String method? Rear wheel alignment?

[lbk]

Ok, so I've heard of this "string method" for aligning the rear wheel. Can someone explain this to me? I used to always go by the marks and I know people say they can be off, but now I don't have marks to go by so I guess I have to figure this out. If someone could layout the steps I would greatly appreciate it.

[Jeff]

it's complicated.  You take the string, wrap it around the tire, stub your shins on the rearsets, break the string, start over, knock bike off the stand.  Fix your broken levers, wrap the string once more.  Give up, throw the string away and use the marks...

[251am]

 Gonna be at BHF this weekend? I'll show you a great way a Noob just taught me. It is incredibly fast and accurate.   

[lbk]

Gonna be at BHF this weekend? I'll show you a great way a Noob just taught me. It is incredibly fast and accurate.   

I will be at Blackhawk this weekend, pitted out by turn 6 red tanked Mille with white race plastics #724.

For now I did just use the marks.

[251am]

I will be at Blackhawk this weekend, pitted out by turn 6 red tanked Mille with white race plastics #724.

For now I did just use the marks.

  Cool, I'll come find you with the tool. You'll like it. A Mille? You run STwins?

[Woofentino Pugrossi]

Ok, so I've heard of this "string method" for aligning the rear wheel. Can someone explain this to me? I used to always go by the marks and I know people say they can be off, but now I don't have marks to go by so I guess I have to figure this out. If someone could layout the steps I would greatly appreciate it.

Dave its simple. You measure from the centre of the swingarm pivot to the centre of the rear axle. Should be the same on both sides. I've seen some peopel have a string tied to a wooden dowel rod thay can slide into teh swingarm pivot and have measurement marks on the string.

[andy342]

It's easier with two metal bars and a clamp.

I use 1 inch aluminum square tubes about 6 feet long.  Clamp the bars to each side of the rear tire. point the front wheel forward, and measure from the rim edge to the bar on each side.

The string method works the same way.  But if it's windy it's hopeless.

[Ridgeway]

I've used the string method.  The thing I like about it is that it aligns your rear wheel with the front wheel.  Most of the tools and gadgets I've seen are just checking to see that the sprockets are aligned with each other.  That doesn't guarantee that the bike tracks straight.

It is a PITA though and I don't do it often.  I like the metal bar idea though, might just have to rig something like that up.  If I'm changing gearing at the track and need to adjust the axle to accomodate, I'll usually just cheat and make sure I turn both adjusters the same amount.

[kngh557]

Maybe someone can answer this....How can the string method be accurate if the front wheel is a movable object...meaning how do you know if the steering is centered.  Would this not give a false reading?

[HAWK]

String should touch the rear wheel at front and rear (just BARELY, string should be perfectly straight, not bent at front of rear wheel), adjust the front wheel position so that the measurements are equal from the string to the rear of the front wheel on both sides and also equal from the string to the front of the front wheel on both sides if you can't get equal at both the front and rear of the front wheel then you are not aligned.

[superspud]

String should touch the rear wheel at front and rear (just BARELY, string should be perfectly straight, not bent at front of rear wheel), adjust the front wheel position so that the measurements are equal from the string to the rear of the front wheel on both sides and also equal from the string to the front of the front wheel on both sides if you can't get equal at both the front and rear of the front wheel then you are not aligned.

Do people actually do this?  I usually just do what Jeff said, use the marks.  And as far as I can tell my bike still goes straight most of the time; even sometimes in T7 and T1 when it's not supposed to.  

[L8brake731]

Depending on what your alignment objective is; there is a tool available to align the REAR wheel in perspective to the engine. All things being equal (and square), the tool clamps to the your rear sprocket with the chain on it and has about a 8" guide that floats directly over the the top of your chain. This is a VISUAL guide and can give you an indication if the rear wheel is square, relative to the counter shaft sprocket and engine.
I'm sure you can make one of these up using a hobbie type "C" clamp and a HD piece of stainless (of course!) welding rod.
Until then, the best method is the tape measure from center of swing arm pivot to rear axle pivot.

[251am]

Do people actually do this?  I usually just do what Jeff said, use the marks.  And as far as I can tell my bike still goes straight most of the time; even sometimes in T7 and T1 when it's not supposed to.  

