SIN­GLE-MINDED CY­CLING

Af­ter sev­eral years rid­ing the var­i­ous sys­tem and equip­ment op­tions, talk­ing to in­dus­try in­sid­ers and crunch­ing the weight, price and driv­e­train num­bers, what’s the re­al­ity of join­ing the sin­gle-ring cir­cus?

Cycling Plus - - CONTENTS - Words Guy Kesteven Images Michael Kirk­man

No longer re­stricted to moun­tain bikes, we con­sider the pros and cons of drop­ping a chain­ring to sim­plify your shift­ing. Read on to see if you should be join­ing the sin­gle-ring cir­cus...

Sin­gle chain­ring trans­mis­sions dom­i­nate more ex­pen­sive moun­tain bike spec­i­fi­ca­tions and are be­com­ing in­creas­ingly com­mon in the dirt­ier side of drop bar rid­ing, such as cy­clo-cross and gravel. But what are the pro and con re­al­i­ties of go­ing sin­gle ring and will we ever see it send the dou­ble ring the way of the dodo on the ma­jor­ity of road bikes?

Keep it sim­ple

We’re talk­ing just one front chain­ring, with no front mech, no front shifter and no front gear ca­ble. We’re not talk­ing about sin­gle­speed with just one cog at the back. Sin­gle-ring bikes use a con­ven­tional rear wheel and, de­pend­ing on the cas­sette and shifter, you still get up to 11 gears at the back. That can give you a the­o­ret­i­cal gear spread of as much as 511 per cent [the top gear be­ing 511 per cent of the bot­tom one - di­vide 46 by nine, then times by 100] if you go for a rad­i­cal cas­sette like the two-piece 9-46t from E13.

Get­ting rid of an ex­tra ca­ble, chain­ring and front mech is pleas­ing from aes­thetic and mar­ginal aero­dy­namic gain points of view, and get­ting rid of the ex­tra hard­ware re­duces weight, although the scales show that’s not as big a deal as you might think.

Sin­gle rings first be­came pop­u­lar on moun­tain bikes as de­sign­ers strug­gled to fit dou­ble chain­rings, front shifters and chain lines around tyres up to 3in/70mm wide. Ob­vi­ously tyres aren’t that wide, even on road plus bikes, but shorter chain­stays can still make find­ing clear­ance around the chain­stay/seat-tube area tricky.

Dominic Ma­son from Ma­son Pro­gres­sive Cy­cles ex­plains: “Sin­gle front chain­ring sys­tems open up all sorts of pos­si­bil­i­ties from a de­sign point of view. The wide-range rear cas­sette al­lows for a smaller front chain­ring, which means we can

in­crease clear­ance around the tyre where the chain­stays meet the bot­tom bracket shell. This area has al­ways been su­per-dif­fi­cult ‘pack­ag­ing’ wise when de­sign­ing a frame.”

So far only 3T has re­ally ex­ploited the sin­gle ring ‘pack­ag­ing’ ad­van­tage on its rad­i­cal sin­gle-ring-only Strada, fat-tyre aero ma­chine, which gained a load of at­ten­tion at the Euro­bike trade show, and has just been con­firmed as the of­fi­cial race bike for Ir­ish Pro­fes­sional Con­ti­nen­tal Aqua Blue Sport team for next sea­son. This will be high-pro­file proof – or not – of whether sin­gle ring can spin to win at the high­est level.

Just sim­pli­fy­ing the frame mould­ing and re­mov­ing ca­ble guides and front mech mounts on the new Whyte Wes­sex One has saved nearly 100g over the stan­dard frame. In both cases it also cre­ates a bet­ter aero­dy­namic match to that other fu­ture must-have – a wider, smoother rolling rear tyre – as well as a re­ally neat and clean-look­ing chain­set area. Most other com­plete bikes supplied with a sin­gle ring still have space for a dou­ble and front mech.

Shift­ing ease

Go­ing sin­gle ring re­moves the brain strain and trial and er­ror from shift­ing. No more try­ing to work out which gear ra­tio comes next in the se­quence and whether that in­volves shov­ing the chain across onto a dif­fer­ent chain­ring as well as a rear cas­sette shift. In­stead, shift­ing is just a se­quen­tial up or down no brainer with the size of jump dic­tated by the ra­tios of the cas­sette you’ve cho­sen. All the changes can be done with a sin­gle right-hand shifter, mak­ing it sim­pler for new rid­ers to nav­i­gate.

