Calling all Bike experts!

[Juice Box]

So I am trying to fix my somewhat-POS bike (not a name brand, but not a total hunk of junk either). Whenever I go to put a large ammount of force on the pedals (eg: going from slow to fast rather quickly)...the pedals/chain slip ridiculously, and i end up not moving, lol Gotten me stuck in intersections a few times, not being able to move. The only way I can get up to speed is if I do very gradual pedaling...and i mean....gradualll...

I can't really see where the chain is slipping exactly. And if you think I mean the chain falling off, it's not that...because I can pedal right away after the slips, its just the pedals will do about half a turn, not taking the chain with it at all!

Any ideas as to what's going on here? Any way to fix it? The chain is all greased up and as it should be!

Thanks in advance!! =D

 

[conehead433]

Your chain is wore out. Get a new one. You can easily check the chain by attempting to twist it sideways. It shouldn't have hardly any freeplay. I had exactly the same problem before, a new chain did the trick.

 

[Don Vito Corleone]

If I had to guess, my guess would be that your right (rear) shift cable has stretched, leaving your rear derailleur positioned just slightly out of place for each gear.

There is a barrel adjuster on your rear derailleur (the shifter also usually has one) that you can adjust to compensate. It is normally about 1/2" long and covered in knurled black plastic. You turn it counter clockwise to tighten the cable. You will want to try adjusting it a half-turn at a time - it shouldn't take much to get it adequately tight.

 

[fuzzybabybunny]

Make sure the new chain is the right length as well.

 

[jagec]

If your bike is old enough and crappy enough, you'll need new sprockets to go with that new chain. It happened to me once...the bike was fine for quite a while, until I snapped the chain while putting on a particularly high burst of speed up a hill. The new chain exhibited the symptoms you describe, because my sprockets were so old and worn the chain just slipped over the teeth under hard pedalling.

 

[Don Vito Corleone]

Originally posted by: conehead433
Your chain is wore out. Get a new one. You can easily check the chain by attempting to twist it sideways. It shouldn't have hardly any freeplay. I had exactly the same problem before, a new chain did the trick.

No offense but this may not be good advice. If the chain is badly worn enough to cause skipping, changing it will necessitate changing the cogs as well, at meaningful expense. Your proposed method for measuring chain wear is pretty much completely unscientific - different chains have different levels of lateral suppleness, and you can't test one this way. I, for example, have a 10-speed Campy drivetrain on my main road bike - and even a brand-new, $55 Campy chain has loads of lateral flex.

 

[olds]

How ironic. I've always thought that the OP's chain had slipped a cog.

 

[Dirigible]

You can make sure your derailleur is adjusted (assuming you have index shifting) by following the directions here:
Text
for rear

and here:
Text
for front.

Check the chain and gear wear also. I'm too lazy to look that up for you, but a quick search of the Park Tool website or Google will reveal it.

Adding another site about chain and gear wear: Text

Edit: 'Cause I hit reply wayy too quickly, before I'd typed anything.

 

[Juice Box]

Originally posted by: oldsmoboat
How ironic. I've always thought that the OP's chain had slipped a cog.

 

[IHateMyJob2004]

I'm in the worn out sprockets category if the chain is actually slipping on the sprockes.

 

[Fausto]

Originally posted by: IHateMyJob2004
I'm in the worn out sprockets category if the chain is actually slipping on the sprockes.

It's a process of elimination.

First make sure the rear der. is adjusted properly.

Then make sure the chain doesn't have a frozen link that's causing it to skip.

Then, replace chain AND cogs. You can't do one or the other as worn cogs + new chain (or vice versa) = really horrible skipping no matter what you do.

 

[Juice Box]

Originally posted by: Fausto

Originally posted by: IHateMyJob2004
I'm in the worn out sprockets category if the chain is actually slipping on the sprockes.

It's a process of elimination.

First make sure the rear der. is adjusted properly.

Then make sure the chain doesn't have a frozen link that's causing it to skip.

Then, replace chain AND cogs. You can't do one or the other as worn cogs + new chain (or vice versa) = really horrible skipping no matter what you do.

can you define "frozen link" to me please? =)

 

[GalvanizedYankee]

The chain is held together by pins that are also tiny shafts that need to flex.
If one is rusted internally or damaged it won't flex. This will cause the chain to ride up on
the rear sprocket...causing it to slip-a-cog.

...Galvanized

 

[Don Vito Corleone]

To expand on the topic of frozen links, if you find you have a link that is sticky or completely bound up, you can often free it up by lubing it well and firmly flexing it laterally.

 

[Staples]

Sounds like the chain may be loose. I have a POS derailleur on a bike I bought from Costco and had to replace it. It was a pain to do without the tool so I'd pay next time.