In this episode, Calvin and Truman crack open a cold one and dig into wheel imbalance and whether the finicky process of balancing your wheels makes a difference to overall wattage.
Tech Talks Presented by Park Tool is a monthly video series hosted by Park Tool's own wrench whisperer, Calvin Jones. The series covers the A to Zs of some of the most prevalent repair jobs, with the last highlighting how to bed in brakes.
Stay tuned for more mechanical how-to videos with Calvin returning on the last Thursday of every month to show you the easiest way to get the job done. Want to know more? Park Tool's how-to section has you and your bike covered.
I'm so behind the times. Just started using sealant, now people are already next level using beer instead. I get it though. Just ride and your tires inflate themselves. Any soda pop should do I guess. Next time I'm on the podium, I'm not just going to spray that champagne. Instead, I'll dump it in my tires.
As soon as you put the tire on, knowing that the wheel was previously balanced why not find the new heavy spot from the tire, mark it, and re-align it with the largest weight stuck to the rim, remove the weights and then re-balance the assembly. This would reduce the total added weight necessary to balance the wheel tire assembly.
Ignore the sealant, because the distribution of that liquid mass cannot be controlled. Assuming the wheel and tire is balanced and the "womp womp" is at a minimum, the sealant shouldn't pool up in any one spot too much.
Another thought, if there IS a heavy spot causing one spot of the tire to have a larger effective radius when the wheel is spinning due to the axle wobbling in sync with the heavy spot, wouldn't the liquid sealant want to pool in that spot due to centrifugal force, thus making the imbalance even more extreme?
All this said, I do not take the time to balance my wheels, because... ain't nobody got time for that.
Close.. You would actually put the heavy spot in the tire 180 from the heavy spot in wheel to oppose and then rebalance. It is called force matching. With all that said though, you have to be going over ~40 mph for a first order imbalance to appear. If you have a "womp" below that speed, you have a bent wheel or a tire not seated in the bead.
i tried to balance both alloy and carbon rims. Alloy weight is more evenly distributed and easy to balance. Carbon rims are more inconsistent and hard to reach perfect balance. This could be helpful when you ride at very high speed like pros. But for most mortals like us, balance in life outweighs the balance on wheels!
Does anyone remember the previous video where Calvin poured out a beer that was offered to him because he can't work "impaired?" It seems like they're desperately trying to make up for that embarrassing moment. Also, this video is basically unwatchable... just try to true your wheels adequately and then go ride. Worrying about wheel balance is for people who care more about gear than riding.
For normal mountain bike tires there is too many variables and the speeds are too low. For DH pro's it would be worth doing, but would have to redo it for each tire before adding sealant. Now on the road there is a big difference, especially at high speeds. I have been balancing my wheel/tires system on road bikes for 10+ years and at speed it is very noticeable. You can't just balance the wheel without the tire mounted. Even if you remove the tire you need to remount it the exact same or it will mess up the balance. I use a main weight inside the rim to get the initial balance and then lead solder wrapped around a spoke to fine tune.
I was waiting for the part at the end when they got to the tire and sealant, womp womp. No, I've never heard of anyone balancing a bicycle wheel and tire. Thought about it though cause it seems like good idea. But not going any faster than 35 mph, I'm not too worried about it.
In theory unless your sealant is dried up (which then needs removing and replacing anyway) the centripetal forces created by spinning the wheel will cause the sealant to self level, and therefore self balance, against the inside of the tyre. I would definitely balance with the tyre and valve fitted though, the same as you would with a car wheel/tyre.
I have to wonder if even a very very slight off-centeredness of the hub could place a pretty significant amount of mass into the wrong place - so maybe the answer to this is in a very careful tuning of the spokes, maintaining even tension but shifting the center of the axle in the right direction. On a more important note, though - is it Pigsty or Landfill you guys are drinking?
I guess that a good mechanic could achieve that in a reasonable time on a new rim. But as soon as I get some (mtb) mileage on my rims, I get some slight bends and I usually use slightly uneven spoke tension to get the rim true again.
So I'd have to deal with spoke tension, wheel trueness, bends and hub centering. I already have a headache!!
@t1000: haha one time I helped a customer build a set of wheels with hubs literally 5'' off center, so that he could pump his full size scooter along on the flats. Each spoke was a different length! Now that was a headache, but he built the wheels himself, thank god.
Makes sense to do some type of balancing , especially on the larger tired wheel sets. I know I can feel the out of balance wheels on the trail at times and at certain trail speeds. Being a machinist I have seen first hand the effects of balancing and not balancing.
Pretty much the same procedure and tools the tire guys in the pits run through after putting a fresh set of rubber on your roadracing motorcycle wheels -- except they get the job done a lot quicker than these guys. Some of the racing tire manufacturers are nice enough to put a mark on at the heaviest point so you can orient it across from the valve. Don't think it's worth the bother for the comparatively low speeds in cycling though. At least most of the valve stems nowadays are Presta type, so the tire can't go flat at high speeds due to centrifugal force overcoming the spring force in a Schrader valve
I tried this some time ago and my rear wheel is perfectly balanced as is. The front was harder but I just rotated the tire on the rim to find the balance point. No need to add weights as I'll get mud on the tire anyway. It's one of those things that makes sense to some degree, but you shouldn't push it too far.
I like fishing led weights idea. I would consider putting some opposite of the valve, but that's as far as I would go for balancing. I wish there was better QC for tires. I hate how they are never straight and can only imagine how uneven the weight distribution is on those.
Great vid! If there would be an easy way to do it with some sort of measurement-device and handy tools, and have e.g have different weighing spoke-nipples/-nuts for the jobs, I maybe would try one day, but until then: nä
I used to put a tennis ball in my spokes, closer to the hub rather than weights closer to rim to balance my wheels. Felt great getting rid of the wamp wamp wamp on cheap wheels.
Think of it like a donut on a bat - it's nice to warm up on but you don't want to hit the bat with that puppy! Take the donut off and you can ride away!
Not sure how you'd balance it once the sealant is in there, anyways. The minute the wheel slowed down enough to take a reading, the sealant would pool at the bottom.
Ignore the sealant, because the distribution of that liquid mass cannot be controlled. Assuming the wheel and tire is balanced and the "womp womp" is at a minimum, the sealant shouldn't pool up in any one spot too much.
Another thought, if there IS a heavy spot causing one spot of the tire to have a larger effective radius when the wheel is spinning due to the axle wobbling in sync with the heavy spot, wouldn't the liquid sealant want to pool in that spot due to centrifugal force, thus making the imbalance even more extreme?
All this said, I do not take the time to balance my wheels, because... ain't nobody got time for that.
Mind blown
Now on the road there is a big difference, especially at high speeds. I have been balancing my wheel/tires system on road bikes for 10+ years and at speed it is very noticeable. You can't just balance the wheel without the tire mounted. Even if you remove the tire you need to remount it the exact same or it will mess up the balance. I use a main weight inside the rim to get the initial balance and then lead solder wrapped around a spoke to fine tune.
I would definitely balance with the tyre and valve fitted though, the same as you would with a car wheel/tyre.
So I'd have to deal with spoke tension, wheel trueness, bends and hub centering. I already have a headache!!
Centripetal = force from outside to center
I've had Gluten free beer (meh, Ghostfish, meh) but that looks like soda to me....