Friction is a problem on a skateboard where the wheels meet the ground, as high friction can slow down the skateboard and make it harder to maintain speed. This can be caused by debris on the ground, worn-out or dirty wheels, or a rough riding surface. Lubricating the bearings and keeping the wheels clean can help reduce friction.
when it is worn down to the point where the metal grinds the road
You really never wear in your skateboard but you get used to it. Your bearings will start spinning faster when broken in, Your trucks won't turn by themselves when worn in, and your shoes will feel comfortable and unstiff
well-worn, about $2 lightly-worn, about $10 uncirculated, about $75
Numismedia lists the following approximate retail values as of 05/2009: Very worn condition - 8¢ Moderately worn - 32¢ Slightly worn - 65¢ Almost no wear - $1.00 Uncirculated - $3.25+
well-worn = $1 lightly worn = $5 uncirculated = $20
Un-circulated probably quite a bit. In circulation and worn with age it is worth a penny.
A circulated penny may appear worn or dull due to being handled frequently. It may have scratches, discoloration, or slight fading of the design. The edges of the penny might also be slightly rounded or dented.
Shock absorbers are worn, wheels/tires need balancing.
A 1883 Indian Head penny would be worth $3 if worn, $16 if none circulated.
Look for any obvious signs of damage such as bulges or cracks. Next test the tread using a penny. Place a penny head down in the tread. If you can still see part of Lincoln'shead, the tire is worn.
penny hardaway and Steve francis