Advice please (getting the rear wheel to run straight)

CRAIG#2 · Post by **CRAIG#2** » May 26th, '06, 20:28

I had to adjust the chain on my bike for the first time the other day. I used the markers on the swingarm to get the rear wheel true, but it doesn't seem right. The chain is making an odd clicking noise which it never did before and the wheel looks like it pointing slightly to the right hand side of the bike. I've been told not to always trust the markers on the swing arm! So what is the best way of measuring that the wheel is running true?

Webber · Post by **Webber** » May 26th, '06, 20:35

the markers will be fine just make sure everything is even, the clickin could be cos you have over tightened it or its to slack, should be around 2.5cm of play on the tightest spot of your chain, hope this helps, cheers.....Rich

Jay · Post by **Jay** » May 26th, '06, 20:42

as what Rich has just said, but when adjusting the chain, get the chain so its not too tight as when you tighten up the Wheel nut it tends to tighten the chain again!! so that may be your problem.....

Jay

Webber · Post by **Webber** » May 26th, '06, 20:52

yeah right, when i tighten my chain, when the nut is loose i adjust it so theres about 40mm of play cos when i do the nut up its around 25mm, good point.

rnblade · Post by **rnblade** » May 26th, '06, 22:52

the clicking may be a link that might be sicking or not pivoting correctly as it moves over the sprockets, give it a thorough once over to make sure they move freely.

Jimbo · Post by **Jimbo** » Jun 4th, '06, 21:12

The swingarm markers are NOT to be trusted!

The only way to check for sure is with a long (10 foot) piece of string and a mate. Wrap the middle of the string around the back of the rear wheel once and put the bike in gear so the wheel doesn; move (on a paddock stand as well).

run the 2 ends of the string to the front of the bike, one either side of the front wheel. now move the string in towards the front wheel until your mate tells you that they are touching the edge of the front of the rear wheel. (and therefore showing you where the front wheel is pointing) if they are an equal distance from the front wheel on either side, then your wheels are in line, if not, adjust the chain and retest until the back wheel is pointing straight.

Hope this makes sense!

J

age · Post by **age** » Jun 4th, '06, 21:17

there ya go jimbo I have changed your spelling for ya

Post by **TLS-Moose** » Jun 4th, '06, 21:20

What Jimbo said

..... or rather than string, use a good solid straight edge - steel or ally angle or box will do nicely, plank of wood only if you check down the edge to see it's straight first .....

Funky · Post by **Funky** » Jun 4th, '06, 21:25

Try using a laser pen, not so much hassle

Jimbo · Post by **Jimbo** » Jun 5th, '06, 20:30

Cheers Age!

Good Idea Moose..

not so easy to fit in a tool box though!

Post by **TLS-Moose** » Jun 5th, '06, 22:12

Jimbo wrote:Cheers Age!

Good Idea Moose..

not so easy to fit in a tool box though!

Why would it need to

The only place I ever need to worry about physical set-up of the bike is when putting it back together in the garage .... it's not like you need to carry it around with you is it

andrew · Post by **andrew** » Jun 6th, '06, 07:04

Jimbo wrote:The swingarm markers are NOT to be trusted!

The only way to check for sure is with a long (10 foot) piece of string and a mate. Wrap the middle of the string around the back of the rear wheel once and put the bike in gear so the wheel doesn; move (on a paddock stand as well).

run the 2 ends of the string to the front of the bike, one either side of the front wheel. now move the string in towards the front wheel until your mate tells you that they are touching the edge of the front of the rear wheel. (and therefore showing you where the front wheel is pointing) if they are an equal distance from the front wheel on either side, then your wheels are in line, if not, adjust the chain and retest until the back wheel is pointing straight.

Hope this makes sense!

J

bloody hell thats a lot of hassle to go to. i've never had to do this when adjusting a chain in my experience most swing arm markers are fine, however if you are having problems why don't u just take a measurement to the end of the swingarm (i.e. from the centr of your axle bolt) on both sides and make sure they are the same. Have to say tho your problem is far more likely to be that you've adjusted it incorrectly (look in your manual for correct slack but should be somewhere between 25-35mm for most bikes) or that u have a tight spot.

Post by **TLS-Moose** » Jun 6th, '06, 08:31

andrew wrote: ...............[Censored] hell thats a lot of hassle to go to....................... however if you are having problems why don't u just take a measurement to the end of the swingarm (i.e. from the centre of your axle bolt) on both sides and make sure they are the same............

The point is that a swing-arm is a fabricated part, usually of 3 principal sections - pivot, arm, and wheel spindle carrier - welded together. There are invariably production tolerances and this can mean that one side of the swing-arm is effectively longer than the other. Especially bearing in mind the asymetrical nature of most modern swingarms necessary to accomodate wide tyres. To measure from the end back in, as you say, will not solve anything. you would have to measure from the pivot axle back.

It is not uncommon for big-money race teams to strip down a brand new bike and put the chassis in a motoliner jig to "straighten" it before it has ever turned a wheel. It is inevitable in a bulk production process that there are tolerances - say 0.5% or so ..... in a swingarm 450mm long that 2-3mm at the spindle centres ......

A 17" wheel carrying a 190 tyre, 1mm out of alignment on the spindle will be nearer 2mm+ out of line at the crown ....

chris_1127 · Post by **chris_1127** » Jun 6th, '06, 08:40

i personally wouldnt trust the markers to intially set up the wheel - rather use a straight edge in the first instance, but once you've got it running straight, as long as you give each side exactly the same number of turns when you adjust it you wont need to do it again

Jimbo · Post by **Jimbo** » Jun 7th, '06, 21:50

[Censored] hell thats a lot of hassle to go to. i've never had to do this when adjusting a chain in my experience most swing arm markers are fine, however if you are having problems why don't u just take a measurement to the end of the swingarm (i.e. from the centr of your axle bolt) on both sides and make sure they are the same. Have to say tho your problem is far more likely to be that you've adjusted it incorrectly (look in your manual for correct slack but should be somewhere between 25-35mm for most bikes) or that u have a tight spot.

it is, but every race team worth it's salt I know of does it.. like moose says, it's only a fabbed part at the end of the day.[/quote]