Last week, reports revealed the UCI will trial a ban on big gears in road cycling this summer in a bid to reduce speeds and improve safety.
Following speculation that the trial ban would disproportionately affect SRAM-sponsored teams, the UCI sought to “provide further clarification” with a press release uploaded to its website last Friday.
We also now have the original memorandum sent out as part of a newsletter from the UCI, which details how the trial will be implemented.
A detailed reading of the trial appears to show the UCI is overlooking at least one crucial aspect in bicycle gearing, and hugely underestimating the potential impact of another.
If the trial proceeds as described and is adopted as a permanent technical regulation for 2026 onwards, then short cranks and big road bike tyres will almost certainly become ubiquitous on WorldTour race bikes. Here’s why…
- UCI to trial ban on huge gears – and SRAM riders now have a big problem
- The UCI has just announced huge changes to its tech regulations – and some industry insiders are furious
Tyre size affects roll-out
As larger tyres increase a wheel’s effective diameter, tyre size also affects gear development meters.
Gear development meters – also known colloquially as ‘roll-out’ – is a measure of how far your bike travels with a complete revolution of the crank.
The larger the diameter of a wheel, the bigger the roll out for a given gear ratio.
According to the UCI’s memorandum on the trial, the trial will test “limiting the maximum gear ratio of the chainring and cassette to a distance covered per pedal revolution of 10.46 meters or an equivalent of 54 x 11 [teeth].”
The problem is that a roll out of 10.46m only applies to a 54x11t gear ratio paired with 28mm-wide tyres.
UCI acknowledges this, saying: “Regarding tyre width, the most commonly used sizes will likely be 25mm and 28mm, with 30mm as the upper limit.
“For testing purposes, the width will not be taken into account, given that the difference in rollout between 25mm and 30mm is approximately 1.5 per cent”.
Instead, the memorandum implies riders will be permitted to have chainrings no larger than 54t an sprockets no larger than 11t – bikes with SRAM cassettes, it notes, “can be mechanically limited before the race by teams’ mechanics” (forcing those riders to get by with only 11 instead of 12 sprockets, for the duration of the test – have your small violins at the ready).
As the three tables included by the UCI from BikeCalc.com show, there’s a tangible difference between the roll out of the three tyre widths noted with a 54x11t gear.
With that gear combination, a bike will roll 10.52m during a single pedal revolution with 30mm tyres – 6cm further than with 28mm tyres, and 16cm further than with 25mm tyres.
All else being equal, riders with wider tyres will therefore ride further – and therefore faster – for a given cadence when using that top gear.
1.5 per cent is a chasm
To imply this is only a small difference is, frankly, mind-boggling – a difference of 1.5 per cent is a chasm when career-defining races are frequently decided by photo finishes.
Leaving aside bunch sprints, the six minutes and seventeen second gap between Tadej Pogačar and second-place finisher Jonas Vingegaard at last year’s Tour de France, for example, represented just a 0.9 per cent difference over three weeks of racing – and was considered one of the most dominant Tour victories of recent memory.
Of course, if every rider were to use 30mm-wide tyres then there would effectively be a level playing field in this respect.
However, the UCI’s dismissal of tyre size as an issue in this debate implies it doesn’t understand what it is attempting to regulate.
If the trial regulation is adopted as a permanent fixture of the technical regulations, it is imperative the UCI conducts proper roll-out tests before every race – simply checking chainring and sprocket sizes is not enough.
Otherwise, riders will effectively be able to game the system by using larger tyres that increase their gear development meters.
And if the UCI is to regulate tyre width in its events – having 30mm as an “upper limit”, for example – then what happens during the cobbled classics, where riders are routinely using tyres larger than that?
As usual, this latest intervention by the UCI leaves us with more questions than answers.
Crank length also affects gearing
Tyre size aside, crank length also affects gearing – and it appears the UCI has completely missed this one (or at least thinks it's of such little importance that it wasn’t worth mentioning).
As Phil Burt, a leading bike fitter and former head of physiotherapy at British Cycling, told BikeRadar, for our article on the best crank length for cycling: “When you change your crank length, you’re effectively just changing your gearing. A longer crank essentially just gives you a slightly easier gear, and vice versa.”
In the context of our article on crank length, Burt’s point was that choosing a shorter crank length wouldn’t make it harder to produce power because you can change gear to an easier gear and simply pedal faster (because shorter cranks have a smaller turning circle).
In a world where chainring and sprocket sizes are limited, choosing a shorter crank would be another way to eke out an advantage.
If you can’t switch to a higher gear, then the only way to ride faster is to increase your cadence – and one way to do this more easily is by using shorter cranks, which travel a shorter distance per pedal revolution.
There’s no free lunch, of course. Because you lose leverage compared to a longer crank, it’s harder to turn that same gear combination with a shorter crank (effectively, your gear ratio has increased).
But if you can do it – and no doubt sprinters will train for ultra-high cadence efforts if this rule comes into permanent effect – then being able to spin the same gear combination as your competitors at a higher cadence will, all else being equal, enable you to ride faster than them.
In contrast to the UCI’s recently announced regulations surrounding minimum handlebar widths, which appear set to penalise shorter, slimmer riders, limiting gear ratios in this fashion could therefore favour shorter riders who are able to better utilise shorter cranks.
Spare a thought for Movistar’s Mathias Norsgaard – the tallest rider in the WorldTour peloton at 2.02m – who might have to somehow adapt to using the tiny 150mm cranks we've seen Jonas Vingegaard testing this season, for example.
Perhaps riders will experiment with even shorter cranks should this rule be made permanent… And then perhaps the UCI will respond with a minimum crank length for 2027, too.
