Thread: Wheel balancing

Hello All,

I'm finally assembling my resto mod after paint this summer and noticed that the rear tire seems out of balance. I installed new street sneakers (Perelli's) on refinished stock rims and slid the axle thru without the brake hub to take a look and found that it had a heavy spot close to the valve stem. It rolled pretty slowly so I dont think it was bad but I figured I'd ask to be sure. I have an 88 motor so it should get up to 50ish if that matters.

A: should I pay this any mind?
B: if so then what balance options are there that wont look like crap?

Thanks for the help. John

At these speeds with this type of rim & tire, I would'nt worry about balancing.

I don't know that it's even possible to have enough weight imbalance alone to cause noticeable tire shake. In my experience, there's always been a huge amount of runout accompanying it. Below ~45mph, it's a non-issue unless something is seriously out-of-round.

As for balancing options, dynamic balancing equipment that can accomodate a 10" doesn't exist, at least for practical purposes. A kart racing shop might be able to supply a bubble-balancer that will work. A cone-type lawnmower blade balancing device, if you can find one, would be a lot cheaper. A 5-10 gram self-adhesive weight shouldn't be highly visible. If more than about 15 grams is required, you've got more serious issues to correct than simple weight distribution. In more practical terms, as long as the wheel assembly is reasonably round (less than .125" runout at the tire tread), balance should good enough for the speeds you're expecting. In fact, even for a serious road bike capable of 50mph+ all day cruising, the only practical means of getting balanced wheel & tire assemblies is to start out with straight rims & hubs. From there, Dynabeads are cheaper and simpler.

You might want to see if your wheel imbalance remains with the tube removed. If it vanishes, question answered. Valve stem mass, alone, isn't enough to cause wheel vibration below 50mph.

Originally Posted by racerx

I don't know that it's even possible to have enough weight imbalance alone to cause noticeable tire shake. In my experience, there's always been a huge amount of runout accompanying it. Below ~45mph, it's a non-issue unless something is seriously out-of-round.

As for balancing options, dynamic balancing equipment that can accomodate a 10" doesn't exist, at least for practical purposes. A kart racing shop might be able to supply a bubble-balancer that will work. A cone-type lawnmower blade balancing device, if you can find one, would be a lot cheaper. A 5-10 gram self-adhesive weight shouldn't be highly visible. If more than about 15 grams is required, you've got more serious issues to correct than simple weight distribution. In more practical terms, as long as the wheel assembly is reasonably round (less than .125" runout at the tire tread), balance should good enough for the speeds you're expecting. In fact, even for a serious road bike capable of 50mph+ all day cruising, the only practical means of getting balanced wheel & tire assemblies is to start out with straight rims & hubs. From there, Dynabeads are cheaper and simpler.

You might want to see if your wheel imbalance remains with the tube removed. If it vanishes, question answered. Valve stem mass, alone, isn't enough to cause wheel vibration below 50mph.

Let me give you some examples:

The three bikes I will talk about here are setup for street with street tires and all running tubes.

1. 1971 CT70 running 120/90-10 on stock rims with a GPX177V2 motor. This tops out at 85mph. These tires were inflated and deflated and inflated until I was completely satisfied with the seating. I then took them to be balanced, which they didn't require any. This bike is smooth as glass at 85mph with no wobble.

2. 1974 CT70 running 100/90-12 F and 120/70-12 rear with a taky 124+r. These rims are spoked chinese motard wheels 2.5x12 f/r. This bike tops out at 79mph. I have not had these balanced, but did the same thing...inflate, deflate, inflate until I was satisfied with the seating. No wobble

3. 2008 Pitster Pro running 100/90-12 F and 120/80-12 rear with GPX170V2. Same rims as on the 1974 CT70 and bike tops out at 82mph. This one has wobble...but only when I reach up around 50mph and it is not because the tire is not properly seated, but that the front rim is slightly bent. It needs to be trued.

If you are experiencing wobble at 45-50mph, your tires must be poorly seated or your rims bent or your suspension is way too soft (or any combination of the three). Better fix that wobble and be safe...

Thanks for the info. I didnt think it would be an issue but I felt it best to ask. You guys are the core of this web site and I appreciate the passion in which you assist others and promote these great little bikes. Be safe and come on spring! John