# Will a change in fork offset affect head angle?



## mikael_on_wheels (Jun 10, 2019)

I need to replace a stock rigid fork (with a new rigid fork). Head tube angle of the frame is 71 degrees.

The stock fork has a 468 mm a-c measurement and a 42 mm offset.

The fork I'm considering buying a replacement fork that has a 470 mm a-c measurement and a 50 mm offset.

Would a fork with more offset change the head angle and would I need a longer a-c measurement to compensate for that?

Is the new fork likely to change the handling of the bike a lot? According to a calculator the trail will go down from 81 mm to 73 mm.


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## *OneSpeed* (Oct 18, 2013)

mikael_on_wheels said:


> I need to replace a stock rigid fork (with a new rigid fork). Head tube angle of the frame is 71 degrees.
> 
> The stock fork has a 468 mm a-c measurement and a 42 mm offset.
> 
> ...


That fork will work just fine. The A-C measurement is more important than the offset in this scenario. You will notice the front end steering will be a little quicker with a 50 offset. But you will adapt quickly to the minor difference in front end steering feel. Nothin to worry about.


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## mikael_on_wheels (Jun 10, 2019)

*OneSpeed* said:


> That fork will work just fine. The A-C measurement is more important than the offset in this scenario. You will notice the front end steering will be a little quicker with a 50 offset. But you will adapt quickly to the minor difference in front end steering feel. Nothin to worry about.


Thanks!


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## mikesee (Aug 25, 2003)

*OneSpeed* said:


> That fork will work just fine. The A-C measurement is more important than the offset in this scenario. You will notice the front end steering will be a little quicker with a 50 offset. But you will adapt quickly to the minor difference in front end steering feel. Nothin to worry about.



Yep.


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## Joe Handlebar (Apr 12, 2016)

A little late to the post here but....the "thing" that changes with fork offset (also known as fork rake) is the "trail" measurement. The 2mm in the AtC measurement is negligible for HTA, but trail does affect the way a bike handles. The more trail, the more "stable" the bike becomes on it's own. In fact, if you build in enough trail, a bike will literally self-correct itself without a rider until it just falls over (lol...ask me how I know)...completely impracticable...but relevant for this example. Less trail results in what many riders call "wheel flop"on modern bikes, especially while climbing and pedaling on the flats. In practice, it really is more of a "road bike" thing...mostly...I think, I dunno, but I prefer to have a little more trail than less which is why I run a 42mm offset on my 29er which has a 66° HTA, but that's just me.


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