This post is a cross post from mechanics. I have always thought that the WTB/Suntour Grease Guard was the best designed square taper loose ball bottom bracket (photo from velobase.com). With simple routine maintenance, that did not require the bottom bracket being disassembled, they would normally out live a frame.



I had an interesting discovery however in a Grease Guard I had squirreled away for a while (see story below). When I inspected the left side adjustable cup, I was surprised to see it was not from a Grease Guard BB, it was from some sealed loose ball bottom bracket model made by a Japanese company named Yamamoto (similar to Tange they make various models of steel BB and headsets). It appears that the engineers from Yamamoto discovered that the seal of a 99502H cartridge bearing will fit into a bottom bracket cup (see below Graese Guard on the top,Yamamoto cup on the bottom). So they took one of their bottom brackets with rubber spindle seals and then put the cartridge bearing seal behind the bearings; in essence they created the same setup as a Grease Guard; the cup looks to be too shallow as the grease port appears covered by the seal. But since the BB was not designed for the Grease Guard system, it sounds like it would still seal in any loose ball BB cup. Would anyone consider doing this to their loose ball bottom bracket?



This post a little back story. About 15-20 years ago I was about to leave for a century ride down south (south of Santa Cruz, when loose ball bottom bracket in my old Peugeot gave up the ghost. I hurried down to a LBS and they said they could replace it with another loose ball or cartridge for the same price, so I decided on a loose ball and they said they have it ready in an hour; wow great service I thought. Well picked up the pick and took off for my century ride. The ride was none eventful, but the BB felt strange; hard to define but I remember I didn't trust it. So when I got home I replaced it with a cartridge BB, but didn't really inspect the the new to me BB; all I knew was it was a Suntour/WTB Grease Guard (I kept the box) and it ended up forgotten in my parts bin until today. I was arranging by parts pin and remembering the Grease Guard BB from years earlier, I decided to check it out. The first thing I noticed was the below ball bearing retainer that had been turned into a Christmas wreath; the result of installing the retainer upside down. I was happy however to see that the bearing surfaces looked new, with only the only damage being a thin ring that rounded off the the top of the spindle cone.