This is cycling, or something very like it. I’m sat upright, so the rider behind me can shelter. My feet are tracing lazy circles, my knees passing close to my wrists as my hands grip the swept-back bar. We’re travelling at close to 30mph, but I’m hardly putting any force through the pedals. There’s no need. Inside the bike frame is a 90cc two-stroke engine, buzzing away like a wasp’s nest that’s just been poked with a stick. Welcome to the world of the derny bike.

If you’re a fan of the keirin you’ll have seen the derny. It’s the moped-like bike which brings the train of sprinters up to speed before peeling off and letting the riders fight out the final few laps. That’s a bit of a walk-on part, but, as I’m finding out, the derny can be a star turn. I’m at London’s Herne Hill velodrome to learn how to ride one, and to find out a bit more about the derny’s history.


My instructor is Graham Bristow, promoter of Herne Hill’s Good Friday track meeting ( and one of the country’s most experienced derny pilots. Although keirins give the derny an airing on TV, it’s motor-paced events in which pairs of derny pacers (or drivers) and cyclists race against each other which get Graham excited.

“In a race, the pacer is the brains and the rider has to do as he’s told,” he says. “A good pacer will get an average rider into a good finishing position. A bad pacer can lose a good rider the race.”

Radio silence

There’s a lot more to it than just cracking open the throttle and hoping the rider can hold the derny’s wheel. “If you’re racing on the rivet and someone’s cork pops – that’s it – they’ll never get back on the derny bike’s wheel. You need to know when to ease off a little bit,” says Graham.

With no radio communication between pacer and rider it pays to talk tactics first. “You have a conversation with the rider beforehand, especially if you haven’t trained with them before the race.”

Even the loudest shout is hard to hear with several derny bikes racing, but if the rider can make themselves heard, they can ask their pacer to speed up or slow down. “Riders shout ‘Allez!’ if they want to go faster,” says Graham. “I warn my riders, ‘Be careful what you wish for!’ Sometimes pacers will give a signal behind their backs, but the trouble is the other teams can see.”

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Graham’s approach is simpler. “Before a race I say, ‘Keep your wits about you, when I go we go!’”

Just like in regular track racing, attacking from the back of a group can be effective. “If you’re going from the back, you need to go quick. Come off the banking and hit them hard.”

Graham takes a lot of satisfaction from working as a team. “Pacers should never race each other – you need to race for your rider. At the end of the race, if you can say you got the best out of your rider, then you’ve done your job.”

Derny bikes have more macho relatives. Graham simply refers to them as “the big bikes”. Forget bicycles with engines, these are proper motorbikes modified for motor-pacing. Graham asks me if I want to take a look. I’m grinning like a schoolboy as he shows me a 650cc Triumph Thunderbird.


Little and large

Next to the little derny the Triumph looks huge, with its chopper-style fork and roller at the back to stop a cyclist being spat skyward by the rear wheel. Graham stares at the Triumph with pride. “Only about 200 of this model were made,” he tells me, “and 10 were converted to motor-pacers for the 1982 World Championships in Leicester.”

Nine of those are still in working order, most at Herne Hill. Controlling one looks a challenge, let alone taking the responsibility of racing one with cyclists around you. The track Triumphs have been modified for riding stood up, giving the best possible shelter for the cyclist behind. The pilot or driver holds on to the huge handlebars, leathers billowing and punching a huge hole in the air.

Like the derny, these big machines have no electric starter. In fact there’s not even the kick start you might expect to find on a big motorbike. Instead, the Triumph must be bump-started by running along, leaning on the bike to stop the back wheel skipping, then letting the clutch out. It looks like a quick way to give yourself a hernia.

That’s not the only old-fashioned thing about these bikes. “There’s no speedo,” Graham explains, “the pacing is done by feel. Everything needs to be very gradual. Give a handful of throttle and you’ll leave the rider behind. But you can’t be frightened of this thing – it knows…”

The big bikes need special bicycles – ‘stayers’ – to ride behind them. Graham shows me an old steel stayer with a huge chainring, small front wheel and what looks like a back-to-front fork.

“Stayers tend to have a big gear of around 116 to 132 inches,” says Graham. To put that in context, a 53T chaining/12T sprocket is 115in. The smaller front wheel ensures the axle sits at the same height as the big bike’s roller. That way the wheel hits it squarely and is knocked back rather than up. Graham says that the wrong-way fork makes for better stability when touching the roller, but it still looks like an accident waiting to happen to me.


The wheel itself looks to be all tyre. “The tyre is bandaged onto the rim,” says Graham. “It gives the rider a better chance of staying on if it punctures.” That settles it. I’m up for trying a derny, but maybe a session on the stayer can wait.

“You’ve ridden a motorbike, haven’t you?” Erm, no. “But you’ve ridden on a track before?” Erm, nope. I think that Graham is going to be in for a difficult afternoon. Before we get out on to the velodrome, I need to get the derny started. I’d assumed there’d be a kick start, even on such a retro-looking machine, but no. The bike needs to be bump-started.

Graham shows me the technique. He runs along, hip on the saddle, pulls the clutch in and out and the 90cc Puch engine springs into life. Easy.When I try to do the same, nothing happens. By the fourth of fifth time, I’m getting quite tired.

Another derny is wheeled out, which Graham’s friend Tony promises is easier to start. I run hard, pull the clutch lever in and out, and at long last the engine comes to life. I jump on as quickly as I can, convinced the bike is about to head towards Dulwich without me. Unlike a motorbike, the throttle is controlled by a lever on the handlebar rather than a twist grip, and I practise accelerating and decelerating, riding in a big figure of eight to get used to the feel. I manage not to hit anything, so Graham decides I’m ready for the track.

On track mind

My mind is racing. Graham warns me that the wind has picked up, with some words of advice about when to open the throttle and when to back off to hold a consistent speed. I’m not sure I take it in. Mercifully, he starts the bike for me; all I have to do is open the throttle and turn the pedals.

I’m off, up on to the banking. I squeeze the throttle lever with my finger and the bike shoots forward. For anyone who has ridden a motorbike this probably sounds ridiculous, but this little 90cc derny feels surprisingly fast.

I try to stay smooth and steady around the first banked turn, then open the throttle wider down the back straight. I’m up to 35kph. Yes, I know that doesn’t sound like much but I feel as excited as a kid who’s just ridden without stabilisers.

After a few laps Graham calls me in. I might as well drag my feet on the ground, Flintstones-style, for all the effect the brakes have. Arse, I’ve stalled it. “Would you like me to start it for you?” asks Graham. I’m determined to get it going myself, but fail again. I’m almost on the back straight by the time Graham puts me out of my misery.


Now things are going to get more interesting. Tony is going to ride another derny, while two track cyclists hold our wheels. I’m no longer going to be wobbling around on my own, but pacing with a rider just a fag paper’s width from my rear wheel.

I undertake my rider, and he sweeps down off the banking to grab my back wheel and we’re soon lapping at 45kph (28mph). The derny feels more stable at this kind of speed. It wants to go quickly.

The wind makes a surprising difference, so I can’t just set the throttle and lean to the left twice a lap. The throttle is very sensitive, too. A little too much and the bike shoots forward. Back off too much and it coughs and splutters.

Tony on the other derny slides past us, the rider behind pedalling furiously. He pulls away for a while and then the gap holds steady, and we ride in noisy formation as the sun sets over Herne Hill.

Lap after lap becomes almost mesmeric, but it’s getting dark and Graham’s lap counter spins down from five to zero.

The brakes are still hopeless, but this time I don’t stall. The engine is still buzzing, and so am I.

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