When I walk my bicycle, every few feet it stops like I've pulled the hand brake. It will roll some more then stop again. What do I need to do to fix it?
I'm assuming you have rim brakes.
Lift each wheel in turn off the ground and spin it. Does it appear to snake from side to side as it spins? If so, your wheel is out of true (it's no longer a disk but a sort of round Pringle) and it's catching against the brake pads at some part of its wobble.
If the wheels look OK when they're spinning, place the bike back on the ground and try to push the bike sideways by putting your foot against the axle. Does the wheel wobble against its mounting? If so, its bearings are bust.
Both of these are things that only an experienced bike mechanic would have the tools and skills to fix, so unless I've missed something, you're going to have to take it to a bike shop.
If it is an issue with the rim itself being misaligned this is something you could fix yourself if you feel confident. You need a tool called "Spoke key" or "Spoke wrench", which allows you to fasten, and unfasten the spokes. My city has a bike club (German ADFC) which offers a public workshop twice a week, where you could lend the tools (and get some advice). I did the same thing to my bike, and it was not too difficult. If you cannot lend, it costs about 10 Eur.
- By slowly turning the wheel and watching the distances between rim and brake heads, find the area of the rim that is misaligned and touching the brakes
- Put duct-tape markers where it starts, and where it ends
- Spokes connect to the rim on both sides. Each spoke has fasteners close to the rim.
- By fastening the spokes on either side you can force the rim to move slightly towards that side. Make sure to even out the force by fastening several nearby spokes, and also loosen the spokes on the other side just a little.
- When done, turn the wheel and let (for example) a screwdriver hit the spokes halfway between hub and rim with approximately constant force. The contacts should all emit a similiarly pitched tone: If a spike pings higher it is too fastened, if it pings lower it is too lose. Both are bad, because it increases the stress individual spokes have to bear.
- There is also a tool that allows to measure this more directly available if you can visit a workshop.
- Do not fasten the spokes too much, they are meant to have some headroom to move if the wheel bumps.
- Observe the distances beween rim and brake: The wheel should not wobble anymore. If there is still wobbling, repeat.
Unless the rim itself is damaged, this usually allows to correct the issue.
Disclaimer: Because it is really bad if your wheel breaks while you are riding, exercise caution after having done this repair. If you have any doubts about it, let an expert do it.