Next, I tried to install the road caliper brakes onto the frame and fork, but ran into problems. Although there is no problem mounting the brake caliper onto the bike, the brake pads cannot reach the rims of the wheels! These are standard Dura-Ace 9000 brake calipers, so there should be no issue unless there is some problem with the frame.
Quite a big clearance between the front caliper brake and the tire
Even when the brake pad is shifted all the way down to the lowest point, it still cannot completely clear the tires
Same for the rear, the brake pad cannot clear the tire completely
As you can see, there is quite a big gap between the rear caliper brake and rear tire
I actually contacted the bike frame seller from Taobao via WeChat, but we were unable to resolve the problem. He told me that his other bikes are able to fit standard Ultegra brake calipers, although the brake pad holder has to be right at the bottom of the slot, at the limit. Dura-Ace and Ultegra brake calipers have similar dimensions, so I am not sure why it does not fit.
The factors affecting this are:
1) Brake caliper reach
2) Position of brake mounting point on frame, relative to wheel dropouts
3) Diameter of braking track on wheel rims
4) Width of rims or thickness of brake pads (small effect)
It seems to be that the frame dimensions are right at the limit where the brake pad is just unable to reach the rims properly. Almost there but not quite there, it is short by only 1 to 2 mm.
Actually this is easy to solve, I just need to use brake pad extenders, like what I used on the Dahon Boardwalk or Dahon Vitesse when I used road caliper brakes on those frames.
Aican brake pad extenders, which lowers the brake pads by about 10mm.
Weight of Dura-Ace 9000 brake pad holder and mounting hardware which is super lightweight at only 9 grams. Think it uses a titanium bolt and aluminium washers.
Aican brake pad holder, slightly heavier at 12 grams
Weight of hardware from Dura-Ace brake pad holder
Weight of hardware from Aican brake pad holder
If I combine the Aican brake pad holder with the Dura-Ace hardware, it is also lightweight at 10 grams
Testing the Aican brake pad holder with Dura-Ace hardware on the brake caliper
With the brake pad extender, the reach of the brakes is sufficient to reach the rims. However, what I don't like about the Aican brake pad holder is that the rounded area for adjusting the angle of the brake pad does not really work. Upon tightening the bolt, the brake shoe will be tilted to one side, no matter how I adjust it prior to tightening. Also, the squarish design is not nice looking, and it extends too much.
I found another type of brake pad extender by Ridea, which lowers the brake pad by 6.5mm instead of 10mm. Best of all, it has its own lightweight hardware which is also titanium. Although they are pricey, it should be worth the money.
Ridea brake pad extender which lowers the brake pad by 6.5mm. Looks much better than the Aican type, and also comes with its own brake pad.
Weight of Ridea brake pad extender is 10 grams. Slightly heavier than the Dura-Ace type, probably due to a bit more material from the extension.
However, there is one downside to this change, as I am unable to fit the SwissStop brake pads into the Ridea brake pad holders. There is some difference in dimension which makes it too tight to fit. I also cannot fit the Shimano brake pads into the Ridea brake pad holder.
Therefore, I have to use the Ridea brake pads, which at least seem to be of decent quality. Hope it works well with decent stopping power. Pictures will be shown later when the full bike is completed.
Finally, with the insufficient brake caliper reach issue resolved, I can move on to install the rest of the components onto the bike!