Module 1 of 3 · 35 minutes
The M check: find the fault before it finds you
By the end of this module you will be able to
- Carry out a full M check on any bicycle in under five minutes
- Identify the faults that make a bike unsafe to ride today
- Tell the difference between wear that can wait and wear that cannot
- Know which jobs are yours and which belong in a shop
Work through it
1 interactive for this module, built on the WAJD Teach engine. Nothing moves until you ask it to, and every one has a written version if you would rather read it.
Amara I have owned bikes for twenty years and I have never once done a systematic check. I just get on and ride.
Nadia Most people do, and most of the time it is fine, because a bicycle is a very forgiving machine right up until the moment it is not. The M check takes five minutes and it exists because the failures that hurt people are boringly predictable.
Amara Why an M?
Nadia Because your hands trace one. Front wheel, up to the bars, down to the pedals, up to the saddle, down to the back wheel. It is a route, not a checklist, which is why it survives contact with a cold morning when you are in a hurry.
Amara Start me at the front wheel. What am I actually doing?
Nadia Spin it and watch the gap at the brake pads. If that gap opens and closes as it goes round, the wheel is buckled. Then grab the tyre at the top and rock it towards you and away. If it knocks, the hub bearings are loose.
Amara And the quick release?
Nadia Check it is properly closed, not spun up finger tight. The lever should need a firm push with the heel of your hand and leave a mark on your palm. A quick release that is merely tight will work loose, and a front wheel leaving a fork at speed is one of the worst things that can happen on a bicycle.
Amara Tyres?
Nadia Look for cuts, embedded flint, and bulges. A bulge in the sidewall means the casing has failed and the only thing holding the pressure is rubber. That is not a wait and see, that is a replace before you ride.
Amara Up to the bars.
Nadia Stand over the front wheel, grip it between your knees, and try to turn the bars. Nothing should move. If the bars turn against the wheel, the stem bolts are loose and you have no steering when you most need it.
Amara Then down to the pedals.
Nadia Rock the crank arms towards and away from the frame. Any knock is a loose crank bolt or bottom bracket. And a loose crank matters more than people think, because riding on one for a week will chew out the crank arm and turn a two minute job into a new chainset.
Amara So what actually stops me riding today?
Nadia Four things. Brakes that will not lock the wheel or a lever that pulls to the bar. A wheel that is not properly secured, or a bulging or split tyre. Bars or stem that move relative to the wheel. And any crack in a frame, fork or handlebar.
Amara Cracks are the one I would be tempted to ignore.
Nadia Do not. Aluminium and carbon do not bend and complain the way steel does. They hold, and then they let go all at once. A cracked fork is not a judgement call and it is not a home repair.
Amara Last thing. How do I know when a job is beyond me?
Nadia There is a proper list, and it is in the written material. But the test that has never let me down is simpler than a list. Would you be happy watching somebody you love ride that bike down a long hill? If you find yourself starting a sentence with it is probably fine, you already know the answer.
The written material
Why an M
The M check is the standard pre ride inspection used by cycle mechanics and instructors, and it is called that because your hands trace an M over the bike. Front wheel up to the bars, down to the pedals, up to the saddle, down to the back wheel. One route, nothing missed.
It takes about five minutes once you know it, and it catches the four things that actually hurt people: brakes that do not stop, a wheel that is not attached properly, a tyre about to fail, and handlebars or a stem that can move under load.
What you are feeling for at each point
At the wheels: spin them and watch the gap at the brake pads to spot a buckle. Squeeze pairs of spokes to find a loose one. Grab the tyre at the top and rock it side to side; movement means the hub bearings are loose. Check the quick release or through axle is properly closed, not just spun up finger tight.
At the tyres: look for cuts, bulges, embedded flint and worn tread. Check the pressure against the number moulded into the sidewall. A bulge in the sidewall is not a wait and see, it is a replace before you ride.
At the bars and stem: stand over the front wheel, grip it between your knees and try to turn the bars. Any movement means the stem bolts are loose. Pull the brake and rock the bike forwards to check the headset for knocking.
At the pedals and cranks: rock the crank arms towards and away from the frame. Movement means a loose bottom bracket or a loose crank bolt, and a loose crank will destroy the crank arm quickly if you ride it.
At the saddle: check it does not twist and is not above the minimum insertion line marked on the seatpost.
The four that stop the ride
Most of what an M check finds can wait until the weekend. Four things cannot, and it is worth committing them to memory.
- Brakes that do not lock the wheel when squeezed firmly, or a lever that pulls to the bar
- A wheel that is not correctly secured, or a bulging, split or badly worn tyre
- Handlebars or a stem that move relative to the wheel when clamped between your knees
- A cracked frame, fork or handlebar, especially at a weld or a bend
Know your limit
This course teaches you to do a great deal yourself. It is equally important to know what to hand over. Anything involving hydraulic brake internals beyond a simple bleed, wheel building and serious buckles, bearing pressing, carbon component torque, and any suspected frame damage belongs with a shop.
The rule that keeps you safe: if you would not be happy for a member of your family to ride down a hill on it, do not finish the job by convincing yourself it is probably fine.
Knowledge check
The knowledge check and your certificate need a free account, so that your progress and results can be saved as evidence.
The learning itself stays free and open. You are reading all of it right now without an account.