Chain jumping/slipping under load

[Georgew]

Oops. I replied to the wrong post. The picture was supposed to be in reply to d8veh's post about the chain maybe being too long.

I'll get a photo from round the back when I get a break and post it up.

Thanks for your help.

Ah weel to answer his query you would need to photograph the whole transmission from chainwheel to the rear Der.

 

[hobbes748]

I'd say that the chain is just too long so it doesn't have enough tension. Put it in bottom gear and show us a photo of the rear derailleur position from the side.

 

[hobbes748]

To check if the hanger is bent the image must be taken from directly behind the bike in line with the Rear Der and focusing on the Rear Der showing the chain on a sprocket. The top pulley should be positioned directly below the sprocket bearing the chain. If it isn't then the chain will constantly be slipping on the sprocket teeth as it will be pulled sideways by the top pulley.

Your image give no information re this I'm afraid.

A stiff link...when the chain is moved backwards it will jump as it moves over the teeth of the sprockets on the cassette.

 

[Georgew]

View attachment 21210

Looking at the chain it does seem that it's not too long. It's very difficult to see from your image if the pulley is directly below the engaged sprocket. If you do not have a stiff link then I suggest your local bike shop and ask them to check the Gear hanger. Where do you live exactly as if near I'd be happy to take a look as I have a fully equipped workshop. I'll PM you with my location which is near Cupar in Fife.

 

[hobbes748]

Looking at the chain it does seem that it's not too long. It's very difficult to see from your image if the pulley is directly below the engaged sprocket. If you do not have a stiff link then I suggest your local bike shop and ask them to check the Gear hanger. Where do you live exactly as if near I'd be happy to take a look as I have a fully equipped workshop. I'll PM you with my location which is near Cupar in Fife.

Thanks for the offer but I've got it booked into a shop round the corner for 9:00 tomorrow. I just can't stand it any longer. But if no joy there I'll be borrowing the wife's kiddie wagon and heading over the new bridge (I'm in East Lothian) to pay you a visit.

As for the pulley - in real life it does appear directly below but doesn't seem totally vertical - perhaps only 1 or 2 deg off plumb. Taking a photo at just the right angle (without lying on the wet pavement) was quite tricky. That was the best shot I managed from about 10 atempts.

 

[Georgew]

Thanks for the offer but I've got it booked into a shop round the corner for 9:00 tomorrow. I just can't stand it any longer. But if no joy there I'll be borrowing the wife's kiddie wagon and heading over the new bridge (I'm in East Lothian) to pay you a visit.

As for the pulley - in real life it does appear directly below but doesn't seem totally vertical - perhaps only 1 or 2 deg off plumb. Taking a photo at just the right angle (without lying on the wet pavement) was quite tricky. That was the best shot I managed from about 10 atempts.

The thing is it can be off-true in different planes and to check it's useful if you have one of these.
http://www.chainreactioncycles.com/x-tools-pro-gear-hanger-alignment-tool/rp-prod122319?gs=1&utm_source=google&utm_term=&utm_campaign=Chain+Reaction-UK-PLA-PLA-All-DT-SE-Shopping+QLB+Generic+Desktop&utm_medium=base&utm_content=mkwid|sHXzK4RKZ_dc|pcrid|161850070953|pkw||pmt||prd|439096UK

 

[EddiePJ]

Just an observation from your first photo. Is the wheel sitting completely in the rear drop out?

 

[hobbes748]

Just an observation from your first photo. Is the wheel sitting completely in the rear drop out?

Yeah, I don't know why it looks like that. The paint seems to fall off if you look at it too hard. I noticed it after I got a puncture a few weeks ago. Removed the wheel and carefully refitted but that's it seated.

 

[chris_n]

What's going on with the diagonal marks on the chain? Certainly looks like its not indexed properly to me (or mech hanger is bent ). Speed sensor magnet could do with truing up too.

 

[tommie]

That`s the oddest shape of a derailleur i`ve ever seen,

New derailleur and possibly hanger, looks like it `s got a thump somewhere.

