Forced chain shortening to s/speed problem

[Kranswurm]

Mate had a branch jump up and attack his rear derailleur y/day.

Removed the fooked part and had to turn the bike into a single speed to get home.

Picked the middle chain ring up front and middle on the cassette and cut and joined the chain.

However,the chain kept riding up the cassette and making the chain so tight it broke.

What is the answer to this guys for future mishaps

[Tumbleweed]

make the chain tighter so it resists the "jump" teeth?

[Kranswurm]

Yeah,although we tried to make it fairly tight.

I thought maybe put it on the biggest cog at the back so its got nowhere to go,then a bakkie came past and  we gave up

[Johan Bornman]

Mate had a branch jump up and attack his rear derailleur y/day.

Removed the fooked part and had to turn the bike into a single speed to get home.

Picked the middle chain ring up front and middle on the cassette and cut and joined the chain.

However' date='the chain kept riding up the cassette and making the chain so tight it broke.

What is the answer to this guys for future mishaps

[/quote']

 

It is most probably 'cause the chainline wasn't good and the chain then defaulted to correct the chainline and the default was unfortunately a larger sprocket rather than a smaller one.

 

Can you remember what gear you started off in, front and back please?

[Thug]

We almost had exactly the same problem on a Breedtsnek ride last year but managed to get back to the cars before the chain the chain snapped.

 

 

 

[Kranswurm]

Mate had a branch jump up and attack his rear derailleur y/day.

Removed the fooked part and had to turn the bike into a single speed to get home.

Picked the middle chain ring up front and middle on the cassette and cut and joined the chain.

However' date='the chain kept riding up the cassette and making the chain so tight it broke.

What is the answer to this guys for future mishaps

[/quote']

 

It is most probably 'cause the chainline wasn't good and the chain then defaulted to correct the chainline and the default was unfortunately a larger sprocket rather than a smaller one.

 

Can you remember what gear you started off in, front and back please?

 

Hi JB

It was the middle ring up front and the middle back.Not sure of which gear at the back but the line seemed straight.

[Johan Bornman]

Hi JB

It was the middle ring up front and the middle back.Not sure of which gear at the back but the line seemed straight.

 

I am intrigued. If you still have access to the bike, could you please lay a straight edge of sorts along the chain and see just how good or bad that chainline was?

 

I know that belts running on variable (conical) pulleys will always default to the major diameter. I can't figure out how a chain will do this but we'll get to the bottom of this somehow.

 

Perhaps you want to donate that bike to science?

[Kranswurm]

Ha ha!

Its not my bike and I believe its gone to hospital today.

Feel sorry for the guy.Brand new first ride.

[Nuffy]

I had a similar thing happen to me once. Luckily it never broke, but it did make removing the back wheel and the chain very difficult. I think the chain wasn't quite tight enough to hold it properly in place, and with a little bump it caught the teeth of the next sprocket up. I think as long as there is a larger sprocket there, flex in the chain and bumping and moving around will mean there is always the posibility of it moving to the side just enough to catch a tooth of the next sprocket, and then it'll just get pulled up.