Bought my son a Trek Marlin 6 for xmas and today a few rides in I noticed that the bottom bracket bearings are just exposed like this. LBS that sold us the bike says that it comes from Trek like that and is standard, but I’m skeptical. It feels like plenty of water/mud will come into contact with that bearing and shorten its life. None of the other bikes I’ve owned came built this way (Scott, Ibis, YT); am I missing something, or is the bike missing something?
by Cajun-McChicken
4 Comments
Normal for that type of bottom bracket, it’s a sealed bearing. The shop is telling you the truth.
Those aren’t the bearings you are seeing but the grooves for the removal tool to latch onto. The bearings are not visible but sealed inside.
That is a standard square taper cartridge bottom bracket. The bearings are sealed, they should last for years of problem free riding.
This is what bearings look like on a three-piece crank. That gap is normal, that is what almost every bike looked like 25 years ago.
More modern bikes use two-piece pranks where the bearings sit outside of the frame. While there’s no visible gap between the crank and the bearing, that doesn’t mean the bearing will last any longer.
Those are RS bearings – go touch grass.