I live in Canada (Ontario) too so will use Cdn prices
and all the parts are available from Toronto, to BC
and Montreal.
First, I use standard 20", 48 spoke BMX wheels with 14mm
axles that can be bought anywhere from about $15 wholesale
up to about $100. I don't know what the spoke tension is
because I buy the rims already assembled, and I've never had
a wheel fail, or heard of one of these wheels fail, on a
trike yet. I undo the wheel, jam and bearing nuts and shift
the axles over to one side as far as they can go. This is
usually in the range of having about
1.75" to 2" of axle sticking out past the bearing/jam nuts
on one side. To secure the axles to the bottom of the king
pins, I use plain old 3/4" ,ild steel tubing with 1/8"
thick wall. I cut a piece about 1.25" long and weld it
(both MIG and TIG) at the appropriate angle to the bottom
of the king pin bolt. I take a 35/64" drill bit (I don't
have a 14mm drill bit
) and drill out the center to
accept the 14mm axle. Just about a perfect fit. As for
strength and wheel security/tightness:
- my brother is 6'4" and weighs 265lbs. He rides my trikes
all the time and the wheels are fine
- a friend is 6'1", weighs 260lbs and he puts the trikes up
on two wheels and rides them around like that just about
daily. He says it's a "crowd pleaser"
- I am 6'2", weigh ~235lbs and ride fast and hard most of
the time. I have taken 90 degree road corners on narrow 2
lane roads at ~45kph - no problems at all. I also ride the
trikes around occasionally on 2 wheels, sometimes at
speeds approaching 30kph. Again, no problems.
- we all have ridden the trikes to relatively high speeds
(approaching 75kph) and our roads and sidewalks are not
always as smooth and crack/pothole free as they could be.
While I have to watch the wheel's axle nuts to make sure
they stay tight (I use red and blue Loctite), I have never
had an axle housing stretch/deform on me, I have never had
an axle bend or break. The 48 spoke 20s might flex
1/4" when riding hard corners or up on two wheels. They're
very tough it would seem. I never hear the spokes clicking
or pinging and I would think that those kinds of noises
would be evidence of rim deformation or wheel problems
(not an engineer - so don't quote me on that). The only
things I worry about are the 26" rear wheels. Again
though, they are standard steel and aluminum 36 spoke rims
that can be bought for around $35 and come already spoked
and ready to use once a freewheel/cassette has been spun
on. While people have commented on how much the rear wheel
flexes while up on two wheels or during hard cornering,
again, I have never had a failure and hear no spoke sounds
that I would associate with problems. I have a small magnet-
powered tail light that has the magnet mounted about 3/4"
away from the light housing. When cornering hard at speed,
the rear wheel definitely flexes enough for the magnet on
the spokes to come in contact with the housing. I tried a
27" wheel and it was definitely not strong enough for
trike use with the standard narrow hub. My friend and I
are going to machine some custom x-long 36h hubs and make
a couple "triple 27"" race trikes.
I don't know what your planned loading is going to be, but I
have build enough trikes like this and put enough KM on them
to have pretty much 100% confidence in the BMX wheels, the
standard plain-Jane 26" wheels (36 hole) and the mild steel
axle housings.
Hope this helps. Post pics when it's done
> I really must work on how I word things and be explicitly
> specific
>
> I am looking for a good guess (if not exact numbers) of
> the maximum side load a bike wheel (preferably a cheap 20"
> bmx wheel) can take before becoming a pretzel (i.e
> catastrophic failure and or but not including warping).
> This includes but is not limited to (ha-ha) nuts, washers,
> axel, axel bearings, bearing keepers, hub, spokes (likely
> 32 in total), spoke nipples (32 to match previous item),
> rim, rim rubber band to keep the nipples from the tube,
> tube (if used, if not strike last comments, preferably a
> standard tube not a shrader valve tube), and tire
> (preferably
a
> slick as it is a road bike). One more thing, I will be
> using 14mm and
above
> size axles before this deviates us from the current
> question leading us
into
> many many debates on stuff other than the question
> at hand.
>
> What I am trying to do here is design a frame (trike) and
> on the rear axel (two wheels on this axel, maybe a bad
> choice of words here again 'on the rear weldment
> assembly, which are attached 2 axels') figure out the
> necessary strength of the rear weldment assembly. These
> wheels (on the
rear
> weldment assembly) do not lean, they will be vertical at
> all times and should I hit a turn at a high rate of speed.
> I know approximately how many G's I generate on this said
> high rate of speed turn, I want to know how
much
> the wheel will take before warping. I then will take this
> data and build
the
> frame to take the side load the wheel can, using
> appropriate safety
factors.
>
> Before I get a lecture on the theories on design and that
> I may be over my head in this, I am a experienced aircraft
> designer and have FEA and CFD tools to help me in this
> venture as well as experience in doing the calcs
by
> hand.
>
> I am not trying to be smart here I just want to be
> specific so I can find out a resource of side loading
> capabilities of a bike wheel or how to calculate it
> without having to rig up a test and determine it my self.