Derailing the Carbon Drivetrain

Aug 28 2007

Sometimes, I find myself faced with crises of purpose. What am I doing here? Why can’t I figure out what I want to do with my life? Will I ever find something that satisfies me? It’s enough to really get me down sometimes. It’s a good thing I’ve got the boneheadedness of the bicycle industry to set me right again.

I suppose it was only a matter of time until some high-watt decided to apply the word “carbon” to drivetrains, and it’s a good thing the folks at Carbon Drive Systems did just that – otherwise I would have mistaken their “innovation” for a glorified fan belt. Anyway, it’s about time someone beefed up those flimsy polyurethane straps – they last a mere 60,000 miles while running in my car. With the glut of other unsuccessful belt-drive bicycles out there, it’s clear to see the addition of carbon fiber must do something to make this product newsworthy – perhaps by making it laterally stiff yet vertically compliant!

And really, isn’t a revamping of the single-speed drivetrain long overdue? I mean, it’s just so hard to maintain that single cog, single chain ring and chain. Sure, when it gives you 20, or even 30 gearing options, a chain drive is worth the painstaking process of applying a coat of lubricant, turning the crank a couple times, then wiping it clean. But when you’ve only got one gear, the reliability, adaptability and near-perfect efficiency of a chain drive simply can’t make up for the extra weight and apparent mud shedding issues.

One of the nice things about attending a college with an engineering school is that you get to dissuade people from pursuing a lot of really silly ideas. Occasionally, you you get to see something cool (though that’s not really how bike balance works) but for the most part, you just shoot down bad ideas. Overlooking than the general sensation of pedaling through sand, the belt-driven protoype I rode slipped under power at low revs, and derailed entirely at the cog around 100 RPM. Good thing none of these will ever be an issue on a singlespeed MTB

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9 Responses to “Derailing the Carbon Drivetrain”

  1. spokejunky August 29, 2007 at 6:28 pm #

    Yeah, but imagine this carbon drivetrain mounted to a NuVinci:

    http://www.cyclingnews.com/tech.php?id=/photos/2007/tech/news/01-31/NuVinci_cutaway

    hub, while riding my white carbon commuter, listening to my mp3 shorts:

    http://www.pearlizumi.com/product.php?mode=view&product_id=758231

    sloshing down my Starbucks with my coffee mug:

    http://www.somafab.com/morningrush.html

    all the while emailing my friends on my bike mounted blackberry:

    http://www.ram-mount.com/index_files/ramb149zaq2.jpg

  2. Kevin August 30, 2007 at 11:12 am #

    ^^

    Sweeeeeet… Now THAT’S how to ride a bike…

  3. gtveloce August 31, 2007 at 8:46 pm #

    Setting aside the carbon marketing spin, I’ve no problem with people investigating alternative drive chain methods. Although as Phil has pointed out this is hardly new. The Johns Hopkins research (original source article here with more pics) doesn’t compare belts with chains, and I’m no engineer, but however elegant chains may be they are made from many, many more moving parts than a belt. All of which pose frictional, wear and lubrication challenges.

    From a practical point of view removing one row of cam-drive chain from a car engine will release 3-5 additional horsepower and allow the engine to rev more freely. Replacing the chain with a belt appears to also release a few extra horses and will definitely reduce maintenance. The chain in my old Alfa is a wonderful, noisy and fiddly thing to adjust, but the belts in modern cars need no adjustment or lubrication, are quieter, last longer and are replaced ‘just in case’. They also retain cam timing spec far longer, which keeps the engine within exhaust pollution standards.

    But there’s little in common between a car revving to 8,000 rpm and delivering umpteen kW and a bike rider spinning at 100 rpm. Other than the inevitable chain stretch, the need for lubrication, wear and quite frequent replacement. A belt drive may or may not be more efficient but it will require less maintenance, is simpler and will probably last forever.

    Combined with hub gears or some other gearing method belts may well have a big future on bikes. Or maybe shaft drive will deliver even greater benefits? Mind you, the UCI will probably ban it anyway.

  4. gtveloce August 31, 2007 at 8:50 pm #

    Of course it wasn’t Phil who said that, I’m just losing my mind and confusing my bike bloggers. But I still think belts are interesting ;-)

  5. frank scurlock September 10, 2007 at 12:04 am #

    Would dig passing on some “real” information about the belt system. Geez, rough crowd in here.

    Frank Scurlock
    Carbon Drive Systems

    frank@spotbikes.com

  6. nmanhipot May 12, 2009 at 2:16 pm #

    Well, I’m late to the party, but I found this article, so possibly others might as well.

    Belt-driven drive-trains are poorly designed and doomed to mushy performance, skipping and derailing?

    Perhaps we’re forgetting the “real world”. The world that exists outside of cycling. Granted, you can’t find rider weight limits on frames, forks or saddles and companies won’t allow their products to be tested against one another, but I’m looking forward to internally-geared belt-driven bicycles.

    After reading all the bad press on polycogs for bicycles, I was surprised to see nothing but belts at the Harley-Davidson showroom taking the full wrath of 96 cubic-inch heavy-breathing fire-bellies. Oh, and the dealer said they’re good for at least 60,000 miles. Go ahead and complain, if you must, but handmade leather polycogs graced the giant flywheels of the earliest motorized bicycles and are still going strong today. I for one am looking forward to a very low maintenance drivetrain, as opposed to having to replace chains two or three times per year, cassettes once or twice per year and chainrings every other year.

  7. walter August 20, 2009 at 5:42 pm #

    @nmanhipot
    Don’t compare motorcycles to human powered bicycles. The former have almost unlimited energy, the latter have to be extremely efficient. What works perfectly on a motorcycle, can be unacceptable for a bicycle.

    As for the carbon drive, the problem is in gears. Hub gears simply waste to much energy. An don’t get me started about the NuVinci…

  8. ZigaK August 28, 2009 at 5:52 am #

    What about Rohloff hub gears?
    http://www.rohloff.de/en/technical/efficiency/
    apparently it has the same efficiency as the standard transmission

  9. beats May 10, 2011 at 6:50 pm #

    Nice posting! I cling on to listening to the reports.I like that there’s a keep a copy system of an elastic wire and magnets holding the pin mechanism in place.Beats By Dre

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