Cmq

I am a college student and don’t know much about bikes. I rode my bike to the store and locked it up. When I tried to leave the back wheel wouldn’t spin and the pedals wouldn’t move forward. I called my stepdad and he said the chain probably moved off the wrong sprocket (I don’t know what any of this means) but I ended up moving the chain to the biggest sprocket of three by the pedal. Still wouldn’t go. What I’ve found is that the pedals won’t move forward while on the ground. The pedals can go backwards whether it’s off the ground or not. When I lift the bike off the ground by the seat, the pedals will go forward. I cannot post any photos since I am new to this page.

rseeker

If you want to get to ten posts so you can put up pictures, introduce yourself over in the Introductions subforum.

And welcome.

Sapperc

Sounds like your rear wheel is binding. Could be a number of things. Since you don’t know how to troubleshoot the problem you probably can’t fix it. Take it to a bike shop. Good luck.

CliffordK

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CliffordK

Ok, your chain looks very very dry, and badly needs some oil!!!

Can you upload some photos of the rear sprocket set of the bike from a couple of different directions? Also the rear derailleur. I'm seeing a bunch of slack in the chain in the third photo which I presume is from back pedalling, which indicates that the front chainrings are probably OK, and you likely have some issues in the rear.

Cmq

Will post some pictures tomorrow when I go back to get the bike. Also, my mom had the bike sitting in the shed for several years and only gave it to me last year. Unfortunately, I have not done any kind of maintenance on it

100bikes

If your bicycle has a rear QR, perhaps someone opened it and tried to remove the wheel and closed it with wheel in slightly different position.

_ForceD_

The OP says "When I lift the bike off the ground by the seat, the pedals will go forward."...so presumably the rear wheel is spinning (forward). So why wouldn't the same happend when the wheel is on the ground? Just wondering if it's spinning 'freely' or if it might be rubbing on a brake pad...AND in the highest gear...the combination of which might make it appear to be seize or otherwise unable to spin.

Dan

CliffordK

In general bikes are pretty simple. Two wheels that spin.

The middle of the wheels have hubs with bearings and grease, and attached to dropouts.

A chain connects the cranks and front chainrings to the sprockets at the rear (cassette/freewheel).

Anyway, if something isn't spinning right, it is often something rubbing wrong, a chain in the wrong place, etc. Just look for what is out of place or rubbing.

If your chain has been neglected, it is quite possible other bearings have been neglected.

That is a little harsh. But, it could be something where it would be useful to go to a bike co-op with someone willing to do some instruction. Or, find a neighbor or coworker that likes bikes and will give some advice & instruction.

Or, perhaps simply sit back and look at the bike as a puzzle with an answer.

Everyone has to start somewhere.

Hiro11

No offense, but you really can't figure this out? Look at the last picture you posted. Your chain has been "sucked" between the chainring (big gears on the front, the ones the pedals are attached to) and the frame of the bike. Just pull the chain out of there and you'll be good to go. This should take about 1.8975 seconds. Also, put some lube on that damned chain.

CliffordK

"Chain Suck" is usually at the bottom of the chainrings.

That last photo seems to show what happens when backpedaling.

Thus, the issue is something that is happening at the rear of the bike (and perhaps the user's description of the symptoms).

MikeyMK

The chain hasn't seen lube in so long that it's seizing in places. When the pedals are turned backwards, the chain is locked at the rear gears, and the chain is bunching around the crank. Likewise, even when the chain is back to form, sections of it are blocking the rear jockey wheels and preventing it from running smoothly.

Cure; coat the chain in oil/lube, and leave overnight. Be sure to ensure every link of the chain gets oil.

Watch a YouTube video of basic bicycle maintenance.

Wilfred Laurier

Nothing in those pictures looks so bad that I would expect the drivetrain to be seized up. I would thing the chain and wheel would turn with amybe a few tight spots int he chain, but it would be rideable.

The description of the problem that it seems to pedal forward with the rear wheel off the ground but not when a person sitting on it makes me think it might be a broken axle or frame - the weight of the rider or force in the chain that pulls the broken part out of alignment and the wheel jams, either the rim or tire against the frame, or the hub against he axle where it should be riding on the bearings.

2manybikes

The last photo clearly shows the chain off the front gears (chainrings). It is stuck between the frame and the crank (the part that the pedals attach to.) You might be able take it off yourself, If not find a bike shop, sometimes your need to take the crank off, and that requires a special tool.

Wilfred Laurier

That is a 'one piece' (Ashtabula) style crank. It is an outdated design generally only found on the least expensive modern bikes. The one advantage it has (besides low cost) is that is can be fully disassembled with no specialized tools - IIRC you only need a large adjustable wrench.

https://www.sheldonbrown.com/opc.html

Homebrew01

Yup, a little careful "tugging" should un-jam the chain. Although, some pictures show it correctly on the chainring.
Perhaps that "jammed" pic was from pedaling backwards ?

If off the chainring, place it back on the front ring, that matches the gear shift #
If the shifter is in 1, put it on the smallest ring . 2 for the middle ring. 3 for the largest.

Then get some chain lube from a bike shop, hardware store, WalMart ....
The type of lube doesn't matter much. Something is better than nothing.

MikeyMK

This is good, though a basic steel full-bouncer like that should have plenty clearance. Still, checking the rear nuts are tight, the wheel isn't loose, and the rear tyre clears the frame, is another critical check for this.

Next thing we'll find out it's because the front wheel doesn't turn...

BlazingPedals

Yup. Not answering a "help me" question from a one-time poster who hasn't even introduced himself and is just going to disappear afterward.