The steel chain fades away….

Last weekend I visited the SPEZI and met the guys from SIMPLE is a swiss bicycle manufacturer who developed a carbon belt driven premium bicycle. The SIMPLE bicycles are designed to reduce the maintenance level to a minimum. So it´s a logical approach to use the carbon belt instead of a standard chain. The advantages for city cyclist are:

– No dirty trousers anymore because of chain oil!

– No need to oil the chain. Less maintenance!

– New design possibilities. The chain case is reduced to a stylish spoiler!


carbon belt drive


The modifications on the bicycle frame are minimal. A srew on the rear chainstay allows you to open the frame and to put the carbon belt inside the frame triangel. The SIMPLE bicycle has a mechanical sled on both sides of the dropout to adapt the distance between bottom bracket and rear dropout. This makes it easy to fit in the belt the first time. In case of a flat tire the sled is not needed because there is no big tension on the belt. The depth of the tooth is so high that it accepts a low tensioned belt. 

Here you see how powerfull this drivetrain is:

The optional hubs are the Speedhub from Rohloff and the SHIMANO Alfine.

During the testride I noticed via my legs a smooth feeling! Let´s see how the longterm behavior ot the belt will be! 

The days of the steel chain are numbered. First we´ll see a replacement in the premium city and touring bicycles. Because of the price and the customized frames. But prices for the belt will fall and the bicycle mass market will absorb a new technology!

Gates belt carbon OPTIMIST SIMPEL


Other drivetrain alternatives are discussed in this video… (sorry only in swiss language!).


  1. gear

    When you say that modifications to the frame are minimal then you say that the rear triangle has an opening, can’t you see that those two statements are somewhat contradictory?

    Belts may turn out to be an improvement. And openings in the rear triangle may turn out to be OK in the end (pun intended) but only time on the bike will tell for sure if this setup holds up to the riggers of daily riding.

    In the mean time I would like to hear just one person comment on the ride characteristics of a bike with an opening in the rear triangle as opposed to a bike without the opening.

    • Morgan Patton

      Here is your one person commenting on the ride characteristics of a bike with an opening in the rear triangle as opposed to a bike without… I have been riding both types of frames for a few months now and have been building frames for over 2 years. The difference between having the stays welded, brazed or bolted to the rear drop-outs is undetectable. I can find no drawbacks at all to a frame that splits open.

  2. Hi gear,

    during the design process of a bicycle frame the opening option should be no big effort. To implement such a feature in a existing frame makes no sense!

    I agree that the frame interface must be designed in the right way to withstand the forces who act on this part.



  3. leonwoodbine

    My next Alfine bike will have a belt system for sure. The concept is simple, the parts have been in production for some time (2007 or so) and the advantages outweigh any disadvantages (if there are any). Motorcycles use this technology in daily use on the same roads as we ride with no problems, and that is with vastly more power and speed than our bikes! The time for belt systems is now.
    However, chains are not going away. After 100+ years of development, modern bicycle chains are very advanced and refined. Not to mention the economies of scale producing millions of them! And derailleur systems demand chains, so that alone keeps them around. As much as I love Internal Gear hubs, some bike applications work extremely well with chains/derailleurs. Others, IG hubs and belts are the way to go. Hope to see more belts on bikes!

  4. Zebrauno

    I’ve some doubt about overall efficiency.
    The fact that belts are used on motorcycles is not worth mentioning because with an non-human powered vehicle with 100+ hp you just don’t care about the energy lost in trasmission.

    I’m confident that with a scientific test, putting the two methods on similar conditions driven by electric motors, leaving them running overnight for a week you’ll find that the old chain is more efficient…but for sure it wears faster.

    Anyway, 300 euro for and a kit, for me, is not worth.

  5. spike

    The ultimate proof of the viability of this technology is whether or not it is ultimately adopted by racers. That will settle the “efficiency” argument, for one thing. From the standpoint of everyday practicality, I like the idea, but the impracticality of retro-fitting older bikes means the steel chain will be around for quite a while yet.

  6. hi, i’m the founder of and a big fan of the carbon drive. as for the frame design.. every full suspension frame has links and openings, so having one screw on the real triangle to squeeze through the belt is pretty basic. the real challenge is to have a perfectly aligned frame and a smart enough tensioning system.

    i have been riding the carbon drive for about one year now and love it. but yes, time will tell. 🙂

    • Hello Phil,

      thanks for your feedback. I´am a big fan of the simple-bicycle concept. Long lasting and maintenance free bicycles!

      Can you give us here on hubstripping your feedback and experience on the different internal geared hubs you are using on simple bicycles?

      Do you give a hub maintenance advice to your customers?
      What is your experience on internal geared hub reliability?



    • Morgan Patton

      Hello Phil – I just finished my first frame for the belt-drive application and have been riding it with an Alfine hub. At first, I ran the belt tension quite low and didn’t have any problems. Then, my shop got a belt tension gauge from Gates and I found that I needed to really crank up the tension on my belt according to the gauge. Since I have tensioned my belt, the Alfine hub has been making terrible bearing grinding noises. I took the tension back down and the hub got quiet again but, now when I torque on it, the grinding comes back. I must have caused permanent damage…

      Since you must have experience with both the belt and the Alfine hub, is this something you ran across at all? Do you generally keep the belt tension pretty loose?

      Thank you for any information you’ve got..

      • @Morgan: The tension of the Belt is a Topic in itself. I personally leave the Tension lower then recommended on about 10NM with a Rohloff and I just pulled a Kids Trailer AND Luggage ( around 80kg ) through Switzerland like this. When we deliver Bikes to Customers we keep to the minimum of 15NM. Personally I think this is pretty high and might affect a Hub’s bearings long term. I have not heard of Problems with the Alfine Hub yet. We delivered a respectable ammount of Bikes with Alfine and Belt Drive.

  7. Awesome stuff, I can relate because i did dirty my pants about a year ago, It was very embarrassing,I would not like this to happen to me again.

  8. Greg

    So what’s wrong with a chain and a fully enclosed chaincase?

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