Bionicon is introducing their B-Boxx internally geared crankset at Eurobike today. Similar to SRAM’s Hammerschmidt (see our post on that here), the idea is to replace the front derailleur in order to allow more freedom for frame design in AM, DH and Freeride bikes. Using this, frame designers can focus on optimal suspension and pivot design without compromising anything just to fit a front derailleur in there. This idea hatched in 2004 with Bionicon founder Andi Felsl meeting up with Universal Transmission/G-Boxx founderÃ‚Â Kalle Nicolai after Eurobike 2003. Click on the pic above to expand the view.
See more pics, specs and how it compares to HammerSchmidt after the break…
Put simply, the B-Boxx is a shiftable planetary drivetrain that uses a push button mounted on the handlebar to shift the patented magnetic operation. Download a WMV vid showing how that works here.
To clarify, “ISCG” is Int’l Standard Chain Guide mount, which is the same way the HammerSchmidt mounts, so your bike has to have these mounts built into the frame.
The production version has a gear ratios corresponding to a 22-25 tooth low gear and a 36-41 tooth high gear. The lower gear is driven directly (ie. 1:1), whereas the higher gear has a 1:1.65 ratio, so the crank is actually spinning 1.65 times faster than you’re pedaling.
So, how does this stack up to HammerSchmidt? Well, with the limited early info, there are only two discernable differences:
First, the B-Boxx uses a magnetic arrangement to activate the pawls that engage the higher gear, whereas HS is mechanically activated by cable. Second, the gear ratio is just slightly different…the HS is 1:1.6 versus 1:1.65 on the B-Boxx.Other than that, the systems are very similar. It’ll be interesting to see which mechanism is more durable in the long run.