It seems counterintuitive. Winter is hard on bikes: rain, salt, grit, roads that tear through components. You would expect bikes to fall apart in February.
But the data from our workshop tells a different story.
The months when bikes most commonly fail catastrophically are not January and February. They are May and June.
Here is why.
The Compounding Problem
Winter does damage slowly. Cold temperatures, road salt, grit: they work together to wear components at an accelerated rate. Chains stretch. Brake pads thin. Cable housings seize. Bearings accumulate moisture.
The rider does not notice. It is cold. They are riding less. The bike is stored more. And when they do ride, they are not pushing it hard.
Then spring comes.
Suddenly the rides get longer. The terrain gets hillier. The pace increases. The bike goes from being a commuting tool to being a fitness machine.
And something that was already borderline gives up.
The chain that has been at 0.8% stretch since February hits 1.2% after three consecutive weekend rides. The cassette that has been slightly worn since March starts skipping. The brake pads that were at 2mm in March are at 1mm after four long rides.
The bike was always going to fail. Spring just revealed it.
The Summer Compound
May compounds the problem. Longer days mean longer rides. School holidays mean family rides. The weather is better, so more people are riding: including people who have not ridden in months.
The average bike in London has been ridden harder in the last six weeks than in the previous six months. Components that were barely hanging on are now genuinely failing.
And June makes it worse. Heat is the enemy of bicycle components. Hydraulic fluid expands. Tyres lose pressure faster. Cables stretch in heat. Metal fatigues.
A bike that has been maintained for winter conditions is not necessarily equipped for summer conditions. The maintenance requirements are different.
What Actually Breaks
Chains are the most common failure. A chain at 1% stretch during a long summer ride, under load, in heat: that is when it snaps or throws. By the time May arrives, most chains that were not replaced in spring are already past their serviceable limit.
Brake cables seize in moisture over winter, then stretch and fray in summer heat. The rider does not notice the gradual decline until the brake fails to return properly or the cable snaps entirely.
Brake pads worn through winter are further worn in spring. The contamination from winter roads: salt, grit, oil from the chain: works into the pad material. Even new pads fitted in March can be compromised by contaminated rotors.
Gear indexing goes out as cables stretch in heat. What indexed perfectly in April shifts badly in May because the cable housing has expanded with temperature. This is especially common in May-June when temperatures swing dramatically between cool mornings and hot afternoons.
Tyre sidewalls crack from UV exposure accumulated since summer last year. The damage is invisible through spring: the tyre looks fine: but the structural integrity is compromised. Long rides in June heat are when UV-cracked sidewalls fail.
The Seasonal Pattern
If you look at our workshop calendar, there is a clear pattern:
- February-March: Services. People want their bikes ready for spring.
- April: Quiet. The bikes that were going to fail already did.
- May-June: Crisis. The bikes that survived winter are now failing under spring/summer load.
- July: Steady. The bikes that made it through May are running OK. The ones that did not are off the road.
The riders who brought their bikes in for a service in February are fine. The riders who did not: they are the ones calling us in May with chains that have snapped, derailleurs that have broken, brakes that will not work.
The Cost Of Waiting
A full service in May costs between £120 and £300 depending on the package. A major repair after a component failure costs £200-500 in parts alone, plus the bike being off the road for days or weeks.
The chain that could have been replaced for £45 in April costs £200 to replace along with the cassette it destroyed in May.
The brake cable that could have been replaced for £15 in a service in April snaps on a descent in June, leaving the rider without brakes.
The £150 service that seemed expensive in April is £500 of repairs and a ruined holiday in June.
What A Late Spring Service Should Include
If you are riding through May and June, your service needs to account for seasonal stress, not just winter damage.
- Chain inspection and measurement: not just cleaning. Measure stretch with a ruler. If it is past 0.5%, replace it before a long ride. A new chain now costs £45. A new chain plus cassette later costs £200.
- Tyre inspection: check sidewalls for UV cracking, not just tread depth. The centre tread can look fine while the sidewall is structurally compromised. UV damage is not visible as wear: it is visible as fine cracking.
- Brake system flush: DOT fluid absorbs moisture over time. If your brakes felt spongy over winter, they will be worse in summer heat. A bleed now prevents brake fade on a long descent later.
- Gear cable replacement: regardless of whether they seem broken. Summer heat makes cables expand. New cables installed in May will handle the summer better than cables that have been sitting in moisture since October.
- Bearing inspection: headset, hubs, bottom bracket. Cold weather causes condensation inside bearings. By May, that moisture has been working on the races. An inspection now catches what becomes a breakdown later.
The Bottom Line
Your bike made it through winter. That does not mean it is ready for summer.
May and June are the most dangerous months for bicycle mechanical failures: not because of what happens in those months, but because of what has been building since October.
If you have not had a service since October, book one now. Before your big summer ride. Before your holiday. Before the failure that ruins the plan.
A service booked in May costs what a service costs. A breakdown in June costs significantly more.