170mm SPEEDHUB for Fatbikes (update)

Yes, the rumors are true, the Rohloff AG are pleased to announce that we finally have a prototype 170mm O.L.D. Fatbike SPEEDHUB up and running.


A bit of background first. What is a Fatbike?:

The Fatbike scene has been growing steadily over the past few years in the US but has been slow to reach acceptance on this side of the Atlantic. Eurobike 2013 put an end to that pace and the show highlighted a vast number of manufacturers who now also include such a bike in their 2014 selection. These special bicycles sporting 4” Fat tires were originally built to enable riders the ability to continue cycling through the depths of winter where thick snow would have otherwise forced them to take a winter-break. The fat tires provide a much larger footprint and enable the cyclist to glide over the surface of soft terrain rather than sinking into it. Although the original concept was for snow bikes, this platform quickly became popular with desert/beach cyclists and swamp/mud cyclists for the exact same reason - the ability to keep going regardless of terrain. This trend kept growing in popularity and here we are today.

The conditions in which Fatbikes particularly excel are unfortunately also the same conditions in which derailleur gears typically fail. An IGH would be a perfect combination but there is one problem – the frame spacing.

To accommodate the fat tires, Fatbike manufacturers have had to choose between an asymmetric rear triangle or a wider spacing to avoid the chain colliding with the tire. Some manufacturers have even increased the almost standardized 170mm Fatbike frame spacing to 190mm in order to accept extra fat 5” tires for extreme snow/sand biking.

Although the axle of a regular singlespeed or derailleur hub can be extended fairly easily, the internal technology of a gear-hub hinders their manufacturers from simply lengthening the axles to fit these new standards. As far as we are aware (at time of press), there are no IGHs available to fit these fatbike frame spacings because of the complexity of such a conversion.

The Rohloff SPEEDHUB 500/14 axle is 20mm in diameter and houses both the indexing and shifting mechanisms of the SPEEDHUB. Although we have investigated various options of enabling the SPEEDHUB to fit a wider frame spacing, this has not been possible to date due to shifting issues arising from the axle slightly flexing and/or twisting due to the extended length. Our new prototype SPEEDHUB 500/14-FAT design manages to avoid these problems and with a little luck, our ongoing tests will confirm the stability and shifting performance of this unit. We will have further details once our tests are completed.


Technical Info to prototype SPEEDHUB 500/14-FAT*:

  • Constructed around the 170mm O.L.D platform (10mm quick-release or M10 threaded/bolt-on)
  • Chainline = 71.5mm
  • Hub shell center-flange distance = 46.5mm
  • 32 hole, disc-brake models only


These dimensions will enable the use of 100mm wide rims and extra fat 5” tires to be used without the risk of the chain catching on the tire. The current prototype design will regrettably not enable current hubs to be converted (as has been rumoured).


*All specifications subject to change. Prices, leadtimes and ETA to be confirmed.

 

More details here: www.rohloff.de/en/products/speedhub_xl