Hitchcocks Forum

DUFFEL WITH ANOTHER QUERY THAT'S PUZZLED ME FOR YEARS WHEN ADJUSTING CHAINS YOU ALWAYS CHECK AND ADJUST AT THE TIGHT SPOT OWING TO WEAR IN CHAINS AND SPROCKETS ETC I HAVE JUST RENEWED THE REAR CHAIN WITH A GOOD MAKE PUT A NEW GEAR BOX SPROCKET ON ENGLISH MADE SUPPLIED BY OUR HOST WHO ALSO SUPPLIED AN EXCHANGED BRAKE DRUM/SPROCKET WHICH HAS HAD THE OLD SPROCKET TEETH MACHINED OFF AND A NEW BOLT ON SPROCKET. WITH THE NEW CHAIN AND SPROCKETS FITTED I WOULD HAVE THOUGHT THAT THERE WILL BE VERY LITTLE DIFFERENCES IN THE TENSION ALL ROUND BUT THERE ARE TWO PLACES IN THE CHAIN THAT HAS A TIGHT SPOT AND WHEN THESE ARE SET CORRECT THE REST OF THE CHAIN IS TOO SLACK ?

Are you sitting on the bike and having somebody check the slack, otherwise with it sitting on the centre stand about 40mm slack is about right. Slack is much better than tight, remember the swing arm lengthens whan you go over a bump

And we are only fitting "O" ring chains out here now, everybody is getting sick of this chain adjusting rubbish with cheap chains

Hi Duffel,

If both chain sprockets were perfectly round and concentric with their respective axes, there would be no "tight spots. However, machining tolerances, worn tools mean that perfection is rarely achieved, hence possible tight spots. However, if the difference between tight and slack is say 25 to 40mm, then the variance is +/- 7.5mm.
Compared to the distance from the rear axle to the mid point of the chain, approx. 280mm on my EFI, then the change of effective length this 7.5mm represents is minute (using root of sum of the squares principle) and works out as 0.1mm. Not worth worrying about IMHO.

Cheers TrevorCH

Thanks Tevorch and NORM I do usually check and adjust chains with somebody sat on the bike but as this bike has a fully enclosed chain guard it is a bit difficult to check adjustment properly as slightly out of line or slackness and backlash it rubs the inside the cases so I had it on the stand to check the difference in the tight and slack and adjusted the best I can I then put a mark on the Snail Cams as I had to remove the hub and chain to replace the chain cases with the wheel and hub replaced to the marks I will get some one to sit on it for final adjustment