Even though front chang­ers are now bet­ter and faster than ever, hav­ing to shift ring and rear sprocket to hit the next gear in the se­quence will al­ways be con­sid­er­ably slower than a sin­gle rear shift. Us­ing a sin­gle chain­ring also gets rid of the prob­lem of al­most iden­ti­cal, re­dun­dant ra­tios achieved through dif­fer­ent chain­ring and cog com­bi­na­tions.

There’s none of the wear-mul­ti­ply­ing ex­treme chain line or in­cor­rectly set up chain grind of a front mech ar­range­ment ei­ther. Done right, sin­gle chain­ring set­ups don’t drop chains in rougher off-piste/cy­clo-cross sit­u­a­tions like dou­ble/triple ones can. Clutch rear mechs also stop the chain slap­ping against the frame, knock­ing off paint and creat­ing a right racket if

Go­ing sin­gle ring re­moves the brain strain and trial and er­ror from shift­ing

the bike is bounc­ing around. Moun­tain bike use has proved that in­creased con­tact area on chain­ring teeth and chain rollers re­duces over­all wear and tear com­pared to a dou­ble ring setup.

The re­sult is a trans­mis­sion that’s phys­i­cally quiet on the bike and means a qui­eter ex­pe­ri­ence for the rider. From a bike de­sign per­spec­tive, it’s faster for bike man­u­fac­tur­ers to fit, means less parts to or­der and gives more free­dom for fu­ture frame shapes, and it’s par­tic­u­larly well suited to the lat­est gen­er­a­tion of fat­ter tyre gravel and ad­ven­ture road ma­chines. But do you get enough of a gear range to make it us­able for reg­u­lar road rid­ing?

The gear thing

In the­ory, a sin­gle chain­ring setup has half the num­ber of gears of a dou­ble. How­ever, es­sen­tially du­pli­cate gears in dif­fer­ent chain­ring and cas­sette com­bi­na­tions can re­duce the num­ber of no­tice­ably sep­a­rated gears dra­mat­i­cally.

Ian Alexan­der from Whyte points out: “If you flick on the Syn­cro Shift - se­quen­tial gear se­lec­tion func­tion in Di2 – a 2x11 driv­e­train can have as few as 13 use­fully dif­fer­ent ra­tios.” That’s with a princess and the pea at­ti­tude to ped­alling speed too, and the wider your band­width of ac­cept­able changes in ca­dence is the fewer dis­tinct gears you’ll feel. Ex­treme gears such as big chain­ring to big­gest cas­sette sprocket or vice versa are of­ten off lim­its due to front mech or chain­ring in­ter­fer­ence, or lack of ca­pac­ity in the rear mech. The over­all range of gears is closer than you would think with a wide-ra­tio block too. “The stan­dard Whyte Wes­sex is a 50-34 with an 11-32 cas­sette. This gives a bot­tom gear of 28.7in and a top gear of 122.7in. The Wes­sex One is specced with a 44t chain­ring and a 10-42 cas­sette, giv­ing a bot­tom gear of 28.3in and a top gear of 118.8in,” says Alexan­der.

Most of the time, gaps be­tween the gears might not be the ma­jor prob­lem. “A 10-42 cas­sette has three sprock­ets to go from 10-14, while an 11-32 has five sprock­ets from 11-15. Above that, both cas­settes have the same size jumps be­tween them all the way up to the 42 or the 32,” Alexan­der con­tin­ues.

Trans­mis­sion is quiet on the bike and means a qui­eter ex­pe­ri­ence for the rider

Those larger bot­tom end sprocket gaps are fine for steeper, slower rid­ing or where the sur­face/gra­di­ent/speed changes fre­quently. Or if you’re a recre­ational rider not re­ally both­ered about al­ways ped­alling the per­fect ra­tio.

