One ring to rule them all
Do we really need two chainrings on our road bikes? Cyclist investigates the pros and cons of the 1x set-up
In the early days of the Tour de France, riders not only had to contend with 400km-plus stages, but they had to do it with just two gears. Not only that, to move between them, they had to get off the bike, release wing nuts on the rear wheel, flip it around and replace the chain on the sprocket before remounting.
These days we expect 22 gears as standard, but do we need quite so many? It might seem obvious that having more gears is better, but there is an argument to be made for losing gears. Specifically, the switch to a single front chainring, known as 1x (‘one-by’), means you can do away with messy cabling, mounts and a bulky derailleur.
‘For me as an engineer, the front derailleur is rather offensive,’ says Gerard Vroomen, co-founder of Cervélo and current owner of Open Cycles. ‘The rear derailleur is a beautiful piece of machinery. The front derailleur consists of two plates that push against the chain until it falls off.’
It’s not just a question of aesthetics. ‘Losing the front shifter makes the bike more aero and lighter,’ Vroomen says. ‘It also requires fewer parts, means no chain drops, and makes shifting easier to understand – that’s important for first-time cyclists.’
The 1x problem
So what’s to stop a rider from converting a normal groupset into a 1x by simply removing the small chainring? ‘Nothing really,’ says Josh Riddle, Campagnolo’s global press manager and a keen crit racer. ‘The only issue is that you don’t have the most efficient chainline when using the larger sprockets in the rear.’
Actually, that’s not the only issue. Others point out that there’s a good chance the chain will repeatedly bounce off the chainring without something other than the derailleur to keep it in place.
‘The front derailleur is a good chain guide, but it isn’t fool-proof,’ says JP Mccarthy, Sram’s road product manager. That didn’t stop time-trial specialist Tony Martin from taking on this year’s Tour de France’s opening TT using a single 58-tooth chainring and a Sram etap rear derailleur. He completed the stage without chain issues, but then he was riding on a very smooth course and has an impeccable pedalling style.
As Tim Gerrits, road product manager at Shimano, says, ‘It depends greatly on the state of your roads. If you’re riding on pristine tarmac every day the chance of dropping a chain is minimal, but how many of us are that lucky?’
Mccarthy is in agreement: ‘Even on smoother roads, narrow tyres transmit more of the road to the drivetrain. Even a paint stripe will challenge the wrong set-up if the chain is long enough to accommodate a 32-tooth cog but you’re riding on an 11- or 12-tooth sprocket.’
To combat this problem, the likes of Sram and Shimano have developed specific 1x groupsets that include a clutch mechanism for the rear derailleur to keep the chain under tension – making chain drops near impossible.
‘In addition, the chainring includes Direct Chain Engagement, where teeth are shaped in opposing ways to hold the chain to the chainring more securely,’ says Gerrits. Shimano’s system is similar to Sram’s X-sync, where teeth are shaped for improved chain retention.
Despite this technology being available, there are still few 1x set-ups designed for road bikes. Shimano’s 1x systems are MTB products, and it’s only Sram that offers a possible road solution with Sram Force Rival 1 and Apex 1.
It seems a fear of losing the full range of our gears is holding manufacturers back from encouraging the use of 1x on road bikes, but that sacrifice may be more a matter of perception than reality.
Finding the gear
While there are fewer gears on offer with a 1x groupset, one of the strange realities of a single chainring set-up is that it doesn’t greatly, if at all, limit gearing range.
‘If you combine our 9-32 cassette with a 36t chainring, it gives you the same range as 48/34 using a 1230 cassette,’ says Vroomen. That’s the same range as a sub-compact double chainset, but it beats the more
conventional set-ups in terms of range too. ‘With a 40t ring it’s equivalent to 50/36 by 11-29, and with a 44t ring it’s equivalent to 54/39 by 11-28.’
While the range may not be a serious issue for 1x, there are more justifiable concerns that the jumps between gear ratios will be significantly bigger than with a standard double-ring set-up.
‘With 1x there are large gaps in metric development between one sprocket and the next,’ says Riddle. ‘While this is fine for cyclocross, which tends to find riders looking to power up ascents, it might not be best suited for road racing. To maintain proper cadence and wattage on a long and varied climb, you need a perfect arsenal of gearing.’
That’s true, although it’s important to note that the number of separate gears is not enormously different to a conventional double chainset. While we may think we have 22 gears with traditional systems, in reality we have use of far fewer. Partly that’s down to chainlines – we shouldn’t use the smallest sprocket with the small chainring or the largest sprocket with the largest chainring – but also because many gears overlap. Here’s where we get a little technical.
Taking for example a 52/36 midcompact with a cassette ranging from 11-28, four gear combinations are within a single gear inch of one another. That means in a full rotation of the pedals, there would be only a single inch of forward movement between them.
When considering gear habits, the gains shrink further. Riders will rarely shift from the upper half of the cassette on the large chainring to the lower half of the cassette on the small chainring to find a perfect gear ratio. Then there are those riders who effectively deny themselves the advantages of a double chainset through a fixation for the big ring and hard gears.
‘Let’s talk about triathlon,’ says Mccarthy. ‘Have you ever seen a triathlete going up a hill? I was at one Ironman a couple of years ago – these guys were pedalling up a minor rise literally in their 53x11.’
Making the switch
For many, then, 1x offers big gains with few sacrifices. So why aren’t we seeing it more? That’s because, as with many things, change starts at the top. For the most part, pro cyclists won’t be using 1x in the near future (although we may see the Aqua Blue team riding 1x 3T Strada bikes next year) as the near-negligible increase in gaps between gears can become quite a big issue on long, fast days in the Grand Tours.
‘I like to think of it as speed differential between user groups,’ says Mccarthy. ‘If you look at the Worldtour groups, they’re fast. When you’re approaching a stage finish in the Tour de France you may be riding at 75kmh but still looking to push up a gear, so you have a precise high gear requirement. Yet on the same stage the same rider could also have a low gear requirement to hit that cadence and power sweetspot going up a long Alpine climb.’
So pros need all 22 of the gears on offer, but for the rest of us perhaps our desire for front shifting is indeed simply an illusion. If so, it’s only going to become more of one when a future of 12 or 13-speed cassettes unveils itself ahead of us.
As Vroomen puts it, ‘I tell people, if currently 1x11 doesn’t do everything you want, don’t focus on changing the “1” at the front; soon they will be changing the “11” at the back.’
‘With 1x there are large gaps between one sprocket and the next. To maintain proper cadence and wattage on a long and varied climb, you need a perfect arsenal of gearing’
The 1x chainring appears to offer big benefits with few sacrifices, but the fact that pro riders won’t be using it very often means manufacturers are hesitant to put it out there
‘The rear derailleur is a beautiful piece of machinery,’ says Cervélo co-founder Gerard Vroomen, who is far less keen on the aesthetic of the front. But appearance isn’t the only reason for doing away with it – a 1x set-up is lighter, more aerodynamic and there are fewer parts to go wrong