Repair older Trek?

[Mr. Bell]

            A co-worker gave me an older Trek mountain bike for my twelve-year-old to use to ride to and from school. Since this will be his first time riding a bike to and from school, I didn't want to invest hundreds of dollars on a new bike (he's tall for his age and has outgrown boy's bikes).

The second-hand Trek was stored outside in my co-worker's backyard and needs the following parts:

New derailleurs
New tires and tubes
New chain
New gear cabling
New seat

I can handle putting the tires and seat on myself (Amazon seems to have those parts at fair prices). I'm looking for thoughts on replacing the derailleurs, chain and gear cabling.

My son is only going to use this to transport himself to and from school. Maybe the occasional short ride with me or his older cousin that lives nearby.

Would you spend the $ on repairs or just purchase an entry-level road bike from Amazon, Target or Walmart?

[G_M]

Hi. No bike waste! Trek 4300 is certainly a nice classic MTB and my personal opinion would be to repair it. Have to appreciate quality bicycles such as Trek; your offspring will enjoy it Are there 7 or 8 gears on the back? Can't confirm clearly from the photo. You should be able to find derailleurs (eg. Alivio groupset) at a good price point also on ebay.

[Joe_W]

Fix it. You need to consider that a lot of those paets are consumables anyway (tyres, chain, tubes, cables, housing). Throw in new housing (both brakes and shifters) as well, plus break pads! A low-ish end shimano rear dérailleur is good enough, though you can get a cheap NOS (new old stock) better one as well. As far as I can recall, from 7 - 9 (mtb: 10) gears in the back, the RDs were interchangeable, so don't worry about the exact model the chain should be gear number specific, though.