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Mantis, Paramount, Campy
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A Bike With A 69 HA Can Climb?

That is super-slack to start with.
I'd say that if you're used to climbing on a 69deg head angle that the change to 67 won't make too much of a difference.
 

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Just another FOC'er
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Shayne said:
That is super-slack to start with.
I'd say that if you're used to climbing on a 69deg head angle that the change to 67 won't make too much of a difference.
69 super slack? My XC bike is at 68 degrees. ;)

What shiggy says is very true though. The most important thing that helps me with climbing is being able to achieve the right front/rear weight balance and to not feel like I'm falling over backwards due to geometry. All of my bikes are slack and I use fork height adjustment to steepen up the HA for climbs. More importantly it helps get my weight forward more due to geo change so I don't have to sit on the tip of the seat.

Even with a similar geometry 67 will push a bit more on climbs that 69. With 67 you've got to get even more weight on the front which can cause the back to spin.

Going down 67 feels entirely different than 69. 69 is extremely twitchy for me. It always interested me that such a small HA sweet spot exists.
 

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.Danno. said:
...Going down 67 feels entirely different than 69. 69 is extremely twitchy for me. It always interested me that such a small HA sweet spot exists.
Partly because there is little or no choice in fork offset. The combo of HTA and fork offset (and tire diameter) determines trail. The amount of trail is what makes a bike stable, twitchy or floppy.
 

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Shayne said:
That is super-slack to start with.
I'd say that if you're used to climbing on a 69deg head angle that the change to 67 won't make too much of a difference.
No, that's pretty much standard these