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The Street => The Bike Shop => Topic started by: Prodigal Son on July 06, 2016, 03:05:17 PM

Title: Measuring Fork Symmetry
Post by: Prodigal Son on July 06, 2016, 03:05:17 PM
My pitch are crooked or something. My wheel isn't centered and putting it in another set it is. How do I measure the varying componentary to figure out whether the legs or dropouts are affected?
Title: Re: Measuring Fork Symmetry
Post by: torontoflatlander on July 06, 2016, 05:05:51 PM
http://www.parktool.com/product/frame-and-fork-end-alignment-gauge-set-ffg-2?category=Frame%20&%20Fork

most bike shops should have a pair
Title: Re: Measuring Fork Symmetry
Post by: cmc4130 on July 07, 2016, 11:34:30 AM
Quote from: torontoflatlander on July 06, 2016, 05:05:51 PM
http://www.parktool.com/product/frame-and-fork-end-alignment-gauge-set-ffg-2?category=Frame%20&%20Fork

most bike shops should have a pair

doesn't that tool assume that the fork is made correctly, and it's just aligning it so that you tighten your stem at exactly 90 degrees to the wheel....?

i have definitely seen bmx forks where it looks like one fork leg is slightly in front of the other one, even when the front wheel axle is 90 degrees to the top tube and the front wheel is not bolted in crooked....
Title: Re: Measuring Fork Symmetry
Post by: torontoflatlander on July 07, 2016, 05:14:27 PM
Quote from: cmc4130 on July 07, 2016, 11:34:30 AM
Quote from: torontoflatlander on July 06, 2016, 05:05:51 PM
http://www.parktool.com/product/frame-and-fork-end-alignment-gauge-set-ffg-2?category=Frame%20&%20Fork

most bike shops should have a pair

doesn't that tool assume that the fork is made correctly, and it's just aligning it so that you tighten your stem at exactly 90 degrees to the wheel....?

i have definitely seen bmx forks where it looks like one fork leg is slightly in front of the other one, even when the front wheel axle is 90 degrees to the top tube and the front wheel is not bolted in crooked....

This is not the tool you're thinking of. (This might be - http://www.bike-discount.de/en/buy/tune-spurtreu-alignment-tool-for-handlebar-stem-412172)

 This is to match the sqareness and concentricity of the dropouts. The way they're made, you can tell pretty easily if your dropouts are square to eachother, both face forward at 90 degrees to where the hub interfaces with the dropouts, and if one dropout is sitting higher or lower than the other. On rare occasions (Usually Aluminum only), you'll be able to use these tools to straighten out minor bends. They're really wonderful things. I just haven't added them to my toolbox because, thru-axles and carbon are my world now.
Title: Re: Measuring Fork Symmetry
Post by: bsd510 on July 08, 2016, 04:25:08 PM
You can use a piece of string and hold it in the middle of the head tube and see if the other end of the string is equidistant to each dropout tip. Not the most precise but it works
Title: Re: Measuring Fork Symmetry
Post by: Prodigal Son on July 08, 2016, 11:03:03 PM
Quote from: bsd510 on July 08, 2016, 04:25:08 PM
You can use a piece of string and hold it in the middle of the head tube and see if the other end of the string is equidistant to each dropout tip. Not the most precise but it works

Speaking of precision, how do you determine your piece of string is at the radius?