Many mountain bikers spend hours trying to find the ideal tyre compound, perfecting their suspension settings or choosing the right handlebars. When it comes to grips, however, the decision is often made in passing: you like the colour, the tread looks grippy, so you buy them.
This is a mistake that becomes apparent, if not before, then certainly on long descents. After all, grip strength is one of the most important factors for comfort, control and safety on a mountain bike. If the diameter is too small or too large, you risk numb fingers, sore palms or forearms that tire prematurely.
But which grip thickness suits which hand size? Is there even such a thing as an ideal size? And why do some enduro pros deliberately use thicker grips than XC racers? We explain how to find the perfect grip thickness for your mountain bike.
Why the thickness of the handle is so important
The handlebar forms the direct link between the rider and the bike. It transmits steering inputs, absorbs shocks and controls braking manoeuvres.
The problem is that our hands are constantly under strain whilst riding. On rough trails, there’s a constant cycle of gripping, stabilising and braking. Even small differences in grip diameter can therefore have a major impact on the riding experience.
The thickness of the handle affects:
- Force required for grasping
- Pressure distribution in the hand
- Control over the bike
- Vibration damping
- Ergonomics of finger positioning
- Fatigue in the hands and forearms
In other words: the wrong size can turn even the best handle into a poor choice.
What happens if the handles are too thin?
At first glance, slim grips often look sporty and streamlined. In fact, they are particularly popular with many XC and marathon riders. However, they also have their drawbacks: if the grip is too small for your hand, you have to clench your hand tighter. Your fingers grip the handlebars more tightly and the muscles are under constant strain.
Typical consequences:
- Greater pressure on the palm of the hand
- Faster onset of finger fatigue
- More strain on the forearms
- Higher risk of arm pump
- Numbness on long descents
Riders with large hands, in particular, often report that they unconsciously have to grip the handlebars much more tightly if the grips are too thin.
What happens if the handles are too thick?
The other extreme is also problematic. An oversized grip can prevent the fingers from gripping the handlebars securely. The hand loses its fine motor skills and sense of the road surface.
Typical consequences:
- Less direct contact with the bike
- Reduced steering feel
- Greater effort required when braking
- Less confidence when tackling technical sections
Riders with smaller hands, in particular, often find it difficult to control thick grips properly. The bike then often feels less precise, even though the grips are actually meant to offer greater comfort.
The rule of thumb: it all comes down to hand size
Although there is no universal formula, hand size is a good starting point. To measure this, you usually measure the distance between the tip of the middle finger and the crease of the thumb. A rough guide to sizes can be given as follows:
Small hands – up to approx. 13 cm in length
Typically suitable for:
- Thinner handles
- Diameter between 28 and 30 millimetres
Advantages:
- Improved grip
- Greater control
- Easier access to the brake levers
Of particular interest to:
- Women
- Young people
- Riders with short fingers
Medium-sized hands – up to approx. 15 cm in length
Typically suitable for:
- Handles with a diameter of 30 to 32 millimetres
Advantages:
- A good balance of control and comfort
- Suitable for universal use
- The widest range of models on the market
This category covers the classic all-round range.
Large hands – from approx. 15 cm in length and upwards
Typically suitable for:
- Handles from 32 millimetres
- Comfort models with a width of 34 millimetres or more
Advantages:
- Fewer pressure points
- A relaxed finger position
- Greater comfort on long descents
Enduro and e-MTB riders, in particular, often benefit from larger diameters.
Grip thickness and arm pump – the often-overlooked link
Hardly any other topic is discussed more frequently in the world of gravity sports than arm pump. This painful swelling of the forearm muscles is caused by prolonged strain and restricted blood flow. Grip strength plays a bigger role in this than many people realise.
If the handle is too thin:
- The fingers need to grip more firmly.
- The muscles are constantly working.
- Your forearms get tired more quickly.
A slightly larger grip can help your hand to relax and reduce the amount of force required. That is why many riders start by changing their grips before investing in expensive suspension or brake upgrades.
Finding the perfect grip strength – a simple practical test
The simplest method is surprisingly straightforward. Hold an assembled handlebar in the normal riding position. Bear the following points in mind:
- Your fingertips should not touch the palm of your hand.
- Your hand should be able to grip the handle loosely.
- The handle must not give the impression of feeling ‘loose’ in the hand.
- The brake levers must remain within easy reach.
- The muscles in your hand should remain relaxed even after a few minutes.
If you experience a feeling of pressure or tightness whilst standing still, the diameter is usually not quite right.
These signs suggest it’s time to change the grip
Many cyclists get used to discomfort and regard it as normal. Yet the hands often send clear warning signals. A different grip diameter may be advisable if:
- My fingers often go numb
- My forearms get tired quickly
- The palms of my hands hurt
- My hands are cramping up
- The handlebars are held too tightly all the time
- Control tends to slip on long descents
In many cases, the problem can be significantly improved simply by changing the handle, at a cost of just a few euros.
Comfort or control – do you have to choose?
The good news is that modern MTB grips often achieve both. Many manufacturers combine larger diameters for greater comfort with soft lamellar zones for better shock absorption. Some grips on the market feature a thinner plastic core in high-stress areas, or do away with it altogether in certain places. This allows for the use of more material to provide better shock absorption. Finally, different rubber compounds can also be combined within a single grip to maximise both grip and shock absorption.
Conclusion: The ideal grip strength is as individual as your hand
Choosing the right handlebar diameter is one of the most underestimated aspects of mountain biking. Yet hardly any other component offers such a significant impact on comfort, control and riding enjoyment for so little money.
If you frequently struggle with tired forearms, numb fingers or aching hands, you shouldn’t immediately blame the chassis, handlebars or brakes. Often, the cause is simply that you’re gripping the handlebars too tightly.
My tip: Under no circumstances should you choose handles based solely on colour or appearance. The size of your hand, the intended use and a quick practical test will help you choose the right model.
Stefan Frey
Editor