He had ridden it in on a certificate with three days left, expecting the usual. The tester came out holding the sheet and the first item on it was the number plate.
Not the brakes, which were fine. Not the tyres, which were nearly new. The plate, which he had bought at a bike show four years earlier because it looked better than the standard one, and which had been quietly illegal on every one of the four MOTs it had passed since. A different tester, a different morning, and a bike that could not legally leave the forecourt over a piece of acrylic costing under twenty pounds.
That is a fairly typical bike MOT failure. Not a catastrophe, not expensive, and entirely avoidable by anyone who knew what to look at.
What bikes fail on
The items differ from cars, and the differences follow from bikes being lighter, more exposed and simpler.
Lighting and signalling. Consistently among the most common. Bulbs, dead brake light switches, number plate lights, indicators flashing at the wrong rate after an LED conversion.
Brakes. Pad thickness, disc wear, spongy levers, and corroded or perished hoses on machines that have lived outdoors.
Tyres. Tread below the limit, perishing on bikes that do low mileage, sidewall damage, and occasionally the wrong tyre fitted.
Steering and suspension. Notchy head bearings and weeping fork seals. Both are ordinary wear items and both are frequently ignored until test day.
The registration plate. Wrong dimensions, wrong font, wrong spacing, single-line plates on bikes that need two lines, and tinted covers. Very common, and unlike most of this list it costs almost nothing to fix.
Drive chain. Excessive slack, tight spots, hooked sprockets, missing chain guard.
Corrosion. Anything stored outside collects it. Brake lines, exhaust mountings, subframes and fasteners.
Exhaust. Blowing joints, insecure mountings, and noise on machines wearing a can with the baffle taken out.
Frame number illegible. Less common, but a straightforward failure and one people are surprised by.
Why bikes fail on things cars do not
Everything is exposed. Brake lines, fasteners, bearings and electrical connectors sit in the weather with nothing over them. A car's equivalent components live inside a body.
Low mileage causes its own problems. A bike doing 1,500 miles a year perishes tyres, seizes cables, corrodes discs and degrades brake fluid without ever wearing anything out.
Modification is normal. Most bikes on the road have been changed in some way, and aftermarket cans, plates, indicators and levers are all things a tester will look at against a standard the owner may never have read.
Storage over winter. Six months standing still is hard on a machine. Fluids settle, seals dry, discs corrode, batteries die, tyres flat-spot.
What you can legally do with a failed bike
This is the part people get wrong, and it matters because the alternative is riding uninsured as well as untested.
If the certificate has expired, you may ride the bike to a pre-booked MOT appointment or to a garage for repairs. Not home. Not to a friend's lock-up to work on it at the weekend, unless there is a booked repair at the other end.
If the certificate is still valid, a failure does not automatically ground you, but riding a bike with a dangerous defect is an offence regardless of what any certificate says.
Dangerous defects are a separate matter. Where a bike is failed with a dangerous defect, riding it away is not something to attempt. Have it repaired where it stands or move it on a van or trailer.
Insurance follows all of this. Cover can be affected by riding without a valid certificate, which turns a plate failure into a considerably larger problem than it needs to be.
This page is general information about running a bike, not legal advice.
Retests
Same centre, within ten working days. Usually free or reduced, depending on what was repaired and whether the bike left the premises.
Left the premises, or longer than ten working days. Expect to pay again, potentially in full.
Partial retests cover a defined list of items. Ask at the desk before you leave, because whether your particular failure qualifies determines whether it is worth taking the bike away at all.
The sensible move is always the same: ask what the retest position is before you ride off, not after.
Buying a bike that has failed
A failure sheet on a bike for sale is not automatically a reason to walk away, and it is sometimes an opportunity.
Read what failed. Bulbs, a plate and a chain are an afternoon and under a hundred pounds. Head bearings, forks and a pair of discs are a different conversation.
Price it as it stands. A bike with a live failure is worth what a bike with a live failure is worth. The seller's optimism about how easy the fix is does not change that.
Look at the pattern. A bike that fails on the same category three years running has an owner who is not maintaining it. Check the write-off record too, because a badly repaired write-off often announces itself through alignment, suspension and brake failures.
Remember the transport problem. If the certificate has expired, you cannot simply ride your new bike home. Factor a van into the price.
FAQs
Can I ride my bike home after it fails?
Only if the certificate is still valid and the bike has no dangerous defect. If the certificate has expired, you may ride to a pre-booked repair or test appointment and nowhere else.
How long do I have to fix it?
There is no fixed period, but the retest concession at the same centre generally runs to ten working days. Beyond that, expect a full fee.
Does a failure show up on the bike's record?
Yes. Failures and their items stay on the MOT history permanently, which is why a buyer can see them years later.
Will one failure affect what the bike is worth?
A single ordinary failure, very little. A pattern of them across several years affects both value and how much a buyer trusts the rest of the bike.