Fnhon DB12: Ascent Revolution BB

While modifying the Fnhon folding bike to a 12 speed drivetrain, I took the chance to swap the bottom bracket as well. Not that the existing SM-BBR60 bottom bracket had any problems, but because I wanted to try the new bottom bracket by Ascent Bikes.

Special packaging! Very premium looking design.

This is for Shimano type of Hollowtech cranksets, which uses a 24 mm spindle diameter, and 68 mm wide, English threaded bottom bracket shells.

Full aluminium construction, where the left and right adapters are mated to each other for better concentricity control. It comes with a 1 mm spindle spacer in case you need it.

Designed in Singapore! The center cover extends out from one side of the adapter, instead of being a separate plastic piece like on Shimano bottom brackets.

Bearing dust cap on the side of the bottom bracket.

The left and right adapters are mated together during assembly, which helps to align the left and right side.

Since the threads on the left and right side of the frame are machined separately, there will be some tilt or concentricity error between the left and right side. Also, the faces of the bottom bracket shell may not be completely parallel to each other, causing the adapters to tilt slightly once fully tightened.

If the left and right adapters are not completely concentric to each other, there will be some imbalance and resistance to rotation, once the crank spindle is inserted. If the deviation is big, there will be extra friction and possibly lower bearing life.

This Ascent Revolution Bottom Bracket is designed to solve this issue, by using an extended center shaft to join the left and right side adapters together. This ensures that the concentricity error, if any, will be mitigated by the shaft alignment. However, in actual practice, if the deviation is so much that the shaft is needed to align them, it might not even be possible to assemble the bottom bracket, since the two halves will not be able to slot into each other.

Once fully tightened, I am not sure if the adapter position will be determined by the mating of this shaft, or will it be determined by the outside faces of the bottom bracket shell. I think it will help to a certain extent, especially if the outside face of the bottom bracket shell is poorly faced, like I encountered on the Brompton.

Bottom bracket weighs 111 grams, a noticeable increase over the BBR60 bottom bracket which weighs 76 grams.

During installation, the non-drive side bearing dust cap got pushed out by the crank spindle. Not a big problem as it can just be pushed back in.

New bottom bracket installed! No spacers needed under the bottom bracket, as the chain line is OK.

The benefit of this bottom bracket is smoother crank rotation, due to better bearing alignment and smoother bearings. I did find that the rotation is smoother than the BBR60 bottom bracket, but it is not buttery smooth like ceramic bearings.

Video showing the Ascent Revolution bottom bracket in action.

The BBR60 bottom bracket was only able to spin about 1-2 rounds in stock condition, so this Ascent Revolution bottom bracket is an improvement as it can spin 6 rounds.

I would say it is an upgrade over the BBR60 bottom bracket, due to the improved rigidity and also smoother rotation. However, it is not a day and night difference, like if I changed to a super high end ceramic bottom bracket where the cranks just keep spinning for more than 10 rounds.