  Only AFTER I've found my parking spot though....in the grass...

[Team_Serpent]

The system I use can be seen here http://www.laser-lines.com

Reasonably priced, quick, easy accurate.

Read the whole home page to understand why rear to front alignment is so important.

[superspud]

The system I use can be seen here http://www.laser-lines.com

Reasonably priced,

What is the cost and do they have any distributors?

[Team_Serpent]

What is the cost and do they have any distributors?

I think they have distributors but I'm not sure.  There is a link at the bottom of the home page for ordering -  I clicked on it and the price was $188.00

I brought mine a couple of years ago directly from the guy who owns the company when he was at the WERA GNF doing demos.

[Protein Filled]

You can buy it on the website. It said $188.00

[ecumike]

So for those of you who do all these measurements, instead of just making sure you turn the left one the same amount as you turn the right one, when you switch gearing.... how accurate do you be?.. I find it hard that it would be very accurate measuring from the "center of the swingarm pivot" w/o something solid in there keeping the tape measure place.

As well, if your rear wheel spins very freely, is that safe to say that it's aligned just fine?..  I would think that a rear wheel that's not aligned would cause the chain to rub 'more'/have more friction on the rear sprocket (b/c the sprocket is attached to the wheel/axel and it's not aligned at the same angle as the front sprocket) and would not allow the rear wheel to spin as much.  Thoughts?

[Protein Filled]

Here is an article written by Rob Tuluie, the creator of the Tularis, regarding chassis alignment that may help:


http://motorcycle.com/mo/mcnuts/chassis2.html

and

http://www.motorcycle.com/mo/mcnuts/chassis.html

[L8brake731]

Wow! LASER LINES....why didn't anyone else think of that? What a GREAT idea Let's hope your rims are absolutely true, I'm sure they make you check them 180 out to make sure but that's a l-o-n-g way from the axle, other hard parts and too rim dependent, no? What happened to the "marks on the swing arm topic"?

[Team_Serpent]

So for those of you who do all these measurements, instead of just making sure you turn the left one the same amount as you turn the right one, when you switch gearing.... how accurate do you be?..

I only use the laser alignment tool once in a while after initial set-up - say once every other race weekend to make sure I haven't turned one adjuster further than the other during gearing changes or after a crash to make sure the bike isn't bent. It's very accurate, I've tested it against the same measurement plane using a Computrack System.

I find it hard that it would be very accurate measuring from the "center of the swingarm pivot" w/o something solid in there keeping the tape measure place.

To be perfectly accurate when measuring these points you do need special tools/equipment.

As well, if your rear wheel spins very freely, is that safe to say that it's aligned just fine?..  I would think that a rear wheel that's not aligned would cause the chain to rub 'more'/have more friction on the rear sprocket (b/c the sprocket is attached to the wheel/axle and it's not aligned at the same angle as the front sprocket) and would not allow the rear wheel to spin as much.  Thoughts? /quote]

There is a lot of play/tolerance between chain and sprocket so you could be miss-aligned and still have what appears to be fairly good free spin when testing by hand. But you're right - miss-alignment = friction which = decrease in performance.

[Team_Serpent]

Wow! LASER LINES....why didn't anyone else think of that? What a GREAT idea Let's hope your rims are absolutely true, I'm sure they make you check them 180 out to make sure but that's a l-o-n-g way from the axle, other hard parts and too rim dependent, no? What happened to the "marks on the swing arm topic"?

lbk first asked about the string measurement process that has been around for years. Laser Lines is quicker, easier and more accurate.  Is it the end all be all, most accurate measuring device available? No. But from my experience it's pretty damn accurate.

I think the "marks on the swingarm" topic died when most everyone figured out that they are not very accurate 99.9% of the time.

Most people posting are trying to help with information about alignment points - your post seems to be kinda sarcastic and argumentative. Maybe I miss-read and took it the wrong way - don't want to argue, just trying to help.

[L8brake731]

No argument. Just stating that there exists too many variables to use a (what is a wheel mounted) device to check alignment (true) that takes the beating a wheel does.
I'd say the best investment is to have GMD Computrack do it once and then go from there. After re-reading the post, I'm sure he's got it figured out.