65mm travel anD rigid offset

tomjasz

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Out riding, MN USA
The OEM fork for the frame i bought had 65mm of travel. When converting to a rigid fork, how does that translate to proper, or closest offset?
 
If you mean fork length to give the same headtube/steerer angle so the handling is the same, you'd want to measure the suspension fork length while it's compressed with your weight on the bike saddle (takes two people or setting up a jig with a marker on the crown and a board on the wall, and a bit of math).

THen get a fork with the same length from crown race to dropouts, and the bike will have the same angles so would "ride" the same.

Then measure the dropouts' offset from the steering tube and get a fork with the same offset, and it should handle the same there, too, giving the same trail.


This page may explain why these things change handling better than I can:
https://www.sheldonbrown.com/rinard/forklengths.htm
 
Thanks, not possible since it's a bare frame and I don't have the original fork.

Searching 2009 data,
Travel 63mm
SAG in % 15% - 20%
SAG in mm 9mm - 13mm
 
Original fork,

Spinner Enroute AC 26" Hybrid Bike Suspension Fork Coil 63mm Black *USED*
If you are looking for a fork with amazing results that doesn't hurt the wallet the Spinner Enroute AC fork is for you. Made with a steel steerer tube and 63mm of travel, this is a great choice for hybrid bike riders.

Preload adjustment
Bike Type: Hybrid
Wheel Size: 26"
Steerer Diameter: 1-1/8"
Steerer Length: 265mm
Brake Compatibility: Post or Disc
Travel: 63mm
Adjustments: Preload
Stanchion diameter: 25.4mm
Dropouts: 9mm
Inner Hub Spacing: 100mm
Color: Black
Weight: 2160g
 
There's no single answer for that. It's "whatever offset gives you the desired amount of trail". Trail is a function of head angle, wheel diameter, and fork offset.

The amount of trail you're looking for varies by riding style, typical speed, and amount of load carried on the front wheel. For a very fast bike, you want more trail. For a bike that carries lots of weight on the front, you want less trail. But you can't go much wrong shooting for about 2 inches of trail.

What kind of bike are you retrofitting with a new fork?

With MTB suspension forks, you don't really get to choose from among different fork offset values. They're all going to be right around 44mm. It isn't always right for the job, but it's what you get. If you can find a rigid fork with a little more offset, you might like the handling better.

The shorter the fork is from axle to crown, the less steering trail you'll have with the same fork offset.
 
good info in rake/trail/head tube angle interplay

scroll down to the "rake and trail 101"

http://www.chopperhandbook.com/rake.htm
 
Chalo said:
There's no single answer for that. It's "whatever offset gives you the desired amount of trail". Trail is a function of head angle, wheel diameter, and fork offset.

The amount of trail you're looking for varies by riding style, typical speed, and amount of load carried on the front wheel. For a very fast bike, you want more trail. For a bike that carries lots of weight on the front, you want less trail. But you can't go much wrong shooting for about 2 inches of trail.

What kind of bike are you retrofitting with a new fork?

With MTB suspension forks, you don't really get to choose from among different fork offset values. They're all going to be right around 44mm. It isn't always right for the job, but it's what you get. If you can find a rigid fork with a little more offset, you might like the handling better.

The shorter the fork is from axle to crown, the less steering trail you'll have with the same fork offset.

https://www.google.com/search?q=marin+stinson+2009+ez+step&ie=UTF-8&oe=UTF-8&hl=en-us&client=safari#imgrc=m1ETn3ZHsZdOHM:

I want to get as close to the upright position of my Trek Pure, Townie, or KHSto use on front.

Thanks
 
Sorry the changed method of posting pictures is almost as difficult as a PM! Confusing.
 
Lenk42602 said:
good info in rake/trail/head tube angle interplay

scroll down to the "rake and trail 101"

http://www.chopperhandbook.com/rake.htm

Thank you.
 
tomjasz said:
Lenk42602 said:
good info in rake/trail/head tube angle interplay

scroll down to the "rake and trail 101"

http://www.chopperhandbook.com/rake.htm

Thank you.

Careful! Motorcycle guys say "rake" when they mean head angle, and bicycle guys say "rake" when they mean fork offset. You have to translate.

For what it's worth, I think the best thing for you would be a super long fork, like a 29+ fork, but with extra generous offset, like 60mm. Tough luck finding one of those.

Short of that, try a fork without any suspension correction (not more than 400mm axle to crown), with more than 45mm offset, if you can find one. A framebuilder may be able to add offset to the steel fork of your choosing.
 
More data, Spinner EnRoute AC, 63mm with Preload Adjustment, crown to axle 420mm, pitch 107. Some specs call it a 40mm travel, others, same year a 63mm travel. What should the axle to crown length be corrected? All i find for corrected are for 100mm travel correction.
 

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