Loftydog

Hello all, I have a new to me Trek 820 that I think I may need to replace the crankset, there are 2 teeth next to each other missing from the largest chainring. So far it hasn't been an issue as I haven't been using that high of a gear yet. From what I've read so far, looks like I should replace it. The sticker on it says SR Suntour XR PFF 120 and the Trek website says the 820 has a Shimano Tourney TY301, 42/34/24, 170mm length. I'm guessing mine is an older setup or was already replaced. Can instill use a Shimino? So far in looking around, I can get a new Shamino for not much more than a used Suntour (don't see new ones).

Thank you all in advance.

SoCaled 

Not necessary to replace the whole crankset. You could just replace that individual chainring.
Edit: I may be wrong, not sure the largest ring comes off that crank? how about this - https://www.ebay.com/itm/296287326441 does that look the same?

grumpus

I wouldn't worry about it as long the chain stays on the ring, which it probably will (if there are bent or ragged bits you can straighten and smooth them, if the ring is actually warped you will need to straighten or replace it). It's common for mountain bikes that get ridden in rocky conditions to lose a couple of teeth, usually equidistant between the cranks on one side only, which depends on the rider's favoured foot - I ride left foot forward, so it will always be the bottom teeth when the drive side crank is at 9 o'clock that get ripped off.

Bill Kapaun

Are you sure there aren't "teeth missing" at regular intervals around the ring.
aka "shift aids".

Loftydog

SoCaled, yes that looks just like it! With shipping I can get the Shimino on Trek's website a little cheaper and brand new. But it's not a big difference and it might be better to leave well enough alone?

Loftydog

Grumpus, thank you for the info!

Loftydog

Yeah, there are no missing ones like that, just the two, but that is good to know, didn't know about shift aids, ty