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Yeah, high RPM probably doesn't mean much at all... Things to look for would be ABEC ratings(tolerances of the two races, how close they fit, how much play there is) or just price, honestly... I hate to say it, but a lot of the really cheap ball bearings can be for conveyor belts and things and are not at all what you want to use for this event. I'd be leery if they don't offer too much details on them...

The bearings I'm looking at are these: http://www.amazon.com/gp/product/B00634 ... PDKIKX0DER

Do you have any experience with these or see anything that would be indicative of good or bad?

catfoot wrote:The bearings I'm looking at are these: http://www.amazon.com/gp/product/B00634 ... PDKIKX0DER

Do you have any experience with these or see anything that would be indicative of good or bad?

Those are pretty cheap bearings, probably about the same quality you'd get if you removed bearings from a pair of roller blades or an old scooter. Personally, I'd recommend Bones bearings. The cheapest ones are around $15 for an 8-pack and they're easily good enough for this event.

http://www.amazon.com/Bones-1BEBOR-Reds ... s+bearings

Bones also makes higher quality bearings than this. Look at their website if you're interested.

JTMess wrote: Those are pretty cheap bearings, probably about the same quality you'd get if you removed bearings from a pair of roller blades or an old scooter. Personally, I'd recommend Bones bearings. The cheapest ones are around $15 for an 8-pack and they're easily good enough for this event.

http://www.amazon.com/Bones-1BEBOR-Reds ... s+bearings

Bones also makes higher quality bearings than this. Look at their website if you're interested.

Do you know what the ID of the bearings you linked are?

If you want to understand the factors that will get you to lower friction, Google "ball bearings friction"
Smaller diameter = lower rolling friction.
Especially with the ramp height scoring this year, every little bit of friction reduction pays off big-time.
The Bones skateboard bearings are 8mm i.d.; that's 0.31496 inches. That's a lot bigger than you need.
Also means some sort of sleeving to fit inch-sized axle (e.g. 1/4, 1/8th, etc.).
ABEC ratings do not reflect/correlate to rolling friction.
Also, shielded bearings, like this have slightly higher friction than open ones.
Lubrication actually also increases friction.
We're running 1/8th i.d/1/4 o.d., open- see discussion from last year.

Well thanks everyone for the ideas, but my partner has decided to completely redo the car and make it wider since we can't really do any thing else to change it to make it go straighter.

Balsa Man wrote:If you want to understand the factors that will get you to lower friction, Google "ball bearings friction"

We're running 1/8th i.d/1/4 o.d., open- see discussion from last year.

I would very much like to read that discussion. About what month did it start. There are 50+ pages with about 20 entries per page. Sure would be nice to have an idea of where to start.
Thanks

There is a search command. Search for ball bearings or something of the like and look for gravity vehicle enteries. Also gives you a look at others from other older events if some information is there

If you want the description balsaman posted last year concerning the vehicle that'd be here

http://www.scioly.org/phpBB3/viewtopic. ... ch#p203598

iwonder wrote:If you want the description balsaman posted last year concerning the vehicle that'd be here

http://www.scioly.org/phpBB3/viewtopic. ... ch#p203598

Did video of this car ever end up being posted?