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Under-Tail Exhaust: Almost Gone and Good Riddance

Form after Fashion


Under-Tail Exhaust

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.)

03 HYPERSTRADA 300x224 photo

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.


Categories: Editorial, Motorcycles  


  1. M
    Posted on: December 3, 2012 4:51 pm

    I have two bikes with undersea exhaust, a Ducati Hypermotard and aKTM 950SE with undersea exhaust.

    What’s the problem? I don’t experience any of the BS this guy is writing about.

    Get a life!

  2. Jermaine M
    Posted on: December 1, 2012 9:49 pm

    I’ve questioned the under-tail exhaust myself but I think the majority of the reasons he lists are idiotic and based off personal bias. I could approach this many different ways, but to keep it short, lets look at the best of the best. What do just about all GP bikes have in common? Under-tail exhaust and it’s been that way for about a decade now! By the way, that includes Suzuki. Given the GP climate and the fact that they are prototype mechines and the fact that millions are spent on development, don’t you think that would have changed that by now if it was such a big concern? Since there are so many performance gains to be had by a traditional exhaust, why hasn’t suzuki been dominating all motorcycle racing? Interesting stuff there. I agree that it may be a fad more or less, but motorcycles are designed to be beautiful machines. If putting giving a bike an under-tail adds 2pts in looks but subtracts .02 pts in performance I say go for it. Last but not least, I think the Panigale seems to solve both issues, low and centered exhaust with the sleekness of under-tail. It’s just a few seconds off pace in WSBK at the moment…

    • Afletra
      Posted on: January 31, 2013 9:50 am

      GP bikes that use an undertail exhust also have a side exhaust; Desmo, RC, you mention. Have you see any of mass-production bike with those exhaust style? No…
      That’s explain everything :)

  3. Michael Veilleux
    Posted on: November 26, 2012 4:03 pm

    I got one of the first 916′s,production #272. I had read at the time that it was decided to do this for the expediency of wheel-tire changes during endurance racing. With out a single sided swing arm I always thought it made no sense. My 98 cyclone M2 has a under engine exhaustcan, nice but increases engine hight, therefor the center of gravity. Which makes the bike top heavy.
    Kudos to the suzuki engineers for not adhering to the nonsense.

  4. Rob Brooks
    Posted on: November 22, 2012 8:39 pm

    Well said in the blog, Marc. I used to think underseat systems looked cool, clean. I’ve never ridden with one, but I almost bought a Yamaha FZ6, which had that setup. Glad I didn’t. A couple of friends have ridden with bikes that had underseats, and they made the same observations you did- heat too great for passengers, tended to cook straps of tail bags, etc. Not good. Both my current bikes, a Yama Royal Star TC & a Kawa ZR-7s, have low pipes/cans, which I’ve come to agree is mucho better.

  5. Rocket Punch
    Posted on: November 20, 2012 7:29 pm

    “Adding weight, far back and high up on the bike, was anathema to the idea of mass centralization…..”

    This is that exact thing that I try to explain every time I said tail-exhaust is stupid and it is, for the most part, done as a marketing tool to create the so perceived “clean Looking” bikes. Honda is probably the prime offender here not because they use that design, but because they PREACH (an continue to preach) “Mass Centralization” in their marketing speak since day 1 and obviously completely ignore the fact that the design is the most non mass centralized design ever. My 06 CBR600RR is easily the most top heavy ss bike I’ve owned and when compare to any ss bike I’ve ever ridden; Well I guess if you give it a sharp enough rake angle, eventually you can make anything turn……

    The thing is, all this crazy talk only bother those number nerds. At the end of the day when 85% of consumers buy motorcycle base solely on looks and will take any big words that manufacturers throws at them on a brochure without questioning them; They don’t really care.

  6. Rob Brooks
    Posted on: November 20, 2012 5:56 pm

    Good word, Marc. I used to think under-tail exhaust systems were cool and clean looking, but I have friends who own bikes with them, and the very issues you describe in your post, they have dealt with themselves.
    I think I’ll stick with side or belly exhausts on bikes.