Chain Jumping lots of questions.

sketchley

Any ideas why my chain would jump off the front chain ring to the outside when under extreme load (big gear standing up pulling away)? The chain is new, as is the cassette, gears are adjusted perfectly, I got the LBS to check the indexing and to be sure they even moved front mech down a bit. My only thought is that chain ring is worn and new chain highlights this? Is that possible? If so where do a get a 50T chainring for a Sugino Comp five arm chainset? Would a new chainset be a better idea? I guess the current one has done 4,000 miles by now.

Clever Pun

how new is the chain... first ride? you might need to bed it in a bit so use the gears to get you up to full speed after a week maybe you'll be good to torque

sketchley

Clever Pun wrote:

how new is the chain... first ride? you might need to bed it in a bit so use the gears to get you up to full speed after a week maybe you'll be good to torque

Yes brand new and first ride out and it did this twice in the morning on tuesday then once in the evening after LBS adjusted indexing. Middle chain ring is fine even in bigger gears so I've been using that since and not had confidence to try the bigger ring pulling away. I'll give it a week or so and see what happens. Thanks!

Clever Pun

you use the outer ring the most though right? it'll be worn you just need to ride it once you're up and running so to speak.

that or make it a single speed

Greg T

There was an opportunity here to hilariously and gratuitously use the following:

Big Ring
Push
Power
Tip Toes
Eye Watering
Virgin
Lube
Surprise

You should take and F and book yourself into Remedial Finbar Class.

Amateur . . .

will3

Hi - I had this problem - it turned out that my bottom bracket was worn that the chainring had a lot of wobble on, particularly under load.

Grab the pedals and try and twist the chainset side to side. should be no play.

Greg T

will3 wrote:

Hi - I had this problem - it turned out that my bottom bracket

YOU SEE???

The comedic gift that just keeps on giving

GRINDING!

There we could have got that one in . . . .

GOT THAT ONE IN!

I can't stop it

CiB

You can tell by looking at the profile of the teeth on the rings. It's obvious if they're worn - instead of a nice even curve from the tip of each tooth down and back up to its neighbour, there'll be a rearward slant on the forward edge of the tooth leading up to the tip. It's the slant that allows the chain to jump - it slides up the slant and jumps back a tooth.

Greg T

CiB wrote:

teeth on the rings.

tooth leading up to the tip.

slides up the slant and jumps back

It was there - but you had to look VERY hard

VERY HARD

will3

Greg T wrote:

CiB wrote:

teeth on the rings.

tooth leading up to the tip.

slides up the slant and jumps back

It was there - but you had to look VERY hard

VERY HARD

kelsen

Shit-faced before 11am? Chapeau Greg T!

Greg T

I wish . . .

Headhuunter

Clever Pun wrote:

how new is the chain... first ride? you might need to bed it in a bit so use the gears to get you up to full speed after a week maybe you'll be good to torque

Yeah if you put a new chain on without changing the entire driver chain (which although advised is not strictly necessary) you often have to let it bed in a bit before it stops jumping

iPete

will3 wrote:

Hi - I had this problem - it turned out that my bottom bracket was worn that the chainring had a lot of wobble on, particularly under load.

Grab the pedals and try and twist the chainset side to side. should be no play.

This! My BB was rocking all over the place before I realised it was the cause

Paul E

All this worn BB talk is making me think mine is going to let go soon, it has a slight click noise to it, I thought it was the bearing in my back wheel but it stops when freewheeling

Headhuunter

Paul E wrote:

All this worn BB talk is making me think mine is going to let go soon, it has a slight click noise to it, I thought it was the bearing in my back wheel but it stops when freewheeling

It's fairly easy to tell when bearings are loose. For the BB, grab one of the cranks and give it a good wobble if it doesn't feel completely solid and there is some give or rattle, then it's loose. Same with the wheel, grab the top and shake it from side to side, if you can feel it rocking from side to side, however slightly, it's loose...

Kieran_Burns

Headhuunter wrote:

Paul E wrote:

All this worn BB talk is making me think mine is going to let go soon, it has a slight click noise to it, I thought it was the bearing in my back wheel but it stops when freewheeling

It's fairly easy to tell when bearings are loose. For the BB, grab one of the cranks and give it a good wobble if it doesn't feel completely solid and there is some give or rattle, then it's loose. Same with the wheel, grab the top and shake it from side to side, if you can feel it rocking from side to side, however slightly, it's loose...

I just tried this, and threw the bike in to the hedge. What does this mean?

will3

Kieran_Burns wrote:

Headhuunter wrote:

Paul E wrote:

All this worn BB talk is making me think mine is going to let go soon, it has a slight click noise to it, I thought it was the bearing in my back wheel but it stops when freewheeling

It's fairly easy to tell when bearings are loose. For the BB, grab one of the cranks and give it a good wobble if it doesn't feel completely solid and there is some give or rattle, then it's loose. Same with the wheel, grab the top and shake it from side to side, if you can feel it rocking from side to side, however slightly, it's loose...

I just tried this, and threw the bike in to the hedge. What does this mean?

don't do it while riding.

sketchley

Paul E wrote:

All this worn BB talk is making me think mine is going to let go soon, it has a slight click noise to it, I thought it was the bearing in my back wheel but it stops when freewheeling

I'll check the BB later thanks for suggestion.

