Chain Tensioner

[Covboy]

Hi

Probably a numpty question, but I don't know the answer...

With a modern upper chain tensioner ( for example the Gran Turismo one, as pull down) is it necessary /desirable / preferable to fit the original lower chain guide?

[Warkton Tornado No.1]

There’s probably more qualified reasoning than mine, but I’ll start the ball rolling & read any other responses you get.

IMHO the original intention of the lower chain guide serves the purpose of ‘confining’ the chain, particularly if it is too slack, so that it doesn’t whip about too much & damage the crankcase.

However, with the advent of racing where upper chain guides were developed to be far stronger & durable, the function of the lower chain guide has become largely redundant.

If you think about the area where the chain has slack, it will be on the top whilst the motor is pulling the chain around. That situation is reversed when the motor is off throttle & coasting or braking. The slack in the chain will then be @ the bottom with the upper chain guide under load.

Circuit racing, with the hard braking using whatever is available to slow down, like ‘engine braking,’ places a tremendous load on the upper guide, which was why the standard products used to collapse so readily.

If you understand my reasoning, you might agree it’s not just alright, but better, to leave out the lower chain guide completely.....

[Covboy]

Thank you for the quick reply