Bicycle Mechanics - my cranks are possibly loose?

for reasons i dont know, when i peddle forward it goes loose for a bit then catches and peddles normally, when i stop and back pedal to skid it goes loose once again for a bit then catches and back pedals normally. there is a 'loose spot' so to say for about an 2 or 3 inches of space. i have no idea what the problem is, im ganna take it to the shop to see if it fixable. but has anyone expierenced this problem with their own bicycles?

Assume fixed gear? Don't have one but think it might depend on your bike's particular setup in terms of crank/hub/cog...

It's either peddle or pedal; can't be both unless you are selling pedals.
good luck on the problem.

i learned the bottum bracket was becoming more and more stipped.
i purchased a track wheel and its super heavy duty now, thanks alot.

i learned the bottum bracket was becoming more and more stipped.
i purchased a track wheel and its super heavy duty now, thanks alot.

?? Your bottom bracket was bad but you fixed it with a new wheel??

My assessment - the rear hub was stripped. Pedal forward and the cog rotates on the hub a bit before screwing tight. Skid and it goes the other way into the lockring. Repeat. Guy was wrong calling it the bottom bracket - the hub was the problem.

Unless he got a bottom bracket out of the deal as well. In which case, I have some bicycle clear-coat that he really needs to buy right after I fill his tubes with nitrogen.

Never know with the fixie kids.

lmao

I don't get that either? how did he go from a loose crank to a back wheel? I could never do that when I was in the business. well I tried but could never pass it off *blushing*. I guess the play was the COG and lockring?