2 10月 2017
GET THE PERFECT COCKPIT FOR YOUR MTB STYLE
Mountain bike cockpits – bars and stems – have changed a lot in recent years. A ‘wide’ set of MTB handlebars has gone from 660mm all the way out to 800mm, while what’s considered ‘short’ for a stem has shrunk from around 70mm to 35mm. How do you make sense of such radical change? And what dimensions should you be running?
The answer depends on three things. First, and most importantly, you should simply be running what fits you. Secondly, you should be running what fits within your bike’s dimensions. And thirdly, you should consider how your style of riding affects the second thing. Let’s look at those one by one.
What fits you?
The growth in width has been dismissed by many as simple fashion, but while wider bars are certainly fashionable, it’s wrong to think they’re of no benefit. It’s all about stability – it’s simple physics.
Imagine you’re doing a press-up with your hands close together and somebody shoves you. It’s very hard to stop yourself toppling sideways. Now imagine the same scenario with your hands spread naturally… it’s far harder to push you off balance.
This is analogous to what happens on the trails, where tire slips, locked wheels and uneven rocks and roots jostle and pull at your balance. It’s not about wide bars giving you extra leverage over the bike – it’s about the bike having less leverage over you.
Consequently, the right bar for you is the width that spreads your hands into the most natural, stable position. The taller and wider at the shoulder you are, the wider you should go, and vice versa. If it’s hard to keep you elbows unlocked, to stretch the bike down into a corner or to resist collapsing towards the bars under impacts, you’ve gone too wide.
Note that going wider will pull your torso forwards; a shorter stem brings your weight back to its original position, while making steering responses more direct. When upgrading handlebars, it’s best to err towards too wide, as they can always be cut down.
What fits your bike?
Today’s shorter, wider cockpits have been developed in conjunction with longer, slacker-fronted frames that maintain (and often increase) cockpit length. This means that, the older your frame is, the less likely it’s able to usefully accommodate a very short stem/wide bar.
Simplify the press-up example above and you get a triangle: your head at the top, your two hands at the base. Widening that base gives it greater stability. Well, there’s another triangle to imagine here. Viewed from the side, it runs from your head down to your feet, across the front axle to a point ahead, then up the line of your arms to your head.
Again, if the base of that triangle is small (because the bars are too close to the bottom bracket), you have little leverage to resist toppling backwards or – more likely – forwards right over the bars.
This complicates things. It restricts how short you can reasonably go on the stem, which in turn affects your ideal bar width – the steering may become too truck-like if you combine a wide bar with a long stem.
Basically, the shorter and steeper your front triangle, the longer and (slightly) narrower you should keep your stem and handlebars.
What’s right for your style?
The more aggressively you ride, and the more technical your chosen terrain, the more you’ll be rewarded by the stability and direct inputs of a wider bar and shorter stem. The good news is that aero is way less of an aspect in the dirt than on the road thanks to far lower average speeds, so there’s little downside there.
If your riding is more XC and endurance on generally smoother surfaces, your bike is unlikely to have room in the front triangle to work with the extreme end of things. It’s also unlikely to have it your frame is a few years old.
So, as with so many things about bicycles, it’s about finding the best compromise – get as close to the perfect bar width for your shoulders as you can, within the confines of the minimum stem length your bike take before it gets too short.
FSA have everything from its wide, trail-tough Afterburner range to superlight XC and exotic carbon you need to truly make your cockpit the best it can be.