Chain Mileage & Shimano Alivio 8-Speed Shifter Jumping Gears Issue,Help

How many miles should I replace the chain?
The bike is just over 6,000 miles (about 9656 km).
Shifter Problems
Shimano Alibio 8-stage gearbox
On my bike, when I shift from high gear to low gear, I go up one step and fly three steps in the next shift.
The cable was replaced and the gearbox was adjusted, but this phenomenon continues.
The shifter also indicates that the gear will fly.
Cable change and delay adjustment of wife bicycle is working properly.
I hope the explanation is conveyed correctly.

thank you.

A simple gauge to measure chain wear is available on the market. Available at Amazon and local bicycle stores. It is easy to use.

Thanks, I will get a chain wear tool. I also ordered a new shifter

seems like it will work.
just that chainbreaker might be the first to go if you use it…be warned.

I got the tool set, but the chain was not good. I wonder if I needed a replacement if I ran 6,000 miles.

Yeah, to use a chain cutter, you need a little practice to fit the old chain exactly.

Make sure the interval between pulley and cassette is correct. The low gear requires a gap of about 5-6 mm between the pulley teeth and the sprocket teeth. Use the B adjustment screw of the derailleur for this adjustment. If the gap is too large, the gear may jump (multi-gear jump).

Thanks, this will be new to me. I’ll check out a few videos.

The gear could be successfully activated. The other day, gear change was good. There are not many hills in Florida. lol

Chain exchange is often the solution to change speed trouble. It’s great to see everything and move smoothly. 6000 miles lasted very long as a chain. Old chains cause other problems such as sprocket wear.

By the way, when replacing worn chains as a result of long use, it is wise to replace the rear cassette (or free wheel) at the same time. Since the sprocket’s tooth shape is sharpened into a new shape by a worn chain, the sprocket in the cluster significantly accelerates the chain wear.

Before installing the chain, I like to make sure that the delay speed works perfectly. It’s easier to do that. After that, adjust the index slightly as needed.

I changed the chain a few days ago, but when I rowed the bicycle, I got out of the cassette and I could change the speed without problems at the bicycle stand.
When I replaced both bicycle cassettes today, everything is working fine.
Thank you for your cooperation. Attach a photo of the bike stand. The square material (6x6) is cut so that it can be bolted to the bicycle rack. This will support your bike. I prefer the condition because the front wheel is stabilized on the ground.