When replacing a chain at what angle should the rear derailleur be?

[Lauris]

So uh I went for a ride and now it seems some cogs jump. Surprisingly cogs that I don't normally use (apart from 1)
It bearable, just have to now remember which gears not to go into
In total 3 cogs jump

 

[Shearwater Missile]

So uh I went for a ride and now it seems some cogs jump. Surprisingly cogs that I don't normally use (apart from 1)
It bearable, just have to now remember which gears not to go into
In total 3 cogs jump

Jumping from one sprocket to the next or skipping over a sprocket ? If the former then barrel adjuster just needs adjusting. If the latter which I suspect then it is because the cassette has worn. If that is the case then you`d need a new cassette to run with the new chain for a few hundred miles and then you can put the old cassette back. It depends how worn the chain was before you changed it and not how many miles it had done as in winter chains take a punishing.

 

[Ajax Bay]

So uh I went for a ride and now it seems some cogs jump. Surprisingly cogs that I don't normally use (apart from 1)
It bearable, just have to now remember which gears not to go into
In total 3 cogs jump

Surprise, surprise! As I said on the other thread, take the new chain off, put it safely in a bag for later, refit the old chain and ride on. In case you didn't have time to read my advice, I've quoted it below (not the done thing I know) for ease of the OP's access - I have emboldened the way ahead. On an 8 speed "remember which 3 gears [means sprockets, could be 6 or 9 ratios not available] not to go into."

You won't need to change your cassette and chain every 1000 miles. You don't need to change your chain now. It has not started skating, has it?
By all means change your chain, but hold onto the replaced chain. Ride out and either it'll skate or it won't. If it doesn't: happy days. If it does [skate], put the old chain back on and ride on, till it skates. Put the new chain back in its packet. Buy a cassette in the next month. When the chain eventually skates (it will invariably only jump one half link), replace both chain and cassette. I'd expect you get 3000 miles out of a new chain and cassette combo. Personally get 5000 miles (9 speed) when I let the chain and cassette run to their joint life's end, and this is a repeated experience. Given your drivetrain is 8 speed, faffing around trying to change the chain at an arbitrary distance/percentage elongation is not worth it.

 

[shornby]

Photo 1 is in biggest rear cog and front on biggest ring
Photo 2 is in smallest rear cog and front on the biggest ring.

I feel that in photo 1 the angle of the rear derailleur is a bit too much??

 

[shornby]

Hi ----- I suspect your rear mech cannot handle such a large Sprocket -- Thats why one photo looks ok and the other not ---- check out the Mechs limits