Changing the stem length of a mountain bike changes the center of gravity on the bike and its ride characteristics. A short stem will give you more confidence and sensitivity when descending. The long stem places your body weight forward, allows a better climbing position for more pedaling power, and helps prevent the front wheel from lifting during steep climbs.
Over the years, as mountain bike geometry and design have evolved, many types of mountain bikes have seen a trend towards shorter and shorter stems.
It is especially evident with trail bikes – an increasingly capable and growing segment of mountain biking.
Bikes are longer and looser, with wider bars and shorter stems – but why is that, and does a longer stem still have a place these days?
What is a strain?
First, we need to understand what a stem is. A modern stem looks like the image below. It is the bridge between the top of the fork and the handlebars. It has two clamps, both on the back, and typically four clamp screws on the front. These come in many different shapes and sizes, and some are even unique to specific bikes and can only be replaced with other stems made by the manufacturer.
Short stem vs. Long stem:
Walk into any bike shop, and you’ll find that short stems are now commonplace – with 50mm stems and often below the standard offering on a trail bike.
In some context, in years past, there would have been XC bikes with 80-120mm stems and downhill bikes with diameters of 40mm and under.
These days trail/enduro bikes have become super capable; they can climb well and still go down some pretty rugged trails quickly.
One of the reasons they have evolved into such capable machines is the combination of wider bars and shorter stems.
It provides great stability and control when descending, thanks to more torque when turning the bars and a more direct response from the shorter stem.
It is common to find trail bikes ridden with 800mm wide bars and a 30-40mm stem due to these favorable characteristics regarding aggressive trail riding, descents, and elements such as jumps and drops.
Jump back on an older bike with narrow handlebars and a long stem; it feels incredibly jerky and a lot less confident on the descents.
Some XC riders have backed away from some stem lengths and tried running wider bars. However, most dedicated XC riders are still running noticeably longer stems than most casual mountain bikers who are more into the local trail network or bike park.
The main reason is that shifting the weight on the bike slightly forward ensures that the front wheel stays on the trail when climbing and the rider sits in the perfect position to maximize their pedaling power.
Of course, this makes a big difference if you’re primarily interested in riding long trail runs and grueling climbs.
However, for most mountain bikers, myself included, climbing is very often just a necessary evil to get to the part I enjoy the most, the descent!
So for me and many other mountain bikers, I much prefer to hit the trails with 800mm bars and a 50mm stem and deal with an imperfect climbing position in favor of the epic fun I know I’ll have once I reach the top of the trail.
50mm is no longer considered a short stem. Maybe I should try the 35mm one for the next upgrade, just to see how it feels on the bike.
Does it only affect climb vs. descent?
Not at all.
But it’s certainly one of the most noticeable bike-handling changes since the stem length change.
The shorter stem gives the bike a more responsive feel on the trail and is suitable for aggressive riding.
When jumping your bike or hitting drops, a shorter stem puts you in a better position to confidently hit those features (which often have painful consequences if we don’t ride them well).
Should I replace the stem with a shorter one?
If you prefer to drop and hit jumps and run with a stem longer than 50mm, I’d recommend trying something 50mm or less, you’ll love it.
You’ve probably noticed by now that I prefer shorter stems – and that’s true.
But I’m also not one to blindly follow trends and buy the latest bikes every season.
Many riders find a 50mm stem too long and would have switched to a 35 or 40mm stem years ago.
But then I’ve been riding my Bronson since late 2013, shortly after it was first released.
Since then, there have been many years of bike technology improvements and many marketing cycles.
I just don’t think we need to keep buying every new thing that comes out (and yes, the bike industry is fantastic at changing the “standards” regularly).
At the end of the day, if we have a capable mountain bike and a love for the sport – that’s enough to get us out there and have an amazing bike experience.
Should I have a shorter stem?
It is a question I get asked a lot. As a bike fitter, many people come to me and ask me what the approximate length of the stem should be, but it depends on a lot more than just the bike and your height. It is unique to the user.
They ask this because, in recent years, we have seen smaller and smaller stems on bikes, and there are many reasons for this; for example, the bikes are designed differently, people now value comfort over speed, and it just looks a lot cooler.
There are huge benefits to going with a shorter stem, and usually, many bikes now naturally come with shorter stems as they are suitable for more riders. Shorter stems are fantastic for people who do technical riding or generally want a little extra comfort.
As a long-distance rider, I greatly prefer a shorter stem on my bikes. It all depends on personal preference and how you feel while driving.