# Rigid Fork Measure



## Offtime3123 (Dec 28, 2006)

I'm rebuilding an old hardtail as a rigid SS for commuting and some single track riding. It had an old RockShox Judy TT, 80mm travel. I measured the axle to crown distance and am unsure about the size fork I want. I love the way the bike rode when it was all together and would like to keep its handling similar to the way it was. 
My problem is when I measured crown to axle I didn't know what part of the crown to measure it to. It's 16 inchs (approx. 400mm) from the bottom of the crown, 18 inchs (approx. 450mm) from the top of the crown. Which should I go with 16 or 18, or something in the middle? How much would the extra two inches effect the handling? Any input would be very helpful

thanks
m


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## blackhat (Apr 9, 2006)

clipped from dirt rag:

Take a pencil, a piece of string and a tape measure. Tie a length of string to the middle of the pencil. With the pencil placed in the fork dropouts, stretch the string taught to the surface of the fork where the headset crown race sites. Mark that point on the string with a pen and measure the distance from the center of the pencil to the mark in millimeters. This is your axle-to-crown length (L). If measuring a suspension fork, subtract roughly 10% of the overall travel form the overal lengtrh to account for suspension sag.

if it's an 80mm fork I think a surly 1x1 or a P2 would probably put you in the right ballpark.


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## Fat Bob (Mar 5, 2004)

I thought you measured to where your steer tube met the blades. I've always though it was where your crown race is set. I'm sure a real mechanic will step up and give you the solid answer any time though.


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## BikeMojo (Jan 6, 2005)

Fat Bob said:


> I thought you measured to where your steer tube met the blades. I've always though it was where your crown race is set. I'm sure a real mechanic will step up and give you the solid answer any time though.


Bob for the win.

Diagram courtesy of Vicious Cycles

The Axle to Crown height would be measurement B


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## CB2 (May 7, 2006)

You need to take in account your sag as well.
Tange makes a 400 mm axle to crown fork.
Surly's is 413 mm.
Salsa's is 425 mm.


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## single1x1 (Mar 23, 2005)

*425 or 430*



Offtime3123 said:


> I'm rebuilding an old hardtail as a rigid SS for commuting and some single track riding. It had an old RockShox Judy TT, 80mm travel. I measured the axle to crown distance and am unsure about the size fork I want. I love the way the bike rode when it was all together and would like to keep its handling similar to the way it was.
> My problem is when I measured crown to axle I didn't know what part of the crown to measure it to. It's 16 inchs (approx. 400mm) from the bottom of the crown, 18 inchs (approx. 450mm) from the top of the crown. Which should I go with 16 or 18, or something in the middle? How much would the extra two inches effect the handling? Any input would be very helpful
> 
> thanks
> m


 A Surly 413 or kona 410mm would probably quicken your HT angle a little bit, I like the quikened front end. But a 425 or 430mm would be closer to your 80mm fork when accounting for sag. Kona and surly both say they are suspension corrected for 80mm fork, but in reality they are both probably a little short, they will both fit a 3.0 gazzi tire though, the Kona is close though, a 2.5 nbx DH is big enough though and still heavy.
and measure to the crown race.


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## Offtime3123 (Dec 28, 2006)

How much difference in feel would I get between two rigids that are 10mm apart? 10mm doesn't seem that big a deal. But I'm starting to think otherwise.


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## Cloxxki (Jan 11, 2004)

Fork offset will change things more. Judy's run 38mm I think, rigids tend to run 43-45mm, which ks worth around the same as 20mm difference in axle-crown. More offset means quicker handling. IMO offset is a better way to reach quicker handling than a shorter/steeper front end though.
I've ridden Judy's and replaced them with 405-425mm forks. There's a difference, but I was fine with it. The 405mm made it a razor like trigger happy bike, which in some races gave me an edge, in others it proved a real handfull.


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## bob1 (Oct 27, 2006)

just done the same thing with my old frame and went for a set of pace rc31s in the 420mm size and they work really well. The Judy t2s at 80mm with 25mm to 30mm of sag worked out at 420mm from crown to drop outs...so not changed the overall feel of the bike and if its has I dont notice it...apart from the bumps!


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## Offtime3123 (Dec 28, 2006)

I've looked at the Pace forks. Carbon right? And in my mind, Carbon=$$$$$. I don't really want to spend alot because I don't know how much trail this bike will actually see. Mostly for commuting. Any suggestions? UniversalCycles.com is the only place I've really found a good selection of rigids. Oh... And Disc brakes are a must.


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