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Are 1x groupsets the future for road cycling?

Peter Stuart
30 Sep 2019

With 1x groupsets appearing across road disciplines at the World Championships last week, are the front derailleur's days numbered?

The UCI Road World Championships in Harrogate will go down as one of the most historic instalments of the race - with riders racing in almost aquatic racing conditions.

Amongst the epic racing, though, we were particularly excited to see one bike amid the fleets of shining carbon race machines.

Bauke Mollema's Trek Madone was, at a glance, nothing new. It sported the stunning bowling ball-esque red finish that Trek showcased at the Tour de France, and the bike's iconic chunky tube shapes and IsoSpeed decoupler suspension system. 

Looking closer, though, it drastically deviated from the normal spec of the Madone in one way – it had no front derailleur.

Mollema was riding a Sram Red AXS groupset 52 front chainring with a 10-33 rear cassette.

While many, including several pros we spoke to, derided the lack of range offered by a single chainring, it's worth nothing that his range was greater in this setup than with a normal double chainset (53-39) using a tight 11-25 rear cassette.

Mollema did not finish the Men's Elite road race, along with more than a hundred other competitors who were defeated by the extreme weather conditions. However, more successful riders also sided for 1x groupsets.

These include Alex Dowsett, who finished 5th in the Elite Individual Time Trial, who also rode a single 52-tooth chainring on a Sram Red AXS groupset.

For time trials, such deviations are not uncommon as riders traditionally need less range for all-out flat TT stages. However the use of 1x systems for time trial stages has been more common than in previous years.

The World Championships also saw a road race medallist aboard a 1x equipped bike. Bronze-medallist in the Junior Men's Road Race Magnus Sheffield rode a 1x setup on a 3T Strada bike.

The question is, then, if a 1x groupset is good enough to race the world's best on the road, do we really need a front derailleur for normal road cycling? Let's go back to the basics of why we have two chainrings in the first place. 

Ditching the front derailleur

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, previously 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.

Previously we've seen years of time trials at WorldTour level where riders use a single chainring without a clutched rear-derailleur and rely on a chain guide to hold the chain in place.

Tony Martin has certainly been an advocate of such gear choices, opting repeatedly for a single 58-tooth chainring on his S-Works Shiv, and rarely been seen to lose a chain in competition. However when he does so he is usually riding on very smooth tarmac 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 wide-range cassette [typically any cassette with a sprocket over 28t] but you happen to be riding on the 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.

Shimano was the latest to bring this to the road market with its new Ultegra RX derailleur.

‘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 current 1x systems are MTB or Gravel products, and it’s only Sram that offers a possible road solution with Sram Force and Red eTap AXS, which happens to also be 12-speed. This can be combined with the clutched XX1 Eagle MTB derailleur. 

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.

Range is not the issue

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 12-30 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 mid-compact 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, that would translate to a difference of less than 10cm of forward movement between them.

The 1x specific 3T Strada, used by pro team Aqua Blue in 2018 season

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.’

Rotor has probably made the case best with its 1x13 groupset, which the brand claims sacrifices only a single effective gear jump compared to a double chainset.


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. The first foray into 1x groupsets by a professional team, Aqua Blue, ended in tears last year when managers blamed the bikes for the struggles of the team.

The Aqua Blue response seemed rather strong, however it is true that a 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 as 12 and 13-speed cassettes become more common.

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.’

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