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Discussion Starter #1
Hello

I need some help with my bike.

Some time back (in the winter) I bought a 749Drak. The bike was in a realy good condition (on the out side), except for some scratches on the rear swing arm. The seller said they were from the bike stand and I belived him.

So then the summer came and I started to ride the bike. When riding I noticed that the bike is pulling to the left. When I release the steering I have to lean to the right of the bike for it to go straight. This is apparent only at low speed, above 100km/h the bike goes fine.

At home I took the side panels off and inspected the frame. I didn´t find anything wrong with it. The front forks look ok too. So a suspect the rear swing arm. But form what i can see it doesn´t look to be any damege except the scratches.

Does anyone have any information why is this is happening and how to fix it?

Thank you.
 

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Have you checked to see if the chain adjusters are aligned? If one side is in or out more than the other it will throw off the rear tire and cause it to track one way or the other.
 

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Discussion Starter #3
Yes, a also thought this was the problem, because they were not aligned, there was aprox. 1mm diference. So I did this yesterday. I aligned them perfectly and it didn´t make any diference.

I starting to get concerned that I have a problem withe the frame. Is it posible that the frame is dammaged in a way that it woudnt make any problems at high speed?

Ther is also no vibration on the front wheal when driving, cornering.
 

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I'd double and tripple check the chain adjusters before even thinking that a few scratches on the swingarm would do it, it is possible but still kind of a long shot. Another long shot to check would be the forks. Are they both at the same height in the tripples? They could need a rebuild too. It is a long shot but if one is softer than the other it could pull to one side.
 

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tires

How are the tires ? These can give lots of clues to handling issues. Can you post some closeups of front and rear ?
 

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Discussion Starter #7
Did you align the rear wheel using the adjuster marks on the swingarm or by lining it up with the front wheel? Also, please post pics of the scratches.
I used the marks on the swingarm. Do you think that the marks are a little off?

I will take a picture of the scratches when I get home, because I have the bike in a garage where my parents live. But they are about 1mm thick, 0,5mm deep and 3cm long. Ther are about 4,5 of them. Do not know exact. Ther are on both sides of the swingarm.

BCT, I have checked the front forks, they do not look damaged and are working god. The commpresion and the rebound works god. Will check the height. I forgat to do that.

BTW, sorry for the bad English. :)
 

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Discussion Starter #8
So I convinced my brother to take some photos of the bikes rear swingarm and the front forks.

He took pic. only of the right side (sorry about that), but the scratches are almost the same on the left side.

There is also a photo of the rear tire, but it is not got. The wear is about equall on both sides.

I hope it will help you to help me solve this mistery.
 

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Chilehead
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Your rear tires is worn out, and needs to be replaced. Start there.

How is the front tire?

The only scratches I see are probably from using a rear stand, nothing to be concerned about.

Tom
 

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Agreed.

Yes the lines are not accurate...do the string method, and when you know it's right, mark the swingarm with new, accurate marks.

The xx9 bikes' chain adjustment hardware sucks.
 

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Also might check to see if the right & left clipons are adjusted differently (i.e. one is at a different angle than the other).
 

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The front end has rebound and compression in opposite shocks. I always thought this would be the case. But I was assured it couldn't be. See I dropped my bike on it's side and that cracked my yoke. I got a new yoke but some how while trying to screw with the front end (lowering and raising) I had twisted one of the shocks. Now this will effect the suspension because inside your twisting one spring up and not the other at the same rate. What needs to be done is to hang the bike buy the frame (or a pitbull stand that lifts at the bottom yoke), loosen all the front end bolts from the yoke down to the axle. Start at the axle and redo everything. Letting the forks lay in the clamps as they will.

There are people who can measure your bikes points and tell you if the frame is bent. They lay your bike on a table and measure specific points. This is done to race bikes after they have been crashed. You could most likely do this with a good rear stand and a plum bob for vertical and a laser for horizontal plane.
 

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Your rear tires is worn out, and needs to be replaced. Start there.

How is the front tire?

The only scratches I see are probably from using a rear stand, nothing to be concerned about.

Tom
I'm with Tom on the tire and the scratches. The rear tire is definitely toast which could cause the pull to one side, especially if the front is gone too.

Agreed.

Yes the lines are not accurate...do the string method, and when you know it's right, mark the swingarm with new, accurate marks.

The xx9 bikes' chain adjustment hardware sucks.
I like the Giles adjusters a lot more. Not sure if they are 100% accurate but anything is better than the stock one.
 

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Could be Brinelled Steering Head Bearings.

I ran into this a long time ago with a friends bike. When I was behind him he would always be sitting twisted on the thing. Looked weird. I road it one day and I had to do the same thing in order to keep it going straight, VERY uncomfortable.

What could be happening is the Brinelled Bearing Races are causing the rollers to fall into the “Dents” - usually left buy an impact. If the adjustment is/ was loose, the constant impacts will dent the races. They will want to fall into the dents easily and you keep having to pull them out in order to get the steering straight and it’s not something easily felt while riding.

It will most likely be the lower bearing race so in order to detect it weight will need to be on the front end. An easy way is to take 2 thin boards and put grease between them. Park your front tire on center and turn the bars. If you get a detent type of feel the bearings need replacement.
 

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Discussion Starter #15
Thank you for the info.

Today I will try to do the string method, and we will see what happens.

Hope it works. :)
 
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