aftermarket chainset to replace 10 spd 105 5700 model

[confusedcyclist]

If anything, the outer ring is looking worn, inner not so bad, so why might I perceive slipping while in inner ring with this new chain?

 

[Yellow Saddle]

There's nothing wrong with those chainrings and I cannot see how the chain could skate over them. Any skating that happens was as the cassette side.
Since that chain is new (I measured it for you), my guess is that you have fitted a new cassette and now you are experiencing problems.

Edit: Skipping is when the chain vacillates between two sprockets on the cassette.
Skating is when the chain lifts up and runs straight over the top of the sprocket without engaging in the teeth.

 

[Yellow Saddle]

This is what a worn chainring looks like. It is overlayed onto a new one.

This is what I call a stage II worn ring. In stage 1 the cogs (teeth) point clockwise. Eventually the little sharkfins wear down and you get what you see here.

Here's a Stage I worn ring.

Notice how the wear pockets make it appear as if the cogs now point to the right.

Your rings are nowhere near this stage, perhaps the big one just a bit.

 

[confusedcyclist]

OK, so skating must be ruled out for the inner ring as it's practically like new. Which means it's more likely that skipping on the cassette is the problem?

The cassette is only 6 months old, this bike being barley ridden since last summer (I had it serviced and the cassette was replaced after a crash). But there have been no problems with running on the little ring before I removed, cleaned and re-fitted the chain rings and put on a new chain. Bolts are all tightened correctly with torque wrench too.

I didn't lube the chain last night mind, I assume the wax that comes on the them is adequate, doubt that's the problem though.

 

[Yellow Saddle]

OK, so skating must be ruled out for the inner ring as it's practically like new. Which means it's more likely that skipping on the cassette is the problem?

The cassette is only a 6 months old, this bike being barley ridden since last summer (I had it serviced and the cassette was replaced then). There were no problems with running on the little ring before I removed, cleaned and re-fitted the chain rings and put on a new chain. Bolts are all tightened correctly.

I didn't lube the chain last night mind, I assume the wax that comes on the them is adequate, doubt that's the problem though.

OK, before we proceed, first identify the problem and describe it adequately. Find out what is happening where. It is stupid to speculate based on false premises.

 

[confusedcyclist]

I'll get it in the stand later. Thanks for your patience.

 

[User16625]

If anything, the outer ring is looking worn, inner not so bad, so why might I perceive slipping while in inner ring with this new chain?

A new chain on worn sprockets is worse than a worn chain on worn sprockets/chainrings. The wear mismatch between a new chain and an old sprocket means the chain doesnt mesh with the sprocket fully, and under load will make the chain jump. The smallest chain ring is most susceptible to this as there are fewer teeth, this means the load is spread along fewer teeth, amplifying potential issues.

You can put a new chain on used sprockets provided that you renew the chain before it wears too much. I am actually on a 3rd chain on my CR1 without chainging the other parts. However I will replace both the chain rings and the cassette when this chain is replaced.
On my bikes that have very small chain rings, I intend to change them after 2 chains.

 

[Yellow Saddle]

A new chain on worn sprockets is worse than a worn chain on worn sprockets/chainrings. The wear mismatch between a new chain and an old sprocket means the chain doesnt mesh with the sprocket fully, and under load will make the chain jump. The smallest chain ring is most susceptible to this as there are fewer teeth, this means the load is spread along fewer teeth, amplifying potential issues.

You can put a new chain on used sprockets provided that you renew the chain before it wears too much. I am actually on a 3rd chain on my CR1 without chainging the other parts. However I will replace both the chain rings and the cassette when this chain is replaced.
On my bikes that have very small chain rings, I intend to change them after 2 chains.

No.

You are assuming that driven sprockets (cassettes) and driving sprockets (chainrings) in a circuit with a slack return run malfunction in the same mode. They don't.

 

[confusedcyclist]

OK. Here's what I can gather having cycled home and toyed around in the garage.

I am 100% only having problems when the chain is on the inner chainring, it definitely doesn't matter which cassette cog I'm using. Based on the definitions provided by @Yellow Saddle, it seems to be skating, rather than skipping, there's no side to side movement of the chain that I can see from the saddle. The problem couldn't be replicated in the bike stand, presumably because I can't put enough power into the pedals, or there is little to no resistance on the drive chain. It's hard to tell for sure without the side view. But I'm 90% sure the chain is skating over the inner ring under power, and on the face of it, the issue doesn't lie with the cassette (but reserve the right to be wrong)

I say that because when stationary in the saddle and applying force to the cranks while holding front and rear brakes, the cranks lurch with a harsh clunk before the chainring grabs the chain again. When out on the road and in the garage, this isn't happening when shifted to the outer ring.

I swapped out the chain for the older one and the problem with the inner chainring has disappeared. For the record, it was definitely a new chain I fitted, double checked it and it's a 10spd for my 10spd drive chain, sealed in the package, cut the right length, and no stiff links.

 

[confusedcyclist]

bumping this thread because this problem is bugging me!

 

[User16625]

bumping this thread because this problem is bugging me!

Sounds to me like you need a new chain ring.

 

[Ajax Bay]

I am 100% only having problems when the chain is on the inner chainring, it definitely doesn't matter which cassette cog I'm using. .. ... seems to be skating, rather than skipping,. . . . on the face of it, the issue doesn't lie with the cassette (but reserve the right to be wrong) I say that because when stationary in the saddle and applying force to the cranks while holding front and rear brakes, the cranks lurch with a harsh clunk before the chainring grabs the chain again. When out on the road and in the garage, this isn't happening when shifted to the outer ring.
I swapped out the chain for the older one and the problem with the inner chainring has disappeared.

Right I'll take a stab at this, and please allow that I'm making assumptions/guessing. Consider it unlikely that your small chainring is fecked, but by all means post an image.
The amount of torque a rider can exert is the same whichever chainring is in use. But when you're in the small chainring the work the rider is doing by driving the crank round the tension in the chain is greater by a factor of large chainwheel teeth / small chainwheel teeth (say 47% for 50-34). This means that skating will be more likely when you're in the small chainwheel, and probably mid range of cassette (those sprockets are used more). Why does the chain not skate when you're in the large chainwheel - because the chain force is less. When you swapped back to the old chain the worn cassette said 'ooh that's just right - worn like me' - no skating. You said the cassette was 6 months old (from new) - but it's the distance you've ridden it and the style of riding which will determine the amount of wear. And if you've ridden it any distance with an elongated chain (ie your old one) it will wear quickly.
My recommendation is to refit the old chain, use the combo till it misbehaves (getting a new cassette in the meantime), and then replace both. Never replace a cassette without replacing the chain at the same time. Resolve to be a little more diligent about measuring your chain and replacing it when it reaches 100.06% elongation.
HTH

 

[confusedcyclist]

Thanks Ajax, makes complete sense. The inner chainring looks perfectly functional, no damaged teeth to speak of. I managed to replicate the skating on the old chain on Friday, though only once while out on a hilly 30 mile ride so I'll do as you suggest and get a new cassette in stock for when it gives up the ghost completely.