Hi - I broke a bottom bracket on my 2019 Trek Marlin 5 and need to replace it. The bottom bracket was a VP-BC73, 73Lx126.

I can't seem to find that exact spec online to buy a new one.

I found one that is 73x122. Will that work? Anyone have any idea what the L in the 73L means? I assume Large, but not sure what that would mean.

Thank you.

73 is likely the width of your BB shell. 126 the length of the shaft. So half of those 4 mm's shorter the one you found might leave your chain wheel rubbing the stay and your front DR not lined up.

It's a BSA threaded shell though so you have a lot of options. Why not just ask your nearest Trek Dealer. Sure you might pay 40 buck instead of 18 bucks, but you'll know you got the thing you need. They might even install it for you for not much.

You can be pretty confident there is something out there that will work.

Thank you! I don't like my nearest Trek Dealer. I don't trust him, starting from when he sold me a $25 kickstand as if it was the only option, when there's also a $15 kickstand. But there's other reasons not to like him.

But there's another dealer 15 minutes away, so good idea, I'll probably call them tomorrow.

Have a good night.

Most local bike shops should have a Shimano replacement bottom bracket for $20 to $30 and might charge $25 to $35 to remove your old one and install your new one. First get the correct dimensions for your existing BB then call a shop to see if they have it in stock and if yes find out the price for the part and cost to install. If your BB is seized then labor cost will be more as more time will be needed to remove the old one. If the threads on your BB shell need to be recut there will be more time and cost. Hopefully you'll find a LBS and get yours replaced for $60 give or take.

Nope, the overall length should match within one millimeter. At best, the short spindle will screw up your chainline for smooth shifting and driveline. At worst, it will jam the inner chainring into the chain stay.

All 73 mm bottom brackets are BSA (English) threaded and JIS taper. Right now Shimano has discontinued their BB-UN26 and BB-UN55 units, replacing them with BB-UN300. Distribution of these looks spotty, so you may have to settle for brand-X. Good luck.