Bike pulls to the left, why?

Alcdrew

Senior Member
Location
UK
OK bit of back ground... I crashed my bike a couple of weeks ago, crumpled the front wheel and also caused the disc brake to warp, and a few brusies to me:sad: I have puchased a new wheel and disc, but now my bike has a pull to the left, bit like if your traking on your car is out.

So my question is, what have I done? Is there some way of checking maybe the forks slightly bent? or the frame:ohmy: or something a lot more simpler? Problem is I'm a bit poor at the moment and can't really afford to take it to the LBS and have them fix it, so need to do it myself on the cheap!
 

Twenty Inch

New Member
Location
Behind a desk
When this happened to me, it turned out that my forks were slightly bent. Try and get them facing dead ahead, and then see that the drop-outs are in line with each other.
 

mr Mag00

rising member
Location
Deepest Dorset
Glad you are ok, jeez, if you did that damage to the front end i wouldnt be riding the bike at all until it was checked out completely. The forks may collapse the headset tube could be cracked, the energy from that crash had to go somewhere and to warp a disc brake !!!
trying not to be alarmist but seriously get it checked out.
 

TheDoctor

Resistance is futile!
Moderator
Location
Stevenage
You know how to check for a bent frame, yeah?
String from rear dropout on one side, up round the head tube, back to the other drop out and measure distance from string to seat tube - should be identical on either side? Yeah, course you do.
And obviously you've checked for crumples and flaking paint, often on the bottom of the down tube?

Dunno why I mentioned it really.:biggrin:
 

Danny

Legendary Member
Location
York
TheDoctor said:
You know how to check for a bent frame, yeah?
String from rear dropout on one side, up round the head tube, back to the other drop out and measure distance from string to seat tube - should be identical on either side? Yeah, course you do.
And obviously you've checked for crumples and flaking paint, often on the bottom of the down tube?

Dunno why I mentioned it really.:biggrin:
Will this really work? I presume Alcdrew would have spotted if his frame was seriously bent, so it seems to me that any bend is going to be pretty small(maybe mms). String is pretty floppy stuff so unless you have it perfectly evenly tensioned on both sides of the bike, there could be differences in length on either side would could be bigger than any bend in the frame.
 

TheDoctor

Resistance is futile!
Moderator
Location
Stevenage
Dannyg said:
Will this really work? I presume Alcdrew would have spotted if his frame was seriously bent, so it seems to me that any bend is going to be pretty small(maybe mms). String is pretty floppy stuff so unless you have it perfectly evenly tensioned on both sides of the bike, there could be differences in length on either side would could be bigger than any bend in the frame.
Yes it does work. Obviously the string needs to be tight, and given that it's running round a tube, the tension in each 'run' should be much the same. As long as the string is tight, it'll be straight. Then measure from the seat tube out to the string, and it should be as-near-as-dammit identical on each side. To clarify, I'm measuring seat-tube to string here, not the actual length of the string. It's tricky to explain without a diagram.
 

02GF74

Über Member
the fact that you got dics brake implies you have mountain bike.

and most likley to have suspension forks. these have an alloy crown with a steel tube pressed in - YOU MUST CHECK THIS IS NOT DAMAGED!

get LBS or someone who knows a bit more about bikes to check it out,

What is the point of having savied £ 30 when you are dead or in a wheelchair?
 

Danny

Legendary Member
Location
York
TheDoctor said:
...To clarify, I'm measuring seat-tube to string here, not the actual length of the string. It's tricky to explain without a diagram.
Ah...that makes more sense. I thought you were measuring whether the lengths of string on either side were the same ;)
 

fossyant

Ride It Like You Stole It!
Location
South Manchester
Down to the LBS to get it checked - you don't say what the bike is made of - I'd advise it even if steel, as you've probably got something out of alignment - especially if it's not just the bars twisted out of straight.
 

hubgearfreak

Über Member
string does give a straight line, of course.

builders use it between corners when laying bricks.

sheldon brown used it when checking coldset steel frames.

TheDoctor said:
To clarify, I'm measuring seat-tube to string here, not the actual length of the string. It's tricky to explain without a diagram.
http://www.sheldonbrown.com/frame-spacing.html

if it was good enough for him;)

you can use it on front forks aswell.

what are they made of? does a magnet stick to them?
if it does they're steel and a good framebuilder could get them perfect for you.

if they're not steel, they're scrap, i'm afraid
 
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