Riding puts three different loads through the hands at once:
- a sustained grip on the bars,
- continuous vibration from the engine and road, and
- the wrist held in extension while carrying some of your upper body weight
Arm pump is the famous consequence – it’s not the only one, and it is not the most serious.
Arm pump
Forearms swell, harden and stop working, usually at a predictable point in a ride or a race. Grip and brake feel go, which is a safety problem before it is a comfort one.
- The commonest cause is gripping far harder than the bike needs, often from tension rather than technique. Notice your grip on a straight: most riders are holding on as if braking
- Setup matters. Lever position and reach, bar height and rotation all change how much your hands carry. A lever angled wrong makes you bend the wrist to reach it on every brake
- Grip the tank with your knees, so the legs carry your body and the hands only steer
- Softer grips and thicker grips reduce both vibration and grip force
If the forearm becomes hard, painful and numb during riding and takes a long time to settle afterwards, that is worth assessing properly rather than training around.
The full picture is in exertional forearm pain, where the timing is the diagnosis.
You are not holding on. The bike does not fall over because you loosened your grip on the straight.
The nerve problems
- Numbness in the ring and little fingers: pressure through the heel of the palm on the bars compresses the ulnar nerve at the wrist — Guyon’s canal syndrome. Cyclists get the same thing, which is why it is sometimes called handlebar palsy. Rotating the bars, thicker grips and taking weight off the hands all help
- Numbness in the thumb, index and middle fingers: carpal tunnel syndrome, from vibration plus sustained extension
- Numbness in ring and little fingers plus the back of the hand: the problem is at the elbow instead — cubital tunnel
- Fingers going white in the cold after years of riding: vibration white finger, which is cumulative and does not fully reverse. Heated grips are a genuine intervention here, not a luxury
Throttle and clutch hands
Long rides on a fixed throttle position load the wrist in one posture for hours. A throttle lock or cruise control on a touring bike is a hand intervention.
Heavy clutch springs, repeated in traffic, drive forearm and elbow tendon pain — see golfer’s elbow and tennis elbow, both of which turn up in riders who commute in cities.
After a crash
Riders go down with hands out. The two that get missed:
- Tenderness in the hollow at the base of the thumb, even with a normal X-ray: scaphoid fracture until proven otherwise
- A finger that crosses its neighbor when you make a loose fist: a rotated finger fracture, which needs correcting regardless of how the X-ray reads
Gloves hide swelling and adrenaline hides pain. Check both hands properly once you are off the bike and calm, not at the roadside.
When to get it looked at
- Numbness that persists after you stop riding
- Grip or brake feel that fails partway through every ride
- Fingers blanching in the cold
- Forearm pain at rest rather than only under load
- Any hand pain still significant a week after a crash
Numb hands on a bike are not part of riding. They are a nerve telling you where your weight is going.
Every article on this site is written using the Closing Window Method: name the window your condition runs on, find where you are in it, and act while it’s still open.