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I recently bought two sets of these (8 per set) to replace the bearings in my old rollerblades as I felt the old ones were worn out. This was with the full intention of using the rollerblades regularly and trying to get a little bit fitter. Unfortunatley The plan to use the rollerblades regularly didn't really ocme to fruition but despite this the couple of times I have used them have shown the bearings to be excellent.
The bearings are ABEC 5 bearings. Although this standard is generally suited to bearings for machines ( a bit of my inner engineer coming out now) it gives a view of the precision they are manufactured too. Skate/roller blade bearings generally come in the range of ABEC 3 to ABEC 9, but the higher the value the higher the cost. Generally above ABEC 5 I have never found a noticable difference. The bearings are manufactured in China which tends to be where most small items are manufactured nowadays (sure it used to be taiwan)
The bearings are deep groove roller ball bearings which internally consist of stainless steel balls which run around an internal and external groove it the inner an outer bearing rings.
A nylon cover is fitted between the bearing rings which helps to contain the lubricant which is placed around the balls to help them run smoother and offer less resistance to movement. The lubricant used is called 'speed cream' by bones, so I have no idea what that actually is but it seems to work well and the bearings don;t show any considerable heat build up after use.
The nylon cover also gives some protection against contaminants (dirt and grit) getting into the bearings and wearing the internal parts. The cover is not 100% waterproof, so if using rollerblades (or skateboards) in the wet it is likley that water will get in and the bearings will deteriorate eventually. Note that for fully sealed bearings the cost would be much much higher.
I believe my old bearings were cheap ABEC 3s and compared with these Bones reds they were far inferior. I find I can whizz along at a much higher speed and the wheels turn much more smoothly.
I paid £15 per pack for these from amazon (£30 for 8 roller blade wheels - 2 bearings per wheel) which I consider quite reasonable for good quality bearings.
These really did improve my rollerblades a lot and I would highly recommend them from that point of view. I'd strongly suggest that it is not worth paying more for higher grades of bearings as there is little noticeable difference in reality, they are more precise but despite marketing the higher precision isn;t needed for skating applications.
I have skated my pair of bone reds since I started skating 3 years ago, and have never had to replace them. They are great bearing, even though they don't technically have an ABEC rating. They are very smooth, reliable and very long lasting. They also are very good runners and will allow the wheel to spin quickly for a long time and offer very little resistance. They are also extremely hard wearing as I have never broken a pair, even though I've skated high ledges and stair sets, and some my friends have broken there ABEC 5 bearings from just doing ollies and pop shovit's on flat ground.
When I brought them, I paid £15.99 for a full set of 8, the bearing are sealed with a rubber cover that is removable, but increases the chance of the bearing popping out, or grit getting into them, but does mean that any dirt getting in will come out quite quickly. On all of my bearings I did remove all of the rubber covers a while ago, and they still work perfectly well. I have oiled them once or twice, but there is very little need to do, unless you haven't skated for a while.
I have skated on other bearings, but I find that my bone reds are the best I've ever had, and me and almost everyone I know who skates uses bone reds simply because of their high quality, cheapness and the fact they last for ages.
They are also very easy to get in and out of the wheel and fit very tightly, and cleaning them is also very quick and simple if you use a regular skateboard bearing lubricant. But 3 in one oil also does a very good job too, but I would advise not using WD40 because it evaporates very quickly and can remove the oil layer there before and make the bearings rust quickly.
Just in case you don't already know , skateboard bearings go inside the wheel. The left the wheel freely move on the trucks with minimal friction so that you can get the most speed possible. The bearing are the most complex part of the skateboard with many little features. They also have to be extremaly strong to withstand landings as most of the force goes in to the bearing from the wheels.
Bones are the leaders in bearing manufacture. They are used by nearly all professional skateboarders because of there speed and un rivaled long life. Bones Reds are the cheapest of all the bones bearings but they are still the best bearings under £30 and they cost just £15. Bargain!
The bearings were quite easy to get into the wheels and easy to take out as well. They are also extremaly easy to clean. You simply pop the red case off and clean. You can also buy bones speed cream. This is just a lubricant that you can put onto the bearings to make them go faster and smoother. I would definatley recommend this!
Overall, the best bearings under £30. Last a extremaly long time, look great and come at a reasonable price. They are also easy to clean and easy to make faster. A great Buy!!