Introducing VECTr

The light-weight, efficiently simple, interchangeable expanding gear system for bicycles.

VECTr - Variably Expanding Chain Transmission

VECTr – Variably Expanding Chain Transmission (Patent pending)

The system eliminates:

  • Chain droppage due to changing between discrete chain-rings.
  • Chain wear due to rubbing and friction of front derailleur.
  • Chain stretch due to small to large gearing differences between front and rear gears.

The system allows a rider to

  • Change gears as quickly and easily as standard chain-ring/derailleur systems.
  • Choose among five crank-mounted gear settings from 24 to 44 teeth equivalent.

The system could easily be adapted for both front and rear gearing applications.

What is different about VECTr:

Expanding chainrings have been around for over 100 years, but they have been complicated and so, heavy and expensive.

The weight of the current version of VECTr  (in steel) compares quite favorably (500 g) to the triple chainring and derailleur it replaced (475 g).  When VECTr is commercially manufactured, its weight certainly will be reduced.

When compared with other in-line transmissions with regard to weight versus cost, VECTr is clearly superior:

Product MSRP Weight
VECTr $150 – $200 525g (steel)
NuVinci 360 $399 2450g
Patterson Drive/FSA Metropolis $300 1734g
Rohloff Speed Hub $1100 – $2000 1700g – 1825g
Shimano Alfine 8sp $360 1600g
Shimano Nexus 8sp $280 1500g – 2000g
Schlumpf Mountain Drive $700 1080g
Sturmey Archer SRF5  5sp $181 2010g
Truvativ HammerSchmidt $700 1623g


The reliability and performance of VECTr is being improved as the design is modified and tested.  It will outperform triples in having more gear settings, and in maintaining a consistent chainline.  It is more complicated (six moving parts) than triples (one moving part (the derailleur) and three relatively stationary chainrings). But, this is offset by the greater reliability of preventing dropped chains.

If you are interested in learning more, or being notified of updates, e-mail us  at

  1. Todd Fahrner says:

    You posit benefits relative to standard derailleur systems. What benefits if any do you see relative to internally geared hubs? I suppose both technologies could be combined to increase range, but you’d still need a chain tensioner preventing chain enclosure.


    • Todd Fahrner says:

      The video demonstration would be more effective if you installed at least a left pedal, so you could use it as a handle to turn the cranks smoothly. The lack of a handle/pedal makes the mechanism seem less smooth than it may in fact be.

      Also the fact that the mechanism is not installed on an actual bicycle seems to invite the question: does it work at all with real torque loads? If not, would the required structural changes interfere with the operating principles?

      Concerning chain wear (“stretch” a misnomer), seems to me that the load being distributed over fewer teeth/links than a continuous chainring would accelerate wear.

      And then there are the “Biopace” controversies to hash out!


      • Joe Magee says:

        Thanks for the feedback.

        I will have to improve the video. This is just a working model, so it is not as smooth or polished as a developed prototype would be. I hope it makes apparent the advantage of preventing chain drops by keeping the chainline constant, but allowing more gearing choices that 3 chainrings.

        I hope to do road tests when the weather allows, but I expect it will support real torque loads.

        Reduced chain wear is of lesser importance. But while the five teeth of each gear segment may increase wear on those links because of heavier load, there are six or seven links suffering no wear. The extra-wear on some links will pass around the chain, so overall there is not increased wear, or it is minimal. Think of it this way: VECTr only has 20 teeth which engage the chain, so chain wear will be the same as always running on a 20t ring, but the rider will have the advantage of 24 to 44 tooth equavalent gears.

        The “stretch” it may eliminate is from running between a small cassette cog and a small chainring or large and large. (If an experience cyclist would not have this problem, fine. But w/ VECTr front and rear, there is no problem to avoid.) Again, eliminating stretch is not its main advantage.

        It is not intended to approximate oblong or oval chainrings, but others have seen that as an advantage. It does seem, though, that the square-ness of the chain path when VECTr is in expanded position (lumpiness) will not be as noticeable since larger gears are used on downhill or level roads when the pedal momentum is at play, and crank loads are not heavy.


    • Joe Magee says:

      The main advantages over internally geared hubs and front gear boxes would be price (comparable to current chainrings), weight (same or less than chainrings) and compatability (attaches with 64 mm BCD on whatever BB). It would still need a tensioner, but if VECTr were installed instead of a rear cassette, the tensioner would certainly weigh less than a rear derailleur as it would need only one wheel and a simple spring mechanism.


  2. Steve says:

    Could you also have it make an oval shape? Like what Rotor does with their Qrings.


    • Joe Magee says:

      I suppose you could. The teeth on two of the gear segments would have to be offset from the locking bolt more than they are now. I understand that there is no consensus on the advantage of oval shaped chainrings, though.

      Liked by 2 people

      • Todd Fahrner says:

        I think the consensus is that non-round chainrings can help somewhat with people who have poor pedaling technique, as from lack of practice. So not a bad thing on bikes for very casual, occasional riders. Flipside is that those who do pedal well (faster and smoother), or who want to learn to, find it annoyingly limiting, compensating for a problem they don’t or won’t have.


  3. JT says:

    Most of my riding is offroad so how this works or not in muddy conditions would be a major concern for me.


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