Exclusive: Cranklock system delivers massive corner speed advantages for racing cyclists
By Loz Blain
July 22, 2009
Seconds are everything in cycle racing. A 10-second gap on the nearest guy behind you means he's got to work his butt off just to stay in touch. So a device that can reliably give you an effort-free 20-second advantage on a 3km twisty downhill stage is clearly going to be dynamite in the racing market. It's called the Cranklock, and it allows cyclists to enjoy motorcycle-style lean angles and massively improved cornering speeds by putting your center of gravity low and to the inside of the corner, like you can on a motorcycle. And if initial reactions from pro racers in New Zealand are any indication, it's going to revolutionize the world of competitive cylcing. Oh - and there's safety and security benefits for your average road rider, too. This is a sensational idea.
The cornering problem
Motorcycles and bicycles are very similar from a dynamic point of view - inline two wheelers, with a seat for the rider and steered through a handlebar. And yet riding them downhill through a set of corners is a very different experience.
If you're on a motorcycle, you can achieve huge corner speeds using massive lean angles that let your knees (and sometimes elbows) drag along the road. But on a bicycle, with essentially the same setup, you're forced to brake a lot earlier and go much slower, with a greatly reduced lean angle. But why?
The answer jumped out at New Zealand-based inventor Chris Toal as he remembered his Superbike racing days. "I was taught by a world champion, and he taught me that you've gotta get your weight on the inside of the bike, as low as you can, and that's where all your cornering comes from. So you push down with that inside foot, and then you just gently adjust with your handlebars."
But on a bicycle, it's impossible to get that weight down low onto your feet, because your feet are resting on moving pedals. Instead, you support yourself between the seat and handlebars, which moves the bike's center of gravity right up - and causes the bicycle's handling instability.
Finding a solution
This set Toal's creative mind off on whether a solution could be found - obviously, you can't put a set of motorcycle-style footpegs on a pushbike, because they'd foul the motion of the crank. But what if you could temporarily lock the crank in place like a temporary set of footpegs as you went into a corner? You can't pedal in a tight corner anyway - could a locking crank be an answer to allow motorcycle-style cornering on a pushbike?
Toal built a crude prototype, welding washers to his bicycle's front sprocket and simply firing a pin in to lock it. To test the pure cornering theory, he got a few riders together and ran a series of timed trials on the twisty downhilll section of road leading to New Zealand's Piha surf beach. The riders coasted all the way down the hill, so there was no advantage for the stronger pedallers, and the tests were repeated many times with the crank locked and unlocked.
By the end of the day, the advantage was becoming very clear. With the crank locked, riders were covering the 3km downhill twisty stretch an average of 20 seconds faster, purely because of how late they could brake and how much extra speed and lean angle they were carrying through the turns. The bicycle was handling like a small motorcycle.
"You ride past the 'I am going to crash' point, and you lock it, and put your weight on it," says Toal. "And as soon as you put your weight on it, the bike does this weird thing. It feels like you've stepped off your bike onto some sort of scooter - 'cause it stops wobbling. Because all your weight goes from up high in the bike, and balancing between your arms and the wobbly pedals, straight down to your feet. So exactly when you need it, in the middle of the corner, your center of gravity drops down around your feet."
Junior downhil MTB racer Brook Macdonald (1st Junior DH, 2008 MTB world cup, Australia, 1st Junior U19, 2009 NZ Raboplus National Championships) simply says "It's sick." Sick meaning "really, really good," we understand.
"Within a minute and a half, he was trying to ride it around in a circle in the carpark and get the inside handlebar to touch the ground," Toal says.
Likewise, NZ motocross and BMX champ Blake Gillard simply said: "It's awesome."
Thirteen time NZ national speed cycling champion and two time Commonwealth games team member - and bicycle engineer - Justin Grace was a little more forthcoming. "Cornering speed can be dramatically increased. Turning circles can be tighter. This will likely revolutionize the cycling world, from BMX stunts, Downhill and Road."
The Cranklock system
The Cranklock system works by simply giving the rider a lever to press to lock the crank. The crank will lock at any 90-degree increment from vertical - so you can lock it with the pedals straight up and down, or with them horizontal.
Toal recommends you lock it just as you are about to enter a corner, with the inside foot leading. You then put your bodyweight on that inside forward peg and turn the bicycle like a motorcycle, enjoying the additional lean angle and corner speed, before releasing the lock and pedalling out on the exit.
Using the system, he says it's not just a speed advantage - you've got a much better body position and centre of gravity to correct the bike if it loses traction, and because you're slowing down so much less for the corner, you don't have to put in as much effort to get your bike back up to pace on the exits.
There's also an in-built security device - you can lock the crank with a key when you leave the bike unattended, making it useless to bike thieves even after they've cut your bike lock.
Toal estimates that if the Cranklock is built into the manufacturing process for new bikes, it should cost around NZ$40 to add in, and is unlikely to raise the retail price by more than NZ$100. He's also working on a retrofit system to sell as an aftermarket add-on into the enormous cycling market.
It's currently illegal in road racing and certain triathlons, but Toal is working on having the technology evaluated and approved for road racing by UCI Switzerland.
Certainly, if it's as effective as Toal says it is, crank-locking systems are going to be a massive force in races like the Tour de France, where there are numerous hair-raising, high speed downhill sections featuring treacherously tight corners. If it gains roadracing approval, and the results back it up, you'll see a Cranklock on pretty much every competitive racing bike - and the system's very effective on a sliding or jumping MTB or BMX as well.
A business opportunity
We reckon Mr. Toal is on to a winner - and, being big motorcycle fans, we'd love to try it out! If it really does deliver a motorcycle-style cornering experience, then it could have quite a serious flow-on development effect - will bicycle road tyre technology have to improve to give the extra levels of side-grip you'll need for these huge corner speeds? Will tyre profiles need to change to allow you to put rubber on the road at angles you never needed before? It'll be fascinating to see.
Chris Toal is looking for business partners to start working on licensing the technology throughout the cycling industry, as well as setting up the manufacture of aftermarket Cranklock systems. If you know of anyone who might be interested, he can be contacted through the Cranklock website. He's also working on some other very exciting technologies too, that we hope to bring to you within the next few weeks. We wish him the very best of luck.
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