Eccentric Bottom Bracket Instructions

Velo Orange Eccentric English Threaded Bottom Bracket

The Velo Orange Eccentric English Threaded Bottom Bracket is a great solution for converting your bike with an English threaded 68mm or 73mm bottom bracket shell and vertical or non-adjusting dropouts to a single speed, using 24mm spindle, 2-piece cranksets.

Construction: The shell is CNC’ed from single-piece alloy, and features a threaded base, with a concentrically-offset outer ring that houses the bearing, which is how this bearing is able to do its thing. You can see the construction by looking at the below exploded view of one side of the bearing:

The profile of the cups is identical to any number of English threaded/24mm standard bottom brackets on the market, so you could even run this BB on your geared bike while you aren’t using it as a chain tensioner on a single speed setup.

Compatibility: Please note that you are only able to use this bottom bracket with 24mm spindle, two piece cranksets, such as Shimano Hollowtech, FSA, RaceFace Aeffect, and Promax, to name a few. This bottom bracket is also compatible with SRAM GXP spindled cranksets, using a 1-mm thick sleeve that is supplied with the bb, but we’ll get to that in the instructions.

How it works: As pictured above, each cup is actually a two-part construction; there’s a cup, which threads into your bottom bracket shell, and is simply a symmetrical and centered chassis for the sleeve, and then there’s the sleeve, which does all the work. The sleeve houses your bearing, which is offset slightly from the centerpoint of the sleeve itself. 

By dialing out the small 2mm allen key grubscrews on the outer edge, the sleeve is allowed to rotate freely around the cup. As it rotates around the cup, you can see that the bearing actually rotates eccentrically, or offset, from the centerline of the cup. There is just enough room that the spindle is allowed to travel in a concentric circle, closer to the inner edge of the bottom bracket shell of your frame, which gives just enough tolerance for you to snug up a slightly loose chain. The grub screws thread inwards and tension the sleeve in place around the cup, which is what holds the whole assembly together, and keeps it from moving.

Directions:

• First verify that your frame and crankset are compatible with this product. See the information above and if you still aren’t sure, please reach out to us at info@velo-orange.com. We’d be happy to figure it out with you, and answer any questions you may have.

• Prep your frame, and the cups. Clean the threads on your frame’s BB shell, and apply a moderate amount of assembly/bearing grease on the threads of the shell and your new bottom bracket. Also ensure that the 3 grub screws on the outer edge of each sleeve are snug around the cup. These grub screws require a 2mm allen key, and are very low-torque (1.5Nm). DO NOT OVERTIGHTEN THESE SCREWS - Once stripped, they will be very difficult to remove, and may make your bottom bracket difficult to use as intended. Always make sure you’re using the correct size wrench, and that it is in good condition/won’t strip out the screws.

• Once the sleeves are snug on their cups, thread the cups into your frame by hand. English Threaded bottom bracket cups only thread in one way, so if it’s not going in easily, inspect your shell for thread damage, or test the other side to make sure you don’t have the cups backwards.

• You’ll note that every other corner of the edge of the sleeves has a bored hole, alternating the grub screws. These larger holes are designed for you to insert the end of your supplied VO Eccentric Bottom Bracket Installation Wrench (which also doubles as a lockring tool). Treat the sleeve as a standard BB cup, and use the tool as pictured to tighten the cup into the frame:

• Once both cups are greased and tightened in your frame, loosen all 6 grub screws, so that the sleeves rotate freely around the cup. You’ll notice that the bearing now moves eccentrically around the center of the bottom bracket shell. Orient both bearings to the same position on either side of the bottom bracket, and install your crankset. You may not need the supplied spacers for your application, but it will depend entirely on what shell width, and what type of crankset you are using. All cranksets will need the wave washer installed on the spindle attached to the arm before sliding through the bearings (this will be the driveside for 99% of cranks out there). Please follow all crank manufacturer’s directions for installation, if necessary. If you are using a SRAM GXP crankset, please see the “additional notes” section before proceeding.

• Now that the crankset is installed on your bearings, you should be able to rotate the sleeves of the bottom bracket in the same direction together, resulting in your crankset rotating slightly around the centerline of the shell. You’ll want to orient the crankset as far “backwards” (towards the rear dropouts) as possible. Install your chain, and cut it to the shortest length possible. Half Links are ok to use with our BB, so long as the chain you’re using is compatible with single speed usage.

• With the chain installed completely, rotate the sleeves in the same direction, forward (clockwise, counterclockwise doesn’t matter, so long as both cups follow the same path and don’t bind). This will result in the crankset being further forward than you started, and shorten the chain. Do this by hand until the chain tension doesn’t allow you to rotate any further forward. DO NOT USE THE INSTALLATION WRENCH AS A TENSIONING TOOL. Using the tool to tension the chain may result in uneven bearing wear and increased resistance to your cranks. 

• While holding the sleeves in place, use your 2mm allen key to snug up the grub screws, in a rotating pattern. Do not tighten one down all the way, then move on. Start by threading all three grub screws in until you feel resistance, then start rotating your tension, until you’ve properly torqued them down to 1.5Nm. Do the same for the other side.

• Install your cranks using the manufacturer's suggested installation instructions.

• Test your cranks spinning! They should feel smooth and silent, and your chain tension should be even throughout the crank rotation, unless you’ve got a slightly warped or loose cog or chainring.

Additional Notes:

• This crankset is compatible with SRAM GXP cranksets. The difference between this and other 24mm spindles is that the driveside bearing interface on the spinde is 24mm, while the non-driveside bearing interface is actually 22mm. This means that if you put a GXP through a standard 24mm symmetric bottom bracket, the non-driveside end of the spindle would be loose and knock around. We’ve supplied a 1mm-thick sleeve to fit inbetween the non-driveside spindle and the bearing. Note that the lip must be facing out for the sleeve to fit, as pictured:

• We offer replacement bearings for this bottom bracket, but if you were interested in upgrading your bearings to something with higher-quality construction, they share the same dimensions of #6805 bearings.