I purchased a used postie bike a while ago, and have just got around to improving the gearing. It was 32:22 with a 5 speed SRAM P5 hub, and I would spin out at 25 km/h. So I picked up a bigger chainring and new single speed chain.
However, the original chain is an order of magnitude beefier than the new single-speed chain.
On top is a spare chunk of 10 speed chain.
Middle is my new single speed chain.
And bottom shows the original chain.
Clearly it is all half-inch pitch bicycle chain, but the difference comes in the widths:
Measurements:
| Measurement | Original Chunky chain (used) | Single speed Chain (new) |
|---|---|---|
| Inner plate Inner Width | 3.55 mm | 3.60 mm |
| Outer plate Inner Width | 6.95 mm | 5.30 mm |
| Inner plate Outer Width | 6.60 mm | 5.15 mm |
| Outer plate Outer Width | 10.00 mm | 7.70 mm |
| Roller OD | 7.55mm | 7.60 mm |
So it is clearly Bicycle chain, not Motorbike chain.
The weight is significant too - Chunky chain is 530g and singlespeed is 320 grams. The original thick chain was too heavy for my "accurate" scales so had to be weighed with the Bike weighing luggage scales.
