How to Fix the Gears on Your Bike!

I’m clicking the high switch to change to a higher gear and it doesn’t go up what should I do

I want help!!
My bike has a Problem in shifting
For eg :- when i want to shift to 1st gear it shifts to 2nd gear and doesn't go anymore up and if i shift to 2nd gear it shifts to 3rd and if shifted to 3rd it goes to 4th and so on .. i hope you would help me out

I haven't seen a bike so smooth in my whole entire life. My bike is older than I am.

when i have 1 gear at front and the back my derailler touches the spokes on the back whele,what should i do??

In my neighborhood went people can't adjust gears they trow bike yo the garbage 😆I pick up fix n sell 🙂.

i got a 6 speed and at first it was stuck in 6th and i couldn't budge the shifter and now i got it to stay in third i just dont know what the sweet spot is

My issue with my gears on my bike is that when i change it to any number on my gear shifter its always the gear ahead of it. So lets say i put it to gear 7 on my gear shifter on my handlebar it will be on gear 6 instead of 7 and lets say change the gear to number 1 gear the chain will just come of of the gears and so i have to put it to gear 2 to be able to have it on gear 1

HELP !!
i have bike powered with shimano gear system. it has 3 front cogs and 7 back cogs
the problem is it only falls in the 6th-7th gear it doesn't fall in bigger gears, what should I do?
good engineers i need your help