UNDERSTANDING DELTA TRIKE WHEELS
After having my trike wheels custom built the
spokes started working loose every few weeks because the shop copied the light
duty wheel’s offset dish pattern that came with the trike. A much steeper angle
on the disc brake side, like a bike's front disc brake wheel.
There is a theory that says that the spokes on the
disc brake side of a bike wheel needs to be shorter because the brakes will
pull the spokes on that side first, yet hubs do not twist. The only reason that
the spokes need to be shorter on that side is to make it fit in the wheel well.
Some people think that front wheel spoke tension
should be less than the rear because they think the high tension will collapse
the wheel. Yet the rear wheel of a bike is always asymmetrical making it much
less stable when it is subjected to high torque..... One side is inherently
tighter, so of course it will collapse.
JOBST BRANDT (The Bicycle Wheel):
The only reason that any bike wheel is built lopsided is to make it easier to
build a frame that will hold both wheels in alignment with each other. In
effect a lop sided wheel (asymmetrically dished) is only half as strong as one
with all the spokes the same length. (pages 32 & 39
PIPPA GARNER (builder of quadrocycles): Well,
yeah. I retightened the spokes on my canted wheels twice and finally got rid of
the pinging noises, but I had the problem on 2 different cycles with canted wheels,
one built by Varna in Canada, so the spokes must be tighter than what is
considered conventional in wheel building. Certainly the application has
something to do with it. There's no question that asymmetrically tensioned
spokes are subject to more stress than wheels with the rims centered between
the flanges.
HASE DELTA TRIKES: *yes, all spokes have the same
length (172 mm) and so they also have the same tension. A symmetric bike wheel
is the strongest solution, even with disc brakes. Both flanges on our wheels
are the same size. The Ez3-usx is a cheap copy of our trike. Best regards
Rüdiger Knopp Diese, hase-bikes.com
LIGHT FOOTCYCLES: Smaller wheels are much stronger
in almost all respects, mostly lateral stiffness. They would suffer less
distortion from braking, as well, because of the steeper angulations and
shorter spokes with less give. Rod Miner Lightfoot Cycles Inc. 179 Leavens
Road, Darby, MT 59829 USA , lightfootcycles.com
GERD SHRANER (the art of wheel building): for
years I worked with out a tensiometer, being under the false impression that
instinct and experience were enough. When I finally started using one I
discovered that even my mood on any given day gave me different result. To
adjust your rim off center on the axle, just visually determine the spoke
length. Then open the rim calipers on the truing stand and let only one side
touch the rim. You may need some new nipples because they could disintegrate
during adjustment. The tension for 14guage stainless steel spokes can be much higher
than for the usual 15guage aluminum. High tension can collapse a wheel if made
with cheap rims. BFR's are the best for lateral forces, but deep V rims are the
best for high torque.
BROX QUADROCYCLES: On wheels with low spoke
tension on one side you may experience the disc brake pulling the tight spokes
before the loose side. Centering the rim between the flanges will eliminate
this action, but you still need higher tension on the spokes because of the
compression factor from lateral forces. We use symmetrically dished wheels with
disc brakes, and box wall rims. Brox.co.uk
GREEN SPEED TRIKES: We generally build our rear
wheels symmetrically about the flanges (i.e. spokes the same length on both
sides) to take the extra side loading trikes put on the wheels.
KEITH BONTAGER (bicycle engineer) The disc brake
side spokes should be slightly looser, yet still have the same length. However
for light duty use a 20” wheel can be the same tension as the other side.
BOB BRYANT (RCN magazine): In a hard turn most of
the weight goes to the outside spokes so they should be at least as tight as
the inside spokes, because after all the axle does stand on the spokes. The
reason that Sun bicycles built the wheels like bike wheels is simply that they
couldn’t afford to build a new wheel-building machine and still keep the price
down.
