knightsbliss12

Right I've got a bike which rides ok on the level but soon as I put pressure on or go up hill its almost like I lose drive I get a clonk like its jumped to a different gear but it in right gear,and it dose it regardless what gear in in l,any help would be much appreciated

awfulwaffle 

Sounds like the freewheel or freehub (depending on how your bike is equipped) may have some pawls that are failing to engage. What bike is it?

ThermionicScott 

Or it could be a worn-out cassette, chain, and/or chainring. How many miles on them/do you do any maintenance?

Pictures are always welcome, even if they don't prove to be helpful.

knightsbliss12

Its the appollo xc.26 se,bike was given to me so unsure of miles that it has done,dont think its had any maintence done of it as far as I no,I have done maintence on bikes in past

knightsbliss12

. Hope the pictures help

Bill Kapaun

Those cogs do appear to have a lot of miles.
Also- Check your chain for stiff links.

In fact, after looking at pic 2, see how the chain is "sagging"?
The pins should line up in the "valleys" between the teeth.

It appears very worn out and stretched.
Measure it. 12 link sets should be 12".
@ 12-1/8" in that distance, it's considered very worn.

ThermionicScott 

Aha! Some shark-finning can be seen on the big/middle chainrings and several of the cassette sprockets, meaning that they've been run with an elongated chain. This is a good webpage to read if you hadn't stumbled across it yet: Chain Maintenance

The bad news is that you probably need a new cassette, chain, and crankset (the chainrings appear to be riveted on), but the good news is that with better maintenance, you should get a lot of miles out of your next set of these components.

knightsbliss12

I measured 12" and there's 14 links with in the distance,would I have to replace everything to get bike working properly again?

hueyhoolihan

i would replace chain, cogs, and possibly chainrings.

Bill Kapaun

Likely

knightsbliss12

Righto will ave a look into I that should fix the problem in having ?

onespeedbiker

Your drivetrain may or may not be trashed; but it is dirty. Even if your chain is stretched (chains don't stretch, they elongate, but we'll use the word stretch for clarity) that might not be what is causing the skipping problem. When you measure the chain, you choose a link pin at random for the 0 point. Center your measuring tool on the center of the pin and measure 12 "; at 12" it should be near center on another pin. The determination if the chain is overly stretched is relative to the 12" measurement, center pin to center pin. If the 12" mark is still center on the pin, then the chain is fine. If the 12" mark is 1/16" short of the center of the pin, then the chain is worn, but shouldn't damage the drive train. If the 12" mark on your measuring tool is 1/8" short or more of the center of the pin, the chain may have stretched too far. However, even if the chain is over stretched, a new chain may still work. The new chain will need to re-grind the teeth profiles on the cogs and chainrings, and if they don't skip in the process, you should be good. Saying that your crankset chainrings are really worn and should be replaced; and since they are permanently attached to the crank spider, the entire crankset will need to be replaced. The only upside to this is a similar (inexpensive) replacement crankset should set you back no more than $25-$35..https://www.amazon.com/s/ref=sr_nr_p_...89011(assuming the Bottom Bracket is the right size.

How about a picture of your derailleur; if it's not properly tensioning the chain, it could explain the chain skipping. To check the pawls, place the front wheel against a solid object and stomp down on the pedal and see of the cassette turns.

knightsbliss12

When I stomp on pedal casstte stays still but chain jumps off the chain ring

Antieverything

What kind of shifter does it have? Could be as simple as tightening down the screw that holds it to the mount.

knightsbliss12

knightsbliss12

Chain just stays in gear but when I go up hill or add pressure feels like it jumps gear but stays in same gear

Antieverything

Ok that eliminates shifter/derailleur issues. If it skips in every gear on the rear then it's more then likely the chain. The way it sits high on the teeth would make it skip. Similar to when people try to run a 3/32 road chain on a 1/8" track cog.

02Giant 

The chain rings on the crankset are worn out, it is time to replace the crankset, and the chain at a minimum, maybe even the cassette.

AnkleWork

The chain has shrunk?

knightsbliss12

Chain is elongated when you try to push chain in to chain ring teeth some of the chain pushes out,I just measured 12" n counted the links between was told 12" would be 12 links and it was 14 links

cny-bikeman

You will have to replace chain, cassette and chainrings, questionable expense on that bike.

Bill Kapaun

Can't be-
Now it DOES look like you might have 12 link sets in 14".

In pic 2, it's beyond obvious that your chain is severely worn.
The mating parts are likely to be SEVERELY worn because they wear in together.
As the chain gets worn, you reach a point that only ONE tooth per sprocket is shouldering the entire load and thus wears rapidly.
When parts are new, the sprockets/chain mesh over multiple teeth and they "share" the load.

onespeedbiker

Again, the idea that your chain has stretched 2 links is absurd! Forget about the number of links as it has nothing to do with a stretched chain. check out this video (using a 12" ruler starts at 1:25) chain

Also how about a photo of your rear derailleur..

klmmicro

Looks like you need a chain and chain rings. The cassette actually looks serviceable by the photos provided. Take everything apart and scrub it all clean. Replace your chain rings and repack the bottom bracket while you have the cranks off. It would also be prudent to repack the rear hub as well to ensure everything has fresh grease and no pitting in the races.

knightsbliss12

Sorry misunderstood about chain stretch and links but thanks for vid I get it now..