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[Closed] Head angle/bigger forks.

 Elmo
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[#3396642]

What difference does It make and can you work it out easily?

I had a commencal frame with dead 100mm forks.
I put some spare 140mm forks on it, it was-in hindsight obviously-a horrible thing to try and ride up any incline!
I'm now looking at other frames to take the forks.
There's a couple of secondhand frames ive seen that were originally spec'd with 130mm forks. Im trying to figure would the take a 140 fork without leaving me in the same predicament?


 
Posted : 27/11/2011 3:03 pm
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IIRC every inch of unsagged fork length is 1 degree more rake - roughly

10 mm will make little difference and most forks can have internal spacers added to reduce length


 
Posted : 27/11/2011 3:09 pm
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17mm = 1 degree - after sag.


 
Posted : 27/11/2011 3:21 pm
 Elmo
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So maybe .5 of a degree.
That should be ok, when I put it on the commencal I knew it would be odd. But I never thought it would be that bad!

Looking at a main rocky ridge(maybe)and a felt Trail shot.
Both of these should be happy with 140mm forks(I think!)


 
Posted : 27/11/2011 3:36 pm
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The increased BB height makes a fair difference to centre of gravity too, especially riding slowly up hill.

Depends on the frame, my old Giant trance should have had 100mm forks on it but was great with 130mm and many say 140mm is the best.

A frame with a too low BB and steep angles will be improved by over forking, I reckon.


 
Posted : 27/11/2011 5:30 pm
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yep, went from 90mm to 130mm on my ancient mount vision. total improvement.


 
Posted : 27/11/2011 8:00 pm
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Depends on wheel base etc but ~20mm on fork length gives a degree slacker.

Don't forget some forks have a shorter axle to crown length than others, so you could get more travel for the same length.

IIRC Magura Menja 130's were pretty short for 130 forks, Fox are quite short. Marzocchi's used to be quite long but have got shorter.

The Suntour Durolux fork I've just bought is 550mm axle to crown whereas a Rockxhox Domain 180 is 565mm.


 
Posted : 27/11/2011 11:10 pm
 Elmo
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I always knew it would make a difference. But I was figuring it would be one of those differences that only really made a difference if you were "at a certain level" of riding.
But I'm a mid level rider at best and I could feel the bike was harder going somehow. And on a path I knew, on bits I knew I could ride up(albeit slowly!)I couldn't keep the front down, or even in traction.

This is when I realised how little I know about bike setup :oops:..........


 
Posted : 27/11/2011 11:24 pm