just another reason why you might prefer softer suspension - traction, confidence on technical terrain and in-the-moment comfort are still very
good reasons.A good deal
Bike design and bike choice largely come down to the trade-off between climbing performance against descending performance. Increasing travel means gaining a lot on the descents without necessarily giving much up on the climbs.
Sure, longer travel bikes tend to be heavier, but it's not the travel itself that adds weight, but the heavier components which long-travel bikes tend to be paired with. A 180mm RockShox Lyrik weighs the same as the 150mm version, and a 170mm-travel Nukeproof Giga frame weighs just 280g more than a 130mm-travel Nukeproof Reactor
And while long-travel bikes used to pedal like a bouncy castle, there are plenty of long-travel bikes these days which have very little pedal-bob thanks to clever use of anti-squat
, which controls suspension movement when pedalling. There are also lockouts or climb switches, which allow any bike to pedal more efficiently at the flick of a switch
. More travel doesn't have to mean a reduction in climbing efficiency. With well-designed suspension and steep seat angles, some modern enduro bikes are really good climbers.
Which of these bikes is the more efficient climber? According to Levy's version of science, it's the 170mm-travel Nomad.
In last year's efficiency test
, the 170mm-travel Santa Cruz Nomad climbed faster than the 130mm-travel Ibis Mojo (at the same power), and the 180mm-travel Propain Spindrift wasn't far behind - that's despite the longer travel bikes being fitted with slower-rolling tires and all of the shocks were fully open. So, even if you can't bring yourself to use that "cheater switch" (lockout), some long-travel bikes are so efficient these days that you can have your cake and eat it too.
But when descending, there's no replacement for displacement. A short-travel bike will never deal with rough terrain as deftly as a well-set-up long-travel bike because the vertical wheel travel fundamentally limits how much the suspension can absorb before the frame starts moving upwards into the rider.
The crux of my argument is that there's an asymmetry here: a long-travel bike can climb like a short-travel bike if the suspension is designed well, but there's no way to make a short-travel bike absorb bumps like a long-travel bike. It's just not possible. Suspension travel is one of the most important factors when descending, but one of the least important when climbing.The original short-travel troublemaker
The Kona Process 111
was a pretty interesting bike when it launched in 2013. What made it stand out in my view was the relatively long reach, short stem and short-offset fork, which together made it among the best handling 29ers of its day. But I rode one as a long-term test bike for a year and its defining feature (the 111mm of travel) was the worst thing about it.
Most reviews pointed out that it descended surprisingly well for its travel. I agree, but that's not the right question. A better question is does it descend well relative to how it climbs? The answer is no.
The bike I had weighed 16Kg (35lb) and had an effective seat angle of 73-degrees at my pedalling height. The suspension (which had very little anti-squat and no lockout) bobbed quite a lot when pedalling too, even when compared to longer-travel bikes. And while it handled well, it soon became brutal as the trails got faster and rougher. Even bikes of the time like the original Specialized Enduro 29 climbed just as well (if not better) and was much less limiting when the descents got gnarly.Conclusion
The recent down-country trend has made a lot of people realise how much you can do with a small amount of travel. But it's also worth keeping in mind how capable long-travel bikes have become uphill. There's a lot of flexing to be done by sending it on your 120mm-bike, less so by bossing a climb on your 180mm bike. But when it comes to the balance of climbing vs descending, the long-travel route makes way more sense. It's easier to make a long-travel bike that climbs well than a short-travel bike that desends well.
Don't get me wrong - I see the appeal of super-light cross-country and downcountry bikes for all-out speed and efficiency; I love the idea of donning Lycra and chewing up singletrack on a Transition Spur
or Scott Spark
. But I see more and more short-travel bikes being used as do-it-all bikes, often fitted with coil shocks, hefty tires and inserts in an attempt to make up for the lack of travel. If you want one bike to do everything, I think it makes more sense to have a capable long-travel bike that can be fitted with faster-rolling tires (and even stiffer suspension settings) for mellower rides.
I'm sure I'll get plenty of pushback in the comments for this so let me know if you agree or if I'm missing the point.