As for slight click, I've had this a lot, grit in pedal thread was the problem, remove pedals, clean grease and re-insert before replacing BB.

sketchley

CiB wrote:

You can tell by looking at the profile of the teeth on the rings. It's obvious if they're worn - instead of a nice even curve from the tip of each tooth down and back up to its neighbour, there'll be a rearward slant on the forward edge of the tooth leading up to the tip. It's the slant that allows the chain to jump - it slides up the slant and jumps back a tooth.

I can see one tooth that is missing it's point. But assumed this was to help the chain go from lower ring? Could this be it?

sketchley

[quote="Clever Pun"]you use the outer ring the most though right? it'll be worn you just need to ride it once you're up and running so to speak.

that or make it a single speed[/quote]

A gift for Greg this one.

I'm always in the big ring.*


*Except when going up a steep hill

sketchley

[quote="Clever Pun"]you use the outer ring the most though right? it'll be worn you just need to ride it once you're up and running so to speak.

that or make it a single speed[/quote]

A gift for Greg this one.

I'm always in the big ring.*


*Except when going up a steep hill

will3

Sketchley wrote:

CiB wrote:

You can tell by looking at the profile of the teeth on the rings. It's obvious if they're worn - instead of a nice even curve from the tip of each tooth down and back up to its neighbour, there'll be a rearward slant on the forward edge of the tooth leading up to the tip. It's the slant that allows the chain to jump - it slides up the slant and jumps back a tooth.

I can see one tooth that is missing it's point. But assumed this was to help the chain go from lower ring? Could this be it?

probably meant to be that way.

Worn teeth look more like shark fins. Tend to be really pointy on top.

Can't say I've ever had a worn chainring cause the chain to jump though.

mudcow007

possibly bent chainring?

Paul E

Sketchley wrote:

Paul E wrote:

All this worn BB talk is making me think mine is going to let go soon, it has a slight click noise to it, I thought it was the bearing in my back wheel but it stops when freewheeling

I'll check the BB later thanks for suggestion.

As for slight click, I've had this a lot, grit in pedal thread was the problem, remove pedals, clean grease and re-insert before replacing BB.

I was spinning it without using the pedals to rule it our, Might take off the cranks tomorrow and have a look after giving them a damn good yank

will3

Paul E wrote:

Sketchley wrote:

Paul E wrote:

All this worn BB talk is making me think mine is going to let go soon, it has a slight click noise to it, I thought it was the bearing in my back wheel but it stops when freewheeling

I'll check the BB later thanks for suggestion.

As for slight click, I've had this a lot, grit in pedal thread was the problem, remove pedals, clean grease and re-insert before replacing BB.

I was spinning it without using the pedals to rule it our, Might take off the cranks tomorrow and have a look after giving them a damn good yank

before you do that - it's not the front derailler cable end hitting the crank is it?

Headhuunter

Seriously though, the most likely problem is that you have fitted a new chain to a relatively worn drive system.... As long as the chainrings and gears are not too worn, ie have not snapped off, or don't look like shark fins, just give it some time to see if it beds in... Or replace the entire drive chain.

sketchley

Headhuunter wrote:

Seriously though, the most likely problem is that you have fitted a new chain to a relatively worn drive system.... As long as the chainrings and gears are not too worn, ie have not snapped off, or don't look like shark fins, just give it some time to see if it beds in... Or replace the entire drive chain.

Thanks sound like good advice, although testing it will be fun as I drew blood when my right knee hit the handlebars when it jumped on Tuesday!

Re: replacing entire driver train, as granny ring and middle ring are fine would replacing the big chain ring not suffice? Where does one buy such and thing and make sure it's compatible? If I did as far as replacing the entire chainset I guess it's wise to do the BB as well? Also are chainset "speed" dependent do I need to find a "9 speed" tripple chainset?

Question question questions.....

Headhuunter

Sketchley wrote:

Headhuunter wrote:

Seriously though, the most likely problem is that you have fitted a new chain to a relatively worn drive system.... As long as the chainrings and gears are not too worn, ie have not snapped off, or don't look like shark fins, just give it some time to see if it beds in... Or replace the entire drive chain.

Thanks sound like good advice, although testing it will be fun as I drew blood when my right knee hit the handlebars when it jumped on Tuesday!

Re: replacing entire driver train, as granny ring and middle ring are fine would replacing the big chain ring not suffice? Where does one buy such and thing and make sure it's compatible? If I did as far as replacing the entire chainset I guess it's wise to do the BB as well? Also are chainset "speed" dependent do I need to find a "9 speed" tripple chainset?

Question question questions.....

I don't think it's possible to just buy a big ring in isolation, I think you literally have to change the entire front set of chainrings AND the rear cassette.... Not the BB.

Yes, you need to replace like with like so that the 9 speed chain you have (I assume) will work with the 9 speed cassette. You could change to a double chainring if you like, but then yuo would also need to change your gear shifters. If you have 9 speed/triple shiifters then stick with that... But I would give it a week or so to see if it settles in. Try to to pile to much pressure through the chain to start with, perhaps use the middle ring and don't mash....

veronese68

I think your big ring is quite worn from s omuch use. Just for Greg. When I looked at it the teeth did look pointy, possibly a touch too much. When you're passing with my tool (Greg) we can have a quick look. I think you can change just the big ring.

sketchley

Perfectly possible to remove just the big ring on my chainset. So if you can buy a spare....