The Mension Tension Travel System is Moonmen's solution to chain tension. With the increased popularity of single speeds and Internally Geared Hubs (IGH), there are many options for chain or belt tension. Moonmen has worked with many different styles of tension systems including the full range of adjustable dropouts, eccentric bottom brackets and hubs, as well as the retrofit-able choices like the singulator, etc, each style has its positives and negatives. After trying all of these options we came to want something more. Mension, unlike other chain tension means, requires little to no maintenance and does not limit frame design. Putting the tension device in the chain stay, Mension allows the use of any style of dropout and any style of bottom bracket, broadening frame customizability. 

In basic terms the Mension is a Turnbuckle or Bottle Screw. The System features two opposing threads, one right hand and one left hand, back to back so once the 'bolt" portion is rotated the two sides expand or compress in equal measurement. The System is CNC machined from 6/4 Titanium. It has a .6" throw and uses a 5mm set screw that keeps the bolt from rotating once the desired chain tension has been achieved. The internal portion of the chain stays features a precisely machined section just beyond the threads that corresponds with the outer portions of the double ended bolt. This machined section is where the forces put onto the frame are focused. The benefit of this is that the threads never see any strain so as not to damage or deform them under extreme riding.

The Mension System is also dual purpose. It doubles as a travel option paired with a set of tube splitters or a wish bone separator at the seat tube. This means that your bike can be disassembled to fit in a non-oversize, check-able travel case. Many cyclists travel with their bikes. The money saved on the ever increasing airline fees for an oversize bike box makes the Mension System a money saving advantage. Having a removable rear triangle also enables Moonmen to build a different back end on your bike for multipurpose use, e.g.- If you want a single speed specific bike at times but also want the options for gears and racks down the line we can start with a 12 x 142 single speed spaced dropout, remove the chain stay/ seat stay by way of  the Mension system and then fabricate a 12 x 177 for a derailleur option. Two bikes in one. The Mension Tension Travel System is a $600 frame up-charge and adds 200g to the weight of the frame.


All custom bicycle purchases can be made by contacting the fabricator directly. Click here for more information.