If you're chasing around for an Olympic bar, you may hear people talk about bushes / bushings and bearings / linear bearings / needle bearings and wonder what they're talking about.
In short, barbells with bearings have a smooth rotation so are better for olympic style lifts – they're also more expensive. Barbells with bushings are cheaper, but have poorer rotation, which make them suitable for lower weights and most home gyms.
A little more detail
Bushes and bearings refer to the mechanism on which the ends of the bar spins. Huh? So for a 20kg bar, we create a 7ft bar at 28mm-32mm diameter. We create an outer steel sleeve that is slipped onto each end of the bar and either bolted on to the bar, or clipped on. The outer sleeve then spins around the inner sleeve creating a rotating end.
Left with just an outer sleeve and inner sleeve, the spin will be very poor, and the components will wear out very quickly as you have the outer steel sleeve rubbing directly on the inner bar creating too much friction. This is where the bushes and bearings come in - they sit between the bar and the sleeve, allowing the sleeve to spin more freely around the bar, reducing friction and wear.
Bushings tend to be brass, or bronze (the latter being a better quality as it self lubricated). Below are some examples of bushings. Put simply, they fit between the bar and the sleeve either at just the inner edge, or inner and outer edges of the sleeves, reducing friction between the outer and inner sleeve, making the spinning movement smoother.
In barbells, bearings come in three types - ball bearing, thrust bearing and needle bearings. Like bushings, they fit between the bar and the sleeve and reduce the friction between the outer and inner sleeve, making the spinning movement smoother.
Of the three, ball bearings tend to be the cheapest, followed by thrust bearings and needle bearings. As a general rule, the more bearings in a barbell, the smoother the spin. (Note that this is not always the case - 10 cheaper bearings can often spin worse than one decent pair of bearings - you get what you pay for).
Needle bearing bars tend to combine bearings with bushings, while linear bearing and ball bearing bars tend to exclude bushings. See examples of a needle bearing cage, and the inside of a 10 needle bearing, 2 bushing bar below.
Above: 20kg PRO Olympic Barbell Hard Chrome (Bearing based bar)
So which is better? There are arguments both ways. Barbells with bearings tend to have a smooth rotation, so are better for Olympic style lifts, but generally will cost more.
Barbells with bushings are cheaper, you won't get quite as nice spin (or friction free movement) on a bushing only bar but they are fine for lower weights and most home gyms. They are also great for powerlifting where spin is not as important. It's also important to keep in mind that good quality bushings can provide better movement than poor quality bearings.
My two cents? If you've got the cash - go the bearings. The smoother movement is a lot nicer to play with and if you're planning on doing a lot of olympic lifts (things like snatch, clean), you'll appreciate the smoother movement of a bearing bar. BUT - if you go the bushing bar and spend the extra cash on plates, you'll love the bushing bar and never know the difference.
At the end of the day, Olympic bars are awesome and we offer bars with bushings only, bearings only, and both to suit all needs.