If you’re a time-served, sweet-spot spin­ning racer liv­ing on a strict diet of A-grade club runs, they’re go­ing to feel notchy and jumpy. If you’re that cal­i­bre of rider, you’ll be fine us­ing an 11-36 (four sprock­ets to cover the 11-15 spread and a 33-108in over­all range), 11-32 (fivesprocket 11-15 and 37-108in range) or even an 11-28 (five-sprocket 11-15 and 42.4-108in range). If you’re smooth on the ped­als that’s a 50kph top end be­fore your ca­dence gets too bouncy. If you’re pre­pared to lose top-end sprint/ped­alling de­scent speed you can ob­vi­ously drop the front ring size down to put your close gear sweet-spot where you need it.

The num­bers turn out more favourably for sin­gle-ring when it comes to drag Halv­ing the num­ber of chain­rings doesn’t halve the num­ber of us­able gears

Cash, weights and watts

You’d rea­son­ably as­sume that re­mov­ing the in­nards of your left-hand shifter and los­ing the front mech, in­ner chain­ring and front gear ca­ble would cre­ate a sig­nif­i­cant loss of both weight and cost, but the re­al­ity is sur­pris­ing. The rear mech of SRAM’s 1x sys­tems uses a straight par­al­lel­o­gram X-Hori­zon mech­a­nism rather than a tra­di­tional slant par­al­lel­o­gram, and it has a chain ten­sion­ing clutch. That makes it heav­ier as well as more com­pli­cated and ex­pen­sive to make. Wider range rear cas­settes are also heav­ier and more ex­pen­sive. That means SRAM Force 22 is only 72g heav­ier over­all than SRAM Force 1 and £100 more for the driv­e­train with­out brakes. Ri­val 22 is only 8g heav­ier than Ri­val 1 but £69 cheaper.

The num­bers turn out more favourably for sin­gle-ring when it comes to drag. Spin the cranks back­wards on a con­ven­tional driv­e­train and you’ll feel no­tice­ably less re­sis­tance than a sin­gle chain­ring sys­tem with a clutch mech ten­sion­ing the lower chain sec­tion. How­ever, re­search done by fric­tion re­duc­ing spe­cial­ists Ce­ramic Speed and Di­a­mond­back shows that larger jockey wheels and nar­row/wide chain­ring teeth mean there’s only 1.5-2 watts more drag un­der power with a sin­gle-ring sys­tem. That’s the same lev­els of drag you get from

us­ing ex­treme cross-chain gears in a dou­ble setup.

One for all and all for one?

The ad­van­tages and dis­ad­van­tages you’d as­sume in the­ory aren’t nec­es­sar­ily true in re­al­ity. For a start, de­spite fewer com­po­nents the weight loss of go­ing sin­gle is at best min­i­mal, un­less you in­vest in a very light chain­set and stay away from clutch mechs and wide-range cas­settes. Equally per­versely, sin­gle-ring driv­e­trains cost more than dou­ble-ring equiv­a­lents, on of­fi­cial over-the­counter costs at least.

On the plus side, halv­ing the num­ber of chain­rings doesn’t halve the num­ber of us­able gears. It doesn’t have to mean mas­sive jumps in ped­alling rhythm ei­ther if you match the ra­tios to the rid­ing you do. Most im­por­tantly sin­gle ring­ing sim­pli­fies the process of chang­ing gear me­chan­i­cally and men­tally. It makes your bike qui­eter, keeps the chain on over rough ter­rain, looks neater and opens up whole new tyre and tube shape com­bi­na­tions for de­sign­ers by re­mov­ing the space needed for an in­ner chain­ring, the swing of the front mech and the ca­ble align­ment to pull it.

Whether that’s enough to see it make dou­ble chain­ring set­ups as rare as triple chain­ring ones are th­ese days we don’t know. We do know there’s go­ing to be a lot more equip­ment and bike de­vel­op­ment around sin­gle ra­tio sys­tems, and we are re­ally look­ing for­ward to see­ing where that leads.

Above Top right Right The One saves nearly 100g over the stan­dard Wes­sex frame Whyte specs SRAM’s wide-range 10-42t cas­sette Add a 44t chain­ring and the range is al­most iden­ti­cal to 2x11

Above Top right The Stig loves a bit of rough Nar­row-wide chain­ring teeth se­cure the chain

Top Above Sin­gle ring­ing loses left­hand shifter com­pli­ca­tions Clutch mech and big­ger cas­sette evens out weight with 2x11

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