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Discussion Starter · #4 ·
not really hard...

you just have to make sure that you have a level floor and that your bike is standing up straight. The headbadge doesn't get in the way and if it does, you can always get some blocks so you can measure against the headtube instead of the badge...
The angle finder was less than $10 at Home Depot... The head tube is better as a frame of reference since some fork legs are offset at the crown..
 

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Need education

flipnidaho said:
you just have to make sure that you have a level floor and that your bike is standing up straight. The headbadge doesn't get in the way and if it does, you can always get some blocks so you can measure against the headtube instead of the badge...
The angle finder was less than $10 at Home Depot... The head tube is better as a frame of reference since some fork legs are offset at the crown..
Hey Flipn
Thanks for sharing. Now I need some education on the effect of HA on different riding perspectives. Like I know that when I added travel to my HT (changed HA), the handling slowed a bit. But I am sure there are many more aspects to why people preffer to build bikes to a specific range of HA.
Cheers
GB
 

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Discussion Starter · #6 ·
GreenBonty said:
Hey Flipn
Thanks for sharing. Now I need some education on the effect of HA on different riding perspectives. Like I know that when I added travel to my HT (changed HA), the handling slowed a bit. But I am sure there are many more aspects to why people preffer to build bikes to a specific range of HA.
Cheers
GB
The general rule of thumb is:
Taller fork = shallower HA = more stable on descents but the front can feel "wallowy" on the climbs and if the fork is too tall it can wheelie on really steep climbs (which is why a lot of 5" + forks have some sort of travel adjustment)
Shorter fork = steeper HA = super quick on singletrack (you just think turn and the bike is already turning) but a handful on steep descents.
When I used to live out East, I really loved 75mm - 80mm forks for slicing and dicing. Out West, where the trails are wide open and super fast, I prefer a taller fork...
 

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It's also best to take two measurements. Once you take the first measurement, turn the bike around 180 degrees on the floor and then take another measurement and then average your two results. This will help to account for the fact that not all floors are perfectly level.
 

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flipnidaho said:
you just have to make sure that you have a level floor and that your bike is standing up straight. The headbadge doesn't get in the way and if it does, you can always get some blocks so you can measure against the headtube instead of the badge...
The angle finder was less than $10 at Home Depot... The head tube is better as a frame of reference since some fork legs are offset at the crown..
In theory the head tube and fork are parallel to each other. The angle should measure the same. I figure it would be better to measure at the fork since that is what determines how the bike handles because the tire is attached to it.

Measuring the angle twice with the bike facing 180 is good to know.
 

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Nagaredama said:
I figure it would be better to measure at the fork since that is what determines how the bike handles because the tire is attached to it.
wrong. angle of the steering axis is part of what determines trail, which is one aspect of bike handling. On most bikes the steering axis is parallel to the head tube (some 1.5 head tubes with reducers can be canted to the steerer is not parallel to the HT, but you know if you have one of those).

Most fork legs are more or less parallel to the steerer, but most also have some shaping on the legs, so it can be hit or miss as to the accuracy of the reading. Then again, measuring against the head badge almost certainly is compromising accuracy. I'd think a better way would be to put a straightedge between the headset cups and measure the angle of that.

Then again, it's pretty easy to calculate H/A based on manufacturer's published data and A/C lengths, assuming you have accurate info on both.
 

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I seem to recall that fork legs are NOT necessarily parallel to the steer tube; Fox in particular angles the stanchions back a little bit. The stanchions themselves should be totally smooth, and therefore a perfect surface to test this :)
 

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Discussion Starter · #11 ·
Joules said:
I'd think a better way would be to put a straightedge between the headset cups and measure the angle of that.
The headset cups on my 575 (Cane Creek S2) are a bit different. The lower cup is flush with the headtube while the upper cup sticks out quite a bit. Also the headtube on the 575 is flared at the top. The headbadge was good enough for government work... :D
 

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flipnidaho said:
The headset cups on my 575 (Cane Creek S2) are a bit different. The lower cup is flush with the headtube while the upper cup sticks out quite a bit. Also the headtube on the 575 is flared at the top. The headbadge was good enough for government work... :D
my fault, yeah the S2 uses a overlapping upper bearing cap to keep out water without really being "sealed" (whatever that means). I'm not sure what you mean about it being flared at the top - it just looks like it's externally butted to me (I know may ARC is, but it's butted at both ends), all the more reason a reading off the tube probably isn't that accurate - the inside of the head tube is parallel to the steerer (which is what matters), but the outside is not. If you have the stock thomson elite (not X4) stem you could put the clinometer on the back of the steerer tube above the head tube,

I know it's "close enough for government work" but between the accuracy of tools like that and the accuracy of the procedure, I'd be surprised if you are within 2-3° of the actual hta with your measurement. To me a measurement that inaccurate isn't worth taking.
 
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