Recently joined the forum. Just acquired 2 bike wife's is a gazelle grenoble 2020 7 speed nexus its like new. She's very pleased with it. Mines a kalkhoff agattu 2018 8 speed nexus with gates belt drive. The seat post which is supension is a fixed height. I was on tip top. So nipped off 3 cm of the frame to drop tbe seat. Easy job. I then tipped the bike upside down to get any alloy swarf out. Not knowing if the frame was hollow or sealed. A small amount came out OK. I banged the frame sides and where the pedals are to my amazement about 2 large cupful of find sand came out some in chunks it also came out near the pedals. I removed the Allen bolts on the pedals but couldn't work out how to remove the pedals to get the motor side cases off as sand was coming out everywhere? Banged until no more came out. Motor and pedals seem fine. Was this sand left inside when the frame was made , assuming it was cast. ? Should I strip the pedals, motor case to clear all of it? I know the motors are dear. I can only conure the bike hasn't been ridden on sand to fill the frame or am I wrong? Mystery?

Recently joined the forum. Just acquired 2 bike wife's is a gazelle grenoble 2020 7 speed nexus its like new. She's very pleased with it. Mines a kalkhoff agattu 2018 8 speed nexus with gates belt drive. The seat post which is supension is a fixed height. I was on tip top. So nipped off 3 cm of the frame to drop tbe seat. Easy job. I then tipped the bike upside down to get any alloy swarf out. Not knowing if the frame was hollow or sealed. A small amount came out OK. I banged the frame sides and where the pedals are to my amazement about 2 large cupful of find sand came out some in chunks it also came out near the pedals. I removed the Allen bolts on the pedals but couldn't work out how to remove the pedals to get the motor side cases off as sand was coming out everywhere? Banged until no more came out. Motor and pedals seem fine. Was this sand left inside when the frame was made , assuming it was cast. ? Should I strip the pedals, motor case to clear all of it? I know the motors are dear. I can only conure the bike hasn't been ridden on sand to fill the frame or am I wrong? Mystery?

It may be a bike made on a bending machine, and some of them use sand to stop damaging the metal pipe work, while bending.

But usually, all the sand would be removed or shaken out.

Maybe it also got welded after bending, and the heat caused the sand to stick together. Possibly an indication of dirty sand!

Just a thought.

Andy