BobB’s Rotundcycle

I’ve kept frame #21 a secret since MT was going to surprise her hubby BobB for his 60th birthday with a custom fatbike. Even though Bob’s the most un-tech person I know I didn’t post any build shots of the bike until he received it (unless you check out my Flickr).  I’ve known and ridden with Bob for over a decade. Bob was one of the first of the ‘elderly class’ that kicked my ass when just starting out racing in Colorado.  I remember thinking, “who is that old guy on the Moots killing it!?” Well, whether in Cross or MTB racing he’s been out there hammering and all the time with a huge grin across his face.  One of the nicest guys I know so I’m really psyched to perpetuate more smiles with a fatbike.  They just are so fun to ride.

This version has lots of standover for when he inevitably dismounts on soft snow and his feet sink in.  It’s running SRAM XX 2×10, SRAM X9 cranks, Fatback 170/135 hubset with Rolling Darryl rims and a Nate on back, Bud on front. The geometry is slightly slacker than what’s available in stock bikes with 69.5 / 72.5 head tube / seat tube angles.  The fork is 450mm axle to crown with 50mm of offset giving the bike 89mm of trail.  With a low (for snow) BB height (12.6″ un-sagged – tire pressure sag that is…) it should hug the ground pretty well.  The chainstay length i kept ‘normal’ at 447mm just to stay safe with tire clearance from the chain in the lowest gear.  Now with the new Surly O.D Crankset it probably would’ve been possible to go with whatever chainstay length but I’m not yet convinced that short chainstays are the way to go on a bike that’s mostly going to be ridden on snow.  If anyone cares to comment to stress another viewpoint, please do as I’d love to hear other perspectives.  I’ve had an interesting conversation with Mikesee (lacemine29.com) who built the wheels for this bike and he’s convinced an “all mountain” type geometry is the way to go for fatbikes — short stays and slack head tube angle.   He does have more experience than most anyone so I’m going to try it out on my next fatbike frame.  Winter is coming…

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