 

[Deleted member 4366]

The one thing nobody has mentioned is the front sprocket. When mine was jumping on all the gears, I replaced the chain and cassette because I felt guilty about my lack of servicing them, but afterwards, it was just as bad, if not worse. Then I kicked myself when I looked at the front sprocket and saw that it was like a saw blade.

Everything looks normal in the photos and you've checked the obvious, so I'm going to put my money on the front sprocket.

 

[D C]

It may be the camera angle but the chain looks wider than it should be for a 9 speed cassette.
Maybe if so a new good quality 9 speed chain and cassette will sort it and if not it's not a waste of cash as you will need them eventually.
I've had derailleurs bent more than yours appears to be with no chain skipping though issues with indexing which I've fixed by judicious bending back by hand.
I'll bet the shop changes cassette, chain and derailleur and that will hopefully fix it.
9 speeds might be causing a problem with a single chain wheel up front as the cassette needs a narrow chain and sometimes a single chain wheel can be a bit wide for a narrow chain.
Dave.

 

[Georgew]

The one thing nobody has mentioned is the front sprocket. When mine was jumping on all the gears, I replaced the chain and cassette because I felt guilty about my lack of servicing them, but afterwards, it was just as bad, if not worse. Then I kicked myself when I looked at the front sprocket and saw that it was like a saw blade.

Everything looks normal in the photos and you've checked the obvious, so I'm going to put my money on the front sprocket.

This is a new bike so it's unlikely that the chain-ring's teeth are so worn as to cause this problem. If the chain-ring has been bent and has a wobble then that could be responsible but it's more likely to be the rear Der hanger being out of true.
That said...everything is mere speculation until a mechanic first checks the basics.

 

[hobbes748]

What's going on with the diagonal marks on the chain? Certainly looks like its not indexed properly to me (or mech hanger is bent ). Speed sensor magnet could do with truing up too.

The marks on the chain might be due to my (fruitless) on the fly cable adjustments.

The bike has been dropped off at the shop so I'll update you all later.

Thanks again for everyone's input.

 

[Deleted member 4366]

This is a new bike so it's unlikely that the chain-ring's teeth are so worn as to cause this problem. If the chain-ring has been bent and has a wobble then that could be responsible but it's more likely to be the rear Der hanger being out of true.
That said...everything is mere speculation until a mechanic first checks the basics.

How long does it to to check it? It's easy to eliminate it as a possible cause by checking it rather than gamble on it not being the cause by using probability.

 

[Steve A]

I had same problem, frustrating that when you put power down there would be slippage. I ended up changing the chain and cassette which solved the problem. These bikes can put down (with your help) a lot of power and faster, so its inevitable that it will need more regular maintenance than a standard bike. I change my chain as and when it shows wear using the chain wear tool, this is cheaper than replacing cassette.

 

[Georgew]

How long does it to to check it? It's easy to eliminate it as a possible cause by checking it rather than gamble on it not being the cause by using probability.

You talked about your chain-ring looking like a saw blade and presumably you meant the typical "shark's fin" profile which is caused by extensive wear. Given that this is a new bike it's very unlikely I would have thought that this is the cause and God knows I have changed hundred's of chain-sets with this damage caused by worn chains. It does seem sensible to assume that the cause of the problem lies elsewhere and in my experience would be found in a stiff link or the Der hanger being distorted and especially so given the bike has been delivered by carrier.

 

[hobbes748]

And the problem was.......

The cassette.

The shop was great. Checked all the usual suspects but nothing was out or made a difference.

Changed the cassette and suddenly all is well again.

I've no idea what they should look like so here's a picture of the critter.

 

[Deleted member 4366]

That cassette looks OK to me. If you want, you can send it me. I'd gladly put it om my bike, and bet anything that it won't slip. In fact I'll pay for your new cassette if it does slip. Most likely, your gear indexing was just a bit out and they put that right when they installed the new cassette,

 

[hobbes748]

That cassette looks OK to me. If you want, you can send it me. I'd gladly put it om my bike, and bet anything that it won't slip. In fact I'll pay for your new cassette if it does slip. Most likely, your gear indexing was just a bit out and they put that right when they installed the new cassette,

I dunno. On closer inspection the little one looks a bit wobbly to me.