Just got my replacement tires in. The rear one needs to be replaced soon after just 4000miles. Before I get started I need some advice. How does one balance the rear wheel? Since this wheel comes off the hub motor, you cannot use the usual axle mounted balancing approach for the rear wheel. You also have way too much resistance when mounted. Any tips?
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Your wheel may well have been balanced ON its gear hub at the factory, so be sure to mark the wheel and hub both so the wheel will be installed in exactly the same place on the hub.
Motorcycle tires usually come with a balance dot somewhere on the sidewall. Align the dot with the valve stem and you will most likely be done with balancing the tire. Very few bike tires need anything balancing beyond proper tire alignment.
Balancing is done at the factory with ONLY the wheel and tyre using an adapter plate for the Vectrix wheel to the balancing machine. Seeing that virtually nobody has the adapter plate, balancing in the field is not done. I have had numerous tyres fitted to V wheels and other vehicles and as Mocassin says alignining the dots on the tyre with the valve stem the balance is often very close to being spot on. I personally have ridden many bikes (too many to count!) after using this method and found none to be excessively out of balance tocause enough vibration to notice at speeds up to 130 mph(not on the V of course or on the road that I will admit to ;-). Just make sure you have the rotation arrow pointing in the correct direction, inflated correctly (32psi front 40psi rear) and remember to 'scrub' in your tyres for at least the first 10 to 20 miles as they are quite slippery for the first bit with the waxes used for mould release and can put you on the pavement. Oh, make sure to clean your rims around the bead seat to remove any junk from the old tyre and might as well clean up the rim itself to remove all the road crap that builds up which can affect ballance. Leave the original weights on then remove if you feel ecessive vibration coming through the bike and up your bum.
Doug Townley
info.DTES [at] gmail.com
(Formerly Vectrix Europe Technical Supervisor)
One door closes, another door opens
I had my time wondering about this one, had my rear tyre replaced about 800 miles ago. No balancing was required and there was no wobble.
I have had success with rear tires by elevating the rear wheel above ground, using a center stand or scissors jack, and putting the wheel in motion by engaging the motor, while watching it to see if it trys to vibrate up and down. (An unbalanced wheel will vibrate/shake noticably at speed, be careful that it does not contact pavement while testing!) If no vibration is noted, you are OK, but if vibration IS present, make a test installation of a small wheel weight, and retest. Depending on the result, you may need to move the weight, untill you find the best location-mark each spot tried, to speed the process, once the best spot has been found, increase or decrease the weight to find the best amount to use. This enables you to obtain good overall balance of all parts involved.-Bob
Robert M. Curry
Thanks for clarifying that. My rear wheel has a whole string of weights on it in one spot, and I couldn't imagine just a wheel and tire assembly only being THAT badly out of balance!!!
Well, I finally got around to changing the rear tire today and things went pretty smooth. Since I don't have a center stand (I guess few people do) I bought a Sears Craftsman motocycle jack for $159 on sale which worked flawless. Loosened all the screws and jacked the bike up. Once the swingarm was removed, removing the wheel was easy. I marked the hub and wheel so I could mount it back the way it was. Using a lever made from a 2 by 4, I was able to break the bead of the tire, and, with old-fashioned tire irons, was able to pry it off using rim protectors so as to not harm the rim. I did use some mounting compound that I got at AutoZone and I highly recommend that stuff ($12 for a 6lbs bucket which will last me a lifetime). Anyway, once the new Pirelli tire was in place, I mounted the wheel (using a torque wrench to make sure that all screws were to the required specs, 145Nm axel, 23Nm wheel nuts, 23Nm swingarm, 25Nm caliper bolts, 57Nm shock bolt) and was elated that in just about 90 minutes I did my first successful tire change on a Vectrix. True sense of accomplishment!
Next, while still on the jack, with the rear wheel off the ground but the front wheel touching and the handlebar centered, I started the bike and reved up the motor. The handlbar started shaking left and right and wobbling at around 25mph getting worse at 40 mph and then getting a little better at 55mph. Now I started taking the weights off the rim one at a time and things got a little better but still wobbly. Once they were all gone I started using two 7g weights and taped them to a random spot on the rim with clear packing tape. Little by little moved it in roughly 2 inch increments around the rim repeating the reving of them motor each time. Ultimately found a sweet spot where the wobble was the smallest. Added one extra 7g weight and bingo, the bike showed no wobble or jitter from 0-60mph on the stand. Took the backing off the weight and permanently attached the 3 * 7g weight at the very spot and the wheel was perfectly balanced.
Now I don't want to argue with the experts on this forum, certainly not with people who have done this a lot longer than I have but I would suggest that spending a few bucks on balancing weights and using the above procedure is not going to hurt and cost me an extra 20 minutes. I just rode the bike for 25miles and it rides smoother than ever.
Mind you, in the land of my fathers, Germany, all wheels are balance on the vehicle while spinning the whole drivetrain. Ideal way to do it as it balances not just the tire but the rim and hub too! Of course, they drive on the Autobahn at 130mph while we are supposed to top out at 70mph, on the Vectrix at 62mph. Anyway, I am pretty sure that a bit of balancing may be in order for the Vectrix.
I used a similar technique, but Blu-Tack instead of lead weights. Once the best weight and spot for it is found, I replace it with a lead weight. It's quicker and safer - imagine temporary lead weights coming off when the wheel spins at 100km/h....
This information may be used entirely at your own risk.
There is always a way if there is no other way!
One trick I've used with a different scooter is to lay a block of wood along side of the wheel, spin the wheel (find the wheel speed where the vibration is the worst), and then lightly touch a felt marker or crayon to the inside of the rim, using the block of wood to hold the marker steady. This will leave a scuff-mark on the "light" spot of the wheel's circumference, or because of inertia in the system, maybe 20 degrees "behind" the light spot. Put some trial weights about 20 degrees ahead of the mark, and redo. There is still some trial-and-error involved. I don't know if this will work, or can safely be done with a Vectrix.
Thanks for the writeup, Harry (and others). While many bikes can be reshod without need of balancing, my V's rear wheel has an unusually long string of weights on it, which does concern me with new tire time not too far in my future.