tire balancing question...

[Super]

I've never seen this question asked before and it may be silly or obvious but.... I'm having new tires put on the project bike. Right now I have the wheels off the bike so I could do some cleaning on them. I have the brake rotor off the front rim and the sprocket off of the rear tire. My question is this... do I need to have the rotor and sprocket back on the rims when I have the new tires put on and have them balanced? Does having the rotor and sprocket off the rims at the time I have them balanced affect the balancing process?

Might be a stupid question but, in the past, I've always had the rotors and sprockets on when I've had new tires installed.

[Brendan W]

I' Does having the rotor and sprocket off the rims at the time I have them balanced affect the balancing process?

Yes. By how much, probably not a lot. Bike rotors are light-ish compared to cars which when new you'll often see balance nicks machined out of the disk.
Best practice to have the lot on the rims for balancing but I would be surprised to see the disks and sprocket throw the balance out unless you are headed to salt flats

[sharpy]

As a very experienced professional motorcycle tyre fitter for over 20 yrs never did we balance Sprockets and there carriers. Discs where always on the wheel but i cant see how they would effect bike handling. As for speed V Balance have a look at the MotoGp guys. There wheels are balanced bare and statically so if the Ducati can do 217 mph every lap and have no issue i cant see a GSX with top speed of 130 having problems. And i dont care who chimes in about balancing beads, thats just there opinion just like this is mine. Static balance, no beads and what ever parts are fitted at the time will be fine. If we had issues with customers coming back saying it was wobbling and it didnt do it before the new tyres there was ALWAYS something else on there bike like steering head bearings (90%) or something else wrong. FYI, it also recommended to change the tubes every 2 tyre changes as they do wear but that is being a little anal. Just a good inspection and comman sense be fine. Also lately ive been helping out at a motorcycle wheel rebuilding business and we balance wheels same as i always have done. Discs/no discs, steel/alloy rims, skinny/fat rims, 16-23in rims all dont matter. For those who say there is too much balance weight on the wheel and they have the dot on the tyre at the valve it is common knowledge that that dot goes at the heaviest part of the wheel, so who says its at the valve. Check the bare wheel for the heaviest area and mount the dot there. So move the tyre to suit and maybe trying flipping the tube over to make the wheel use less weight. And dont even think about using GS/GSX wheels or any wheels as tubeless unless the wheel has it stamped/cast as a tubeless wheel. That is just asking for trouble and one more thing that can go wrong on a vehicle that hugely fun but still can be deadly. FYI. All of this is just my opinion from a very long experienced life with bikes. If you dont agree, just do as you wish with your own bike.

[bwringer]

In my experience, any imbalance in cast motorcycle wheels comes from inconsistencies in the casting. And vintage motorcycle wheels are more likely to have greater imbalances than modern wheels, which makes sense -- modern manufacturing is more consistent. (Spoke wheels can have inconsistencies as well, of course, but assuming the wheel is reasonably round and straight, the tube is generally the "most inconsistent" part of the system -- rubber is not a precise material, and tubes usually have the heavy spots at the valve stem.)

Anyway, brake rotors and sprockets are made far more precisely and in a very different way than wheels, so they should have little to no imbalance. Sprocket carriers are cast, but are relatively lightweight and close to the center, so would have little effect on balance when assembled.

In other words, don't worry about it.

[Super]

Thanks from both of you guys! I especially like it when people with LOTS of experience chime in, as both of you have. I probably would have never wondered about balancing the wheels without the rotor and sprocket on until now. Thanks again.

[tkent02]

I have swapped rotors on motorcycle wheels dozens of times, never felt any change or misbalances in the wheels after.