During this past Sunday’s MotoAmerica Motul Superbike race two at Road Atlanta, which took place on a fully wet racetrack caused by the prodigious rains that fell throughout most of the day, a total of six bikes took off-track excursions. And, of those six motorcycles, three of them were able to rejoin the race.
Mathew Scholtz never actually crashed his #11 Yamalube/Westby Racing/Yamaha YZF-R1. He successfully avoided Jake Lewis’ crashing machine, ran through the grass, and got back on track with only a bit of Georgia clay and grass on his Dunlop tires, which the tires shed in fairly quick order.
Roger Hayden crashed in a slow corner, and went down, but he was able to quickly remount his #95 Yoshimura Suzuki GSX-R1000 and get back in the race.
Garrett Gerloff also went down in the wet conditions, but it took him some time before he was able to get going again on his #31 Monster Energy/Yamalube/Yamaha Factory Racing/Yamaha YZF-R1. After more than a lap on the side of the track, Gerloff was finally able to get back under way and rejoin the race. But, what caused the delay?
“Well, for one thing, the chain came off,” Gerloff said. He barely got the words out before I had a flashback to my childhood and my beloved Sears-Roebuck- catalog-acquired bicycle with the red-glitter banana seat, chrome ape-hanger handlebars with red-glitter grips, and towering sissy bar complete with – you guessed it – a red-glitter sissy bar pad at the top.
I loved that bike… until my uncle backed his Oldsmobile Vista Cruiser station wagon over it in my grandparents’ driveway. From that point on, my rat-trap-pedal-equipped freedom machine rolled down the road like a crab on the beach – mostly forward, but also a little bit sideways. And the chain always came off. My uncle had created at least a two-inch sideways offset between the front sprocket and rear sprocket on my bike. It was a minor miracle that the chain would stay on the bike at all, but it did for about three of four circulations of the pedals until the sickening clang and metallic crunch of the chrome chain guard signaled that the chain had left its predetermined orbit.
My grandfather went to the tool shed, returned with a prybar and a sledgehammer, and managed to bring the two sprockets a little bit closer in-line with each other. But, for the rest of the time I owned that bike, the chain coming off was a daily occurrence. I used to tie a pair of black, cotton-jersey gloves around the handlebars, and I would don them to keep my hands clean during the daily chain-reinstallation procedure.
Okay, flashback over; back to Gerloff. When I expressed my amazement to him after hearing about his “chain incident,” he calmly said. “Everybody I’ve talked to thinks it’s a big deal that my chain came off, but it really wasn’t. I had a couple of cornerworkers hold the bike for me, and I slipped the chain around the bottom of the rear sprocket. We rolled the bike forward a little bit, and the chain went right back on. It was the bent brake lever guard that held me up and needed the most work because I couldn’t use the brake until I bent it out of the way.”
You may find it hard to believe that Gerloff was able to re-install the chain on his 200-plus-horsepower Superbike that easily, and we did, too. And, furthermore, if it’s that easy to put a chain back on a Superbike, why don’t they come off more often in a crash? “I don’t really know,” said Gerloff. “But, it is pretty unusual for the chain to come off.”
So, I did my research and discovered that proper chain tension on a racebike is kind of a black art. Race technicians actually install chains a little bit looser than they are on streetbikes, and one of the reasons for that is friction. A loose chain reduces horsepower-robbing friction. The other reason for a little bit looser-than-streetbike-spec chain on a racebike is because it makes it easier and quicker to swap out the rear wheel for tire changes, which is especially important during the Superbike Superpole qualifying sessions when getting that ultra-soft, yellow-sidewall-striped “Q” tire installed quickly is of paramount importance. You definitely don’t want a tight, recalcitrant chain to interrupt the proceedings.
I’ve personally witnessed a team technician install the rear wheel on a Superbike, then place the shaft of a T-handle screwdriver under the top run of the chain, just in front of where the rear sprocket meshes, and roll the wheel backwards so that the T-handle gets caught between the sprocket and chain. That little bit of space measured by the T-handle is the technician’s way of ensuring that the chain is loose enough to spin with very little resistance, yet tight enough to stay on the sprocket at 190 miles per hour and more.
Take a look at photos or slow-motion video footage of the chain-side of a motorcycle, and you’ll see that the lower run of the chain, under the swingarm, is not ruler-straight, but rather, curved and even slightly S-shaped under power. That is the slack in the chain creating a “whip effect.” But, the chain almost never comes off. Not unless a sudden side force like a crash violently moves the chain to the left or right, causing it to no longer be perfectly in line with the sprocket.
So, the chain came off Gerloff’s Superbike. No big deal to him. He put it back on and got back into Sunday’s race.
Meanwhile, I’m still having flashbacks about that sweet bike that my uncle backed over in my grandparents’ driveway. The grease may no longer be lodged under my fingernails, but the unpleasant memories are definitely still lodged in my brain.