| The Bicycle Rack for Motorcycles |
Frequently Asked Questions:
1Q: I was thinking about a possible problem with the rack system last night - carbon fiber
frames. The rack grabs the downtube and I'm guessing puts quite a bit of stress laterally on
it. Since the majority of my bikes (and probably most people who buy your frames) are
carbon... Have you investigated what kind of force they can take from a small pressure point
on the downtube? I know other racks grab bikes on the downtube, but they are already
holding the rear wheel solid, so the downtube is more for stability (i think)…
1A: I do understand, it is an unorthodox method of carrying a bike, I know.
To get an idea of the load on your frame, lift your bike up by the down tube just in front of the
Bottom bracket. That is the load that your bike "feels". Your bike, of course, weighs less
than 40 lbs...i.e. it's not much load on the tube surprisingly. It looks scary, but it really isn't
that bad at all.
Because the holding point is so close to the center of gravity of the bike, this method of
holding the bike exerts less stress on the tubes than say a rack that actually uses a clamp to
hold the bike in place.
Let's look at it a different way, For starters, consider the area of the down tube that comes in
contact with the support pad; at its smallest it is about 5 square inches. If you conservatively
assume that the bicycle weighs 100 pounds...that's 20 PSI of pressure on the tube. Take it a
bit further and assume that all of the bike's weight is cantilevered out over the down tube
mounting point and hanging from the rear drop out. That would effectively double the weight
felt by the down tube to 200 lbs at the mounting point (because the mounting point is
approximately centered between the front wheel and rear drop-outs). That translates to 40
psi worth of pressure pushing on the down tube.
2Q: Doesn’t holding the bicycle by the downtube hurt the paint and the derailleur cables?
2A: The Johnny Rack comes with 2 mounting pads made of EPDM (the same material used
in car door seals). One pad slips under your cables and one is attached to the attachment
point. This protects your paint and isolates the cables to minimize damage to them and the
bicycle frame. Some minor abrasion to the paint on the bicycle may occur if the pads or
bicycle are mounted dirty.
3Q: What if I have a large downtube…how do I clamp it to the support?
3A: The Johnny Rack uses the Yakima BOA to secure the bicycle to the rack. The Fork Mount
is used in the traditional way, but the wheel mount is used to support the downtube of the
bicycle. The wheel mount strap is used to secure the downtube to the mount. The Strap will
only hold a downtube that is about 3 inches tall, anything larger than that requires the use of
a Velcro strap. (My Prototype Testers buddy used a Velcro strap on our 1200 mile tour
without a bit of problems because he lost the wheel strap.)
4Q: I have a Maverick with a tubular 20mm front axle…can I use the Johnny Rack?
4A: There is a solution for mounting the bicycle…Rocky Mounts does make an adapter for
the Fork Mount portion: http://www.rockymounts.com/maverickadapter They also make a
nice solution for the 20mm Thru Axle bikes: http://www.rockymounts.com/flytrapadapter . We
don’t have a solution for the wheel mount yet, but we anticipate working with Maverick to
come up with a solution. For now, we are using long Velcro straps to secure the wheel to the
bicycle.
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