May 3rd, 2011
HSC is making some of the nicest ceramic bottom brackets that we have yet seen. Now that there are so many different standards for bottom brackets we thought this a good time to try and differentiate the standards and help people figure out what is the right bottom bracket for them. Currently there are 6 offerings from HSC with more likely to show up soon. First lets start with the similarities, namely the bearings. The HSC bottom brackets (all except 1) include ceramic hybrid bearings as stock, but all are available with full ceramic bearings. The stock bearing races are made of high chrome bearing steel, the balls of silicone nitride (Si3N4) with light contact seals and specially formulated ceramic bearing grease, for bearing that rolls buttery smooth.
Starting with the traditional External, (threaded) Bottom bracket. This is available in 2 flavors. BSA English threaded. 1.37×24 for 68mm shells. This fit is the standard bottom bracket dimensions. Alloy cups, ceramic bearings and a delrin sealing sleeve. It also comes in an Italian thread 36×24 for 70mm shells. Both versions come in a range of colors. The cups and bearings are outboard of the frame just the same as current Campagnolo/Shimano. The bottom bracket works with 2 piece cranks from Shimano and Campagnolo. Add the included Sram shim and it works with Sram, Truvativ and Bontrager as well. Almost any crank with a 24mm spindle (except FSA.) will work with this bb. This bottom bracket comes in Black, Blue, Gold, Green, Red, and Silver. Weight 87grams.
BB30. This open platform bottom bracket has been around for quite a few years but has only had interest from manufacturers in the last few years. Some of the frames that use BB30 are Cannondale and Parlee Z5. The BB30 is for both road and mtb having shell widths of Road 68mm or Mtn 68/73mm. On a bb30 system the bearings are pressed directly into the shell on the frame and held in place by a circlip on each side. A wave washer is used to help with any tolerance issues in the fit. The bearing that is used in BB30 is 6806 with a 30mm inner diameter and a 42mm outer diameter. It’s important to remember that just because a crank has a 30mm spindle, ie Thm, Ax, Lightning, etc… that it is not necessarily a bb30 crank. Many of these 30mm spindled cranks are built for 6806 bearings that are outboard of a 68mm shell with an actual width of around 86mm. So these cranks cannot go straight into a bb30 without some sort of adapter. Weight 54grams.
Press Fit BB42, (BB30 Adapter) Since we already looked at BB30 it makes sense to look at their adapters next. The bb42 is a bb30 adapter. Think of it as a traditional outboard bearing bottom bracket that presses in instead of threading in. The OD of the cup is 42mm so that it presses right into a BB30. The ID of the bearing in the cup is 24mm so it works with standard Shimano Hollowtech cranks. The bearings sit outboard making the effective width 90mm which is what Shimano and Campag UT cranks require. This does not require you to first have a BB30 bearing kit installed on your bb30 frame, the bearings are part of the adapter. The weight is 89 grams. So if you have a BB30 frame without bearings already installed and want to run a Shimano crank this is the adapter for you.
BB30 Adapters without bearings. These are once again another bb30 adapter, but this time without bearings. These are made of delrin and have a weight of 45grams. These also adapt a bb30 to work with Shimano road Hollowtech cranks. These require a bb30 bearing kit to already be installed in the frame. These then fit into the existing 6806 bearings that are in the frame. By doing that they reduce the ID of the bearing to 24mm and increase the shell width again to 90 mm.
PF30, Press Fit 30. PF30 is a refinement of bb30. Bb30 has a couple of potential short comings. You can damage your frame if you press a bearing crooked and they may sometimes suffer from creaking noises from the bearing/frame interface. Press fit 30 uses a regular bb30 crankset. Where PF30 varies is in it’s installation. Whereas bb30 has the bearing press directly into the frame, pf30 has a cup between the bearing and the frame. This means that the bottom bracket shell on the frame has to be even larger than a bb30 shell. While PF30 does use the same 6806 bearing when you account for the cup the OD of the bottom bracket and the ID of the frame need to be 46mm as opposed to the 42mm of bb30. Like bb30, pf30 uses a 30mm spindled crank and 68mm shell width. The delrin cups however do prevent damage to the frame from an improper installation and do better as resisting creaking noises.
BB86 Similar in design to pf30 but with a smaller ID. BB86 is basically a modified Shimano fit. It’s designed to work with Shimano Hollowtech cranks. BB86 keeps the bearings where they would be on a threaded outboard bearing bottom bracket and extend the frame shell out so that the bearings are not press fit rather than threaded. The bearings ride in a delrin cup which presses into the frame like a pf30 bb but has a cup OD and frame ID of 41mm.
There of course are other standards which are worth mentioning(BBright, 386EVO, BB90) but I won’t go into detail about those right now, we’ll save it for later.