Power, Torque and Traction
Mon, October 19, 2020 
Belgian Wout van Aert wearing the World Cyclocross Championship Jersey.
A higher gear equals more traction under certain conditions. I learned this driving a manual (Stick-shift) transmission car in the late 1950s. The engine puts out torque, or twisting power, and torque is what moves the car forward. But only if the tires are gripping the road surface, if the wheels start to spin on ice, snow, or soft ground, then torque is reduced to zero, and the car goes nowhere.
The torque the engine produces is multiplied by the transmission, with the first gear (Lowest) increasing the torque the most. Therefore, first gear is engaged when starting out from a standstill as more torque is needed to move the weight of the vehicle. Once the car is rolling, less torque is required so the driver shifts up through the gears to eventually reach top gear, which puts out the least amount of torque, but transmits more revs, or speed.
If the car is stuck in mud or deep snow, the driver can sometimes get out by starting from a standstill in 3rd or 4th gear, thus reducing torque. He then pushes the clutch pedal down to disengage the clutch, revs the engine a little, and then allows the clutch to engage slightly so the clutch is slipping.
In normal circumstances, if the driver were to allow the clutch to fully engage, the engine would most likely stall because the load would be too great. But by slipping the clutch the driver is limiting the power going to the wheels. As the clutch slowly engages, torque is transmitted to the wheels gradually, just enough to move the car, but not applying too much torque so the wheels start to spin.
Now let’s fast forward from what I learned from driving a stick-shift in the 1950s, to what I learned riding cyclo-cross in the 1970s, and bear with me, there is a connection.
I was running my frame building business just outside Worcester in the West Midlands area of England. A good place to be in the bike business, as this area was a hotbed of British cycle racing, including cyclo-cross. From October to January there were events every weekend within easy driving distance.
Business slowed in the winter months, my commute to work on my bike, and a two-mile run on foot every evening was enough training, coupled with a cyclo-cross race each Sunday. I always reckoned a one-hour cyclo-cross race was the equivalent of 80 hard miles on the road. That is what my legs always felt like after a race.
There were all class of riders in these races. Professionals rode with the amateurs, and after a bunch start, the events soon strung out to a procession around a one mile or so course. I was in my early forties and still pretty fit, plus over time I gained a cyclo-cross skill set that allowed me to beat riders who were younger and faster on the road.
Some of the bigger events in the Birmingham area had enough prize money that some professional riders from Belgium and other mainland European countries would come across and enter. These guys were in a different class all together.
On a one mile course I would expect to be lapped at least two or three times during a race by the leading pros. I remember this Belgian rider went past me having caught me on my second lap, he then passed me every second lap. In other words, he was riding at twice my speed.
One time I was passed going up a steady incline through deep mud, I was in a low gear struggling to keep moving, and as this guy went by, I noticed he was on his smallest sprocket, probably 13 or 14 teeth. While my wheels were losing grip, slipping, and spinning, he appeared to be gliding across the top of the mud. Which of course was exactly what he was doing.
I remembered my old driving lesson that while my lower gear gave me more torque, it was of little use if I did not have traction. His higher gear equaled more traction, plus with his speed and momentum he was going so fast there was less time for him to sink in the mud.
Wout van Aert (Jumbo-Visma) leads the GC group on the Grand Colombier (Image: Bettini Photo)I was recently reminded of this story watching Wout van Aert perform in the Tour de France. Setting an unbelievable pace on mountain stages, shelling some of the world’s best climbers out the back of the peloton. (Above,)
Not really considered a pure climber, certainly not built like one. The other thing is Van Aert won several stages in a sprint. Former World Cyclo-Cross Champion, he must have built up a tremendous core strength riding big gears through the mud in the manner I described earlier.
He certainly developed a big engine that produces a lot of torque.
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Reader Comments (2)
Dave,
I've never done cyclocross, but is it along the lines of overgear training? Your comment about 'cross building core strength is interesting.
Hello, Dave! Very interesting post. I am in tune with what you say, sometimes you really need more torque (higher gear, lower cadence) so that you keep traction. The difference here is that Wout Van Aert is one of those riders who like to spin, a lot, he is one of those high (sometimes very high) cadence riders. When the surface is slippery then, yep, he rides as you say, more torque - but overall he is a high cadence rider. Best regards, Mircea