[Delta 1]

I recently decided to try mountain biking. My right knee does like running so I needed a new cardio workout.
I bought a used Felt Q 520 on CL for $80. I’m trying to keep costs low until I know if this is something I really love. I just bought it yesterday and took a short test ride. Took it out today, riding through the neighborhood with my wife, and the chain feels like it’s slipping. When I’m pedaling it’s like it slips out of gear and then catches again, very noisy, my wife thought I was shifting gears due to the noise. Also my rear brake doesn’t work, I think the screw that tensions the pad is stripped.
So, I’m looking for input on new gears and possibly new brakes. Currently the brake levers and shifters are combined so what I’ve gathered is I would need to replace them all, can’t just replace the shifters.
Like I said, I’m trying to keep costs down. I’ve been researching 1x gears. Do certain gears fit certain bikes or can I buy any gears and expect them to fit. My LBS already tried to sell me a new bike($1100) twice so I don’t want to take this bike in for service if I can avoid it. Current gears are 3x8 and it has mechanical disc brakes. It’s also gonna need a new seat, the current one is seriously uncomfortable. Any input is appreciated

 

[Muirenn]

Take it to a different bikeshop and have them give the bike a tune-up. Won't cost as much as replacing gears. And is probably all it needs.

Saddles are quite individual. I like Specialized brand, myself. Have used various models since 2010.

Is this it?

https://www.bicyclebluebook.com/searchlistingdetail.aspx?id=23210

 

[Forest Rider]

You shouldn't need new shifters. They probably need lubricated. The old grease gets hard/sticky over years and the shifter performance is compromised.

The jumping gears is likely a derailleur adjustment.

There are a lot of YouTube videos on how to adjust a derailleur if you're interested in tackling it. But a local shop can make the adjustments super quick and is really cost effective. Shop labor for bicycles is cheap.

There are some things that are just difficult and not very cost effective to upgreade. Such as a 1x on your bike. Many parts will need to be updated for the system to function.

I can understand the shops approach on a replacement bike. I imagine they were suggesting a low lever entry level model bicycle that is ready to ride, when you could instead spend half that cost on an old bike that is still an old bike.
I don't discredit them for that in this scenario.
It doesn't mean you have to purchase, it's just something to consider when figuring how much money it could cost to make an old bike rideable.

There are a lot of folks around here that are definitely bike nerds and will know what your bike is, I couldn't find much on the bike with a short search.

You'll be out probably $500 easily to upgrade to a 1x and change brakes (if yours are beyond service). Depending on the bike you may even need to replace the rear wheel to accommodate a new cassette system.

I'd give your local shop another try. Maybe they just don't want to take on your bike. That isn't too unusual. I have a local shop that prefers to only work on bikes they sell. Another shop is upfront about what they can't service.
Your skipping chain/shifting could be the derailleur hanger that requires adjustment, if the bike even has a hanger.

I barely work on bikes aside from general maintenance. With my somewhat limited experience, I've learned that I don't want to work on low quality bikes, thinking in terms of department store bikes.

Congratulations on your purchase and your pursuit to cycling. A little time and patience and you should be able to get it tuned and ready to go. Replacing/repairing the existing components is a great start before considering costly upgrades to take an older model bike to a bike with newer features.

Oh and one more thing -I missed the question about you seat. Yes, very subjective. What is uncomfortable to you may be comfortable for me. Depends sort of on what makes it uncomfortable to you. A new seat can be costly, as well as very affordable. It's very difficult to experiment too with what works since we pretty much need to just buy one.
I have only had 1 seat out of 4 that don't work for me. Each of the 4 I've had are different than the other too and all are good. Except for that one. They were all stock seats. The one that wasn't comfy was replaced with one I found and decided to just go with it and it was a good decision.