I am contemplating getting a trailer for my QNT.
...
The standard hitch will work fine.
While coasting, if I remove my hands from the handlebars,
the wheels shake violently
. recommended checking the tightness of the axles
and that the brakes are not rubbing?
chip@recumbenttrikestore.com:
One or both headsets are loose
and/or the toe-in is not set properly.
. it seems worse when the trike is on big apples ?
Wider/narrower tyre will move the centre of the contact patch laterally
(making the steering more/less susceptible to bump inputs),
might also affect brake steer sensitivity?
8.14: co.trike/trice/shimmy:
On Sun, Jun 14, 2009 at 8:52 PM, dthompsoncpa wrote:
While coasting, if I remove my hands from the handlebars,
the wheels shake violently.
my reply:
. I just got through reading
Bicycling magazine's Complete Guide to Bicycle Maintenance & Repair
and it said a common reason for shimmy at high speed
is when the rider weighs a lot on an ultra light or specialized frame .
. the trice makers warn of strict weight limits .
. that reason seems more likely on a bike than a trike;
but, I thought I should throw the group even remote clues .
8.15:
date Fri, Aug 14, 2009 at 2:48 PM
. I recently dialed out a wheel shimmy
with a 1/2" tweak of the rear boom length.
date Fri, Aug 14, 2009 at 5:09 PM
. Check your tyre pressures,
too low will cause some shimmy.
date Sat, Aug 15, 2009 at 9:35 AM
Hi, most times I've had shimmy is due to
the headsets on each wheel coming loose.
This happens quite often when new.
If you can get hold of some old school steel locking washers
with a corrugated under surface,
these seem to hold better than the thin alloy ones.
I also locked the threads with Loctite 243.
After a year I also found that the big nuts holding the front wheels
had become loose.
The front tyres should always have the same pressure of air in them.
Check all these things,
trikes cause a lot of vibrations to all moveable parts .
date Sat, Aug 15, 2009 at 10:06 AM.
. the shimmy on his 20" Q is now cured.
there was an o ring missing in the headset.
It might be worth checking your headset against an exploded drawing?
8.16:
. same problem developed on my new QNT after only a few days.
I tried to checked the alignment,
retorque everything I could think of,
and checking tire pressure.
It improved a lot but
there is still a bit of shimmy at high speed.
So I find that headset thing interesting.
The manual says:
"After the first 50 or 100 miles,
check the steering components for signs of looseness.
The headset bearings may need to be snugged up
after they have bedded in,
and the axles should be checked for tightness as well".
date Mon, Aug 17, 2009 at 7:35 AM
. ICE has been shipping (the last three trikes)
with a well greased O ring between the steering pin cap and first bearing.
.. for those who would like to try
adding damping to the steering,
one could insert--stretch and snap like a rubber band--
an O ring in this location.
The supplied ring has 1/8" thickness and 7/8" id with 1 1/8" od.
It is greased when installed.
The effect is a pressure fit between the cap and stem
which gives the steering some resistance.
date Tue, Aug 18, 2009 at 1:36 PM
. official word [on] the purpose for the O ring:
It was introduced to offset any excess steering vibration
--it is intended as a dampener.
Chip, recumbenttrikestore.com
8.18:
Phil Mix date Mon, Aug 17, 2009 at 8:10 PM
Joe, During my 7,000 miles on my Q
I didn't remove both hands at any speed above 10 mph
that I can remember.
However, I know that in breaking the two frames in,
at about 400-800 miles
the steering and tracking changed and the fix was:
tightening the loose headsets.
I am tempted to loosen the headsets as see if I can create this shimmy.
What is missing here is a root cause analysis.
Are the o-rings placed to
lessen the inevitible initial set in of the headsets?
The same retightening of the main steering bolt
was experienced in both frames.
I observed both times that removing the bolt revealed
a crushed ring of frame paint under the lower bearing,
when the crushed ring of paint was removed
and the bolt retightened,
eliminated the need for further retightening.
I have since been on some really rough macadum
and the steering is solid.
After the onetime tightening, retightening was not required.
[ shows a trice rider can steer no-handed
by leaning into desired direction .
]
Ha Ha ..no shimmy then.....2 years ago...
Phil
8.20:
date Wed, Aug 19, 2009 at 8:07 PM
Shimmy of this sort was once a very common problem in automobiles
of the 1920s and 1930s when most cars had solid front axles.
The axle would oscillate whenever its equilibrium was disturbed.
The addition of front brakes in the late 20s made it worse
by increasing the amount of weight on the ends of the axle.
It was the main reason for the widespread adoption of
independent front suspension during the 1930s.
My Model A Fords would develop it when their front radius rod attachments
(which kept the front axle in position) became loose.
It would happen much as described on a Trice,
when the front wheels would hit a bump simultaneously
(such as a ridge across the road) when going fast enough;
it would stop if I hit the brakes
and slowed down below the critical speed.
It is also endemic on Morgan cars,
which have independent front suspension,
but very hard springs
and practically no suspension travel.
I have previously remarked on the resemblance between
a recumbent tadpole trike
and a Morgan three-wheeler.
The crosshead of a Morgan behaves very similarly
to the cross-arm of a trike,
which similarly pivots around
its attachment at the centre
and relies mainly on frame flex for suspension.
On a Morgan, the frame flex absorbs more bumps
than the springs do (I can lean my full weight
on the front of my Morgan without compressing the springs).
On my 1970 four-wheeled Morgan
(which has the same suspension as the three-wheeler),
it happens right around 55 mph if it is going to happen at all.
The cure for shimmy on Morgans
is the same as on a Trice:
first make sure than everything is
tight and properly adjusted
(a 5 psi difference between front tire pressures
can cause Morgan shimmy,
as can wheel balance, kingpin wear,
and apparently the phase of the moon
) and then
introduce some friction into the system to dampen it.
My 1927 Morgan Aero has on it
a "Hooley Steering Damper"
that simply acts like the O-ring in a Trice headset.
In addition, as mentioned,
the rear end adjustment
(tire pressure, and boom length on a Trice)
can affect the front's tendency to shimmy.
Don
http://orangbasikal.blogspot.com
8.23: try the o-ring. [reinstalling what Chip uninstalls]
rgammelg@gmail.com
date Sun, Aug 23, 2009 at 9:09 AM
I started experiencing some changes in the steering
after about 300 miles of riding.
I checked the tire pressure and alignment.
Then I tightened the headsets and noticed a slight improvement.
I emailed Chip and he suggested that I
try the o-ring. [reinstalling what Chip uninstalls]
I just inserted it yesterday
and did notice some differences.
Even with proper tire inflation
my wheels would start to oscillate back and forth
and continue to exaggerate
until I had to put my hands on the steering.
Now, with the o-ring inserted,
I am able to ride with no hands and any speed.
Prior to the o-ring,
I would occasionally notice a slight pedal steer effect.
Now that also appears to have been dampened.
It was fairly easy to install.
Just loosen the two bolts on the side of the stem
(where the handlebars pivot)
and lower the stem.
Grease and apply the o-ring over the bolt
and above the top bearing.
Pull up on the stem until it is back in the original position
and tighten the stem.
Bob
