BBR sprocket adapter bolts size and thread

[Otto Neumann]

Greetings,

Does anybody here know which Allen key size is required to undo the BBR CNC sprocket adapter's bolts?

I'm referring to the 3 bolts which holds the sprocket itself; as I'm moving from a chain drive to a belt drive, I've been trying to undo them, but a classic M5 Allen key will just spin inside the bolt, unless an M5.5 key is required, which I don't have, I suspect which the bolts may require a SAE Allen tool.

Should you know, could you also gently tell me if the bolts' threads are either metric, Whitworth, or of any other kind?

I'm planning to swap them, along with every other bolts on the bike, with Security Torx bolts, for extra safety against theft.

 

[ImpulseRocket]

Greetings,

Does anybody here know which Allen key size is required to undo the BBR CNC sprocket adapter's bolts?

I'm referring to the 3 bolts which holds the sprocket itself; as I'm moving from a chain drive to a belt drive, I've been trying to undo them, but a classic M5 Allen key will just spin inside the bolt, unless an M5.5 key is required, which I don't have, I suspect which the bolts may require a SAE Allen tool.

Should you know, could you also gently tell me if the bolts' threads are either metric, Whitworth, or of any other kind?

I'm planning to swap them, along with every other bolts on the bike, with Security Torx bolts, for extra safety against theft.

I don't know the size, but if it is not a metric 5.5 it will be a 7/32" standard key. They are within almost 2 thousandths of on another. 5.5mm = .2165 inch. 7/32 = .2188inch So if a 7/32 will fit, it's going to be rather snug if it is a 5.5mm

From what I have read on other threads, the bolts can actually be either. Not sure how true that is and I don't have one myself to size.

 

[Otto Neumann]

I don't know the size, but if it is not a metric 5.5 it will be a 7/32" standard key. They are within almost 2 thousandths of on another. 5.5mm = .2165 inch. 7/32 = .2188inch So if a 7/32 will fit, it's going to be rather snug if it is a 5.5mm

From what I have read on other threads, the bolts can actually be either. Not sure how true that is and I don't have one myself to size.

Thank you, under different conditions I would have snatched the angle grinder to cut a slot into the bolt heads, and call it a day, but if the threads may be non metric, I cannot risk to damage the bolts.

 

[Chainlube]

Thank you, under different conditions I would have snatched the angle grinder to cut a slot into the bolt heads, and call it a day, but if the threads are non metric, I cannot risk to damage the bolts.

The one good thing about using the grinder is you warm up the bolt as you put in the slot. Makes it easier to come out.

 

[Otto Neumann]

The one good thing about using the grinder is you warm up the bolt as you put in the slot. Makes it easier to come out.

I can confirm it was a 5.5mm wrench, I checked it out with the caliper, and I got away with a 7/32" allen key; the threads are a standard M10x1.25. Off they goes, and in Safety Torx bolts goes~

I can't wait to post the result, and update my Dell'Orto SHA post, it's going to probably be the first completely belt drive huasheng 49cc bicycle