Article by Simon Davis – Sport & Spinal Physiotherapy
There is lots of information out there on what seat height you need, knee angle and cleat position. But what about your upper body? Where should it be on a bike.
This article is going to go through correct torso and arm position for cyclists as well as some of the mistakes I commonly see when doing bike fits or out on the trails watching other riders.
We need to look at 3 different types of riders – Mountain bikers, road cyclists and specifically time trial position. The position you adopt comes down to comfort, speed, endurance, and safety/bike handling ability.
So here are some basic concepts around body position on a bike.
Speed vs Power
Everyone wants more power, right? With more and more riders using some sort of watt measuring device knowing your power output is becoming more common. But does more power equal more speed? Not necessarily. At 30km/h on a flat road approximately 90% of your forward power is put into overcoming wind resistance. Consequently, it is faster to be in a more aerodynamic position, even if it means sacrificing the number of watts you can put out. Essentially a lower torso position is more aerodynamic but less powerful due to your glutes and hamstrings not being in a weaker position. Which leads me to my next point…
Muscle length tension relationship
Due to the way muscles work, they generate force best in a “mid-range” position. They don’t work as strongly in either a very stretched out position or very cramped position. As a result, there is such a thing as too low on a bike.
If your torso starts to get below 20 degrees to the horizontal then your glutes and hamstrings will be in such a stretch that your power with be drastically reduced, causing your speed to drop off. If you have poor flexibility through these muscles that may even be up around 25 or 30 degrees to the horizontal. Which brings me to my next point.
Just because it is faster to be at 20 degrees to the horizontal, it doesn’t mean that you should be there. I can last in that position for about 20 minutes before my back is hating me. So often we compromise with a position that is less aerodynamics oriented and more comfort driven.
On a mountain bike aerodynamics aren’t really an issue most of the time. Torso position is more important when it comes to power production and bike control.
“Best” upper body position for your bike
- Moderate lean forward with a relatively flat back whilst on the hoods (I often use the cue for people “sternum up and forwards”.
- Relaxed elbows at 15-20 degree bend. If you lock your elbows out the tendency is to raise the shoulders and round out through the upper back causing neck pain. It also difficult to handle the bike in some situations.
- Similar concepts on the drops – low as is comfortable without going below 20 degrees to the horizontal with your torso.
Tri or time trial bike
- Similar torso position to being on the drops of a road bike.
- Arms tucked in on the aerobars with a 8 degree raise angle from the elbow to the hand – if you have your aerobars dead flat you have to fight against sliding forwards all the time. It also feels a lot more comfortable from a handling perspective to have that slight rise in the aerobars, especially if the road surface is a little bumpy.
Mountain bikes get a little tricky so we’ll go with climbing to begin with. As noted above, aerodynamics is less important than on a road bike. However, on a particularly steep climb you still need enough weight over the front wheel to keep it on the dirt.
- Moderate lean forward – usually about 45 degrees at the torso, elbows relaxed and slightly bent. As a climb gets steeper you may need to bend at the elbows more to keep the front wheel grounded.
- Locking the elbows out often feels easy but similar to on the road bike can cause neck pain due to the shoulders hunching. It is also a nightmare from a bike handling perspective.
When descending on a mountain bike with any technical features, again often aerodynamics isn’t the main issue. It is far more about the ability to handle things like corners, drops, jumps or abrupt changes to momentum such as breaking ruts or rock gardens.
- If you’re not out of the saddle you should be! Dropper or not, the rule on a mountain bike is if you aren’t pedalling, you shouldn’t be sitting. This allows you to move the bike underneath you far more effectively and transfer your centre of mass forwards, backwards or side to side without upsetting the bike. Also, if you hit something that slows your momentum or changes your bike behaviour abruptly and unexpectedly, you do not want your centre of mass to be heavily affected or you may end up no longer on the bike. I refer to this as being able to disassociate your bike from your body.
- Starting position is similar to pedalling position, just standing taller through the hips away from the saddle.
- Elbows slightly bent, torso in a sustainable position. Too much elbow bend at this stage is exhausting – remember about the length tension relationship of muscles. Triceps don’t want to work for too long with the elbows fully bent (imagine holding a push up in the lowest position versus just off fully straight). Straight elbows are dangerous as you are at the mercy of the bike if it hits something.
- Ideally you should still be in the centre of the bike with your weight through the pedals. Too far forward can be tiring on the arms. More commonly riders sit too far back which feels safe, but then there is no way of getting further back when a dynamic movement is required for an obstacle. It’s also exhausting on your hands as you hang constantly pulling on the handlebars.
- The next movement and body position will depend on the obstacle or technical manoeuvre that you are trying to do. From this strong starting position you have the potential to move your weight back if required to throw the bike forwards through a rock garden, bend the elbows and get lower to transition into a bunny hop/manual or go off a drop, or bend one side to lean your centre of mass into a corner.
- Don’t forget to return back to the sustainable athletic starting position. I often see riders get lower with each obstacle rather than reset in between. This is tiring on the low back and arms but also limits your ability to move the bike around underneath you as required.
If it is horribly difficult for you to adopt or sustain any of these positions it is probably time for a bike fit. Being on your bike should be like sitting at a desk with a computer set up to your height – it should promote good posture rather than you fight to maintain good posture. There is also the potential that your body does not have the flexibility or strength to maintain these positions. Consequently, getting a bike fit with a Physiotherapist is often helpful as they can assess these aspects of your body.