Under-Tail Exhaust: Almost Gone and Good Riddance

Form after Fashion

I just got in from a 150-mile jaunt on an injudiciously modified Triumph Daytona 675—a machine I dubbed the “farkelbike” the first time I saw it. It’s actually a pretty neat piece. Seriously hard-core, yes, but the modifications have not ruined it, which is always slightly amazing. Along with the usual visual bits, the Daytona features a full Arrow exhaust and a Power Commander. They combine to make the bike “loud and rich,” which always reminds me of when Loudon Wainwright and Richard Thompson played together.

I don’t mind either aspect of that, except that my Kriega backpack and Aerostich fairly reek of exhaust fumes—and will likely remain that way for days to come. Blame that result on one of the dumbest fads ever to insult motorcycling: the under-tail exhaust.

Manufacturers began toying with the under-seat exhaust in the 1970s, mainly in racing. Suzuki began migrating the exhausts of the square-four RG500 toward the tailsection in an effort to gain some useful length without having to curl the exhaust. In time, the idea of the under-tail exhaust gained momentum, whipped through the Italian design community like a prairie fire. Once Ducati put it on the iconic 916, its celebrity was assured. It didn’t take long before this abomination somehow gained racing pedigree. Ducati has it, Ducati wins races, therefore under-tail exhaust wins races. (Some dogs are brown, my dog is brown, therefore my dog is some dog. It’s the same distorted logic, you see.)

[ See how a low exhaust makes room for useful luggage, as on the new Ducati Hyperstrada?

By the early 2000s, most of the major sportbike manufacturers had succumbed. Honda’s CBR1000RR and 600RR got the setup, as did the Kawasaki Ninja ZX-10R and Yamaha YZF-R1. Hell, even the poor Honda 919—clearly not a leading-edge sportbike—had to suffer with it. (Worse, even, was the poor Honda 599, which got an even uglier asymmetric version.) Each time an under-tail exhaust arrived, it took a toll in weight, performance and practicality. Aren’t we all tired of having our asses fried on a summer day? Wouldn’t it be nice to be able to strap on luggage without the chance of burning your stuff?

The notable exception here is Suzuki, which never did fall for the under-seat exhaust on the GSX-R. I had an interesting interview with Suzuki engineers in 2005, who stated categorically that a traditional under-engine exhaust was ideal, though they wouldn’t come right out an accuse their competitors of succumbing to fashion. According to the engineers, a more traditional exhaust was long enough (for an inline-four), could be made considerably lighter, and had sufficient volume when combined with a chamber under the belly to do anything they needed an exhaust to do. Adding weight, far back and high up on the bike, was anathema to the idea of mass centralization, an effort that prompted considerable engineering effort to reduce things like headlight weight and subframe mass. The Suzuki engineers were too polite to openly scoff at their competitors, but the point had been made: under-tail exhaust is dumb, and we’re not doing it.

I loved reading the technical explanations that came with each new under-tail system, justifying the decision with specious engineering advantages and roundly ignoring the shortcomings. Much of it was pure, unadulterated bullshit. We in the press knew it, and many of the engineers knew it, too. But somewhere a marketing weenie had made the case that in order to be competitive, you had to have the latest. Marketing people have no business in product planning. Shut up and let the big boys work, eh?

I think we’re finally at the end of this style-driven dead end now that Triumph has moved the exhaust to the belly in both the Street Triple and Daytona 675. Only the long-in-tooth sportbikes today still have the “technology.” Hell, even Ducati’s abandoned it in the Panigale, Multistrada, and all the new product we’ve seen for 2013. I give Ducati's Claudio Domenicali full credit here, as he's the first one to call BS on technologies followed because "we've always done it that way." I can imagine the Ducati styling department's overwhelming relief that it no longer has to make "upside-down" tail sections look good.

So, without Ducati's support and the rest of sportbike-dom turning away, I think we can stick a fork in the under-tail exhaust.

Not a moment too soon.