In the earlier post, I shared some information about the new sealed bearings pivots for the Birdy. Now, I will be installing them onto the Birdy Fork, in an attempt to improve the front suspension smoothness of the Birdy AXS.
Previously I had already dismantled the Birdy front fork completely, so I am familiar with the structure. The stock pivots can be removed easily, so that is no problem.
Stock pivots on the Birdy front fork. Note that it has self-loosened, as it is only kept in place by Loctite.
One problem with the stock Birdy pivots is that due to the nature of the bushing construction, the tightness of the rotation torque is mainly dependent on how tightly you clamp the 2 halves of the pivot. If it is too tight, the whole joint is jammed and does not rotate. If too loose, there will be axial free play. Therefore, it is necessary to adjust the clamping such that there is minimal looseness. The pivot is only held in this orientation by liberal use of Loctite on the screw thread, as the pivot is not completely tightened in this condition.
Stock pivots removed from the fork.
This sealed needle bearing has to fit inside the fork.
Here are the outer plates of the pivot.
Sealed needle bearing will be pressed into the centre section of the pivots, into the stock plastic bushing.
Overall view of the new pivot. The 2 ends with shoulders will rest inside the outer plates, while the needle bearing will be inside the middle section. In this setup, the pivots can be fully tightened as it bottoms out against the ends of the sealed needle bearing in the middle.
It's quite a tight fit to ensure no radial looseness, so it cannot be pushed in by hand.
Using the bottom bracket press fit tool to help press in the new bearings.
Needle bearings installed after much work. At this point I thought of reverting to the stock pivots, but I'm already at the point of no return.
With one side of the pivot shaft installed. Note how the female part of the pivot (not shown) will rest inside this area of the fork.
The needle bearing is pressed into the centre section of the fork by press-fit. Any rotation will be between the inside of the needle bearing and the centre shaft of the titanium pivot.
The width of the fork legs don't really match up nicely, there is some offset which means poor pivot alignment.
One thing which I overlooked is the front hydraulic hose routing for the front brake caliper. The length and routing has to be precise, to prevent overbending or pulling on the hose during folding and unfolding.
Previously, the hose will slide over the flanges of the pivot, since the flanges are chamfered. However, this new titanium pivot has square shoulders, which tend to catch on the hose during folding and unfolding.
Hydraulic hose tends to catch on the shoulder of the pivot, so it needs to be adjusted manually during folding and unfolding.
Hydraulic hose is still routed the same way, on the inside of the front fork.
New Multi-S pivot installed
The pivots protrude more from the fork legs (both inwards and outwards) compared to the stock pivots. Not really an issue though.
Close up view of the new pivot.
Observations of the new pivot:
1) Square shoulder of the pivot catches on the front hydraulic hose during folding and unfolding.
2) Additional weight even with titanium parts, as stock pivot is aluminium.
3) Difficult installation with press fit tools required.
4) No improvement in stiction reduction due to misalignment of the fork legs.
5) Can tighten fully without jamming the pivot joint.
My verdict: Don't waste your money or your time installing the sealed bearing pivots. Due to the misalignment of the fork legs, there is no improvement in the smoothness of the pivot joints. Only benefit is that you can tighten the pivots with higher torque to prevent self-loosening, since the sealed bearing in the middle prevents the joint from being jammed.
Some pictures of the Birdy AXS below!
Along the Kallang Park Connector Network, watching the sunrise, with the National Indoor Stadium in the background.
With Marina Bay Sands and the Singapore Flyer in the background!
