Suspension settings

[HelmetHair]

took @ for MOT-passed, but he mentioned loose chain, and said "it must be set on centre stand"
usual chat about @ chain/output shaft followed.
he then pointed out the suspension on my bike being loose, due to an old worn spring.
he says there is so much "up travel" (my words) that if i was riding and the back wheel dropped down (eg a pothole, a road hump at speed) the chain would slack off even more and could come off the rear sprocket.
I think he had a point, so tightened up my spring on the adjuster nut, and then re-set the chain slack
the net result is that I have a harder suspension setting, with less "up travel" (that is, with the bike at rest on the side stand I can lift it up about 3 inches instead of 6 before it reaches the top of its travel and the rear wheel comes off hte floor). the chain had to be tightened considerably to the correct 40mm slack on the side stand.
the bike rides fine, and I am happy that the chain doesn't overtighten with 160kg (me and the wife) on it, but also can not "overslacken" if i am riding alone and the back end falls down a pothole (or braking heavily etc)

Have I done good or bad? How much "uptravel" is there in a new @ or an old one with a new spring/shock?
any comments welcomed!

[Pussyhorse]

I'm confused. You said you had the normal chat about AT chain tension, and then set it to 40 mm anyway. That's waaay too tight.

As for the suspension, can't help you there. Mine is set to 'tired & wallowy'.

[HelmetHair]

yup, 40mm, as per the sticker on the rear arm, and the manual.

is this making sense, though? I have never considered the suspension settings in relation to the chain slackness before!
(perhaps because I'm thick

[BobA]

I think the "Up Travel" you may be mentioning is referred to as "Sag".

Sag is the free play in the shock before the spring starts to do it's work. As far as I know, all bikes should have an element of sag in the suspension (especially sports bikes).

Let us know what model AT you have and someone will give you a measurement I'm sure.

Bob

[HelmetHair]

I have the RD07A.
Thanks!

[BobA]

Incidentally, there are some good guides on chain adjustment, but I tend to errr on the side of caution and have it "looose and lubed" (the chain that is!!!)

Check this guide for help.

http://www.atic.org/faq/chain.html


Hope that helps


Bob

[BobA]

I'm an RD04 blokey, so can't help with that measurement, SORRY!

I'm sure someone will offer their help and vital statistics (of their bike!!)

Bob

[Lord Stig]

yup, 40mm, as per the sticker on the rear arm, and the manual.

is this making sense, though? I have never considered the suspension settings in relation to the chain slackness before!
(perhaps because I'm thick

Yes - the more the suspension 'sags', the tighter the chain gets. If you have a lot of weight on there and then compress the suspension (say, over a pot hole) the chain will tighten - hence you need slacker still when you carry more weight. The reason is the arc of the swing arm, and the problem is worse on our sort of bikes than it is on sports bikes because of the suspension travel (= wider arc of the swinging arm). That's why sports bikes have such small chain slack specifications. The harder you make your suspension by increasing preload, the less the swing arm will swing upwards for any given load, and the looser the chain will be when the bike is upright.

Probably you knew all that and I've misunderstood - sorry if so!

Stig

[HelmetHair]

how many links should an @ chain have?

[Lord Stig]

124 I think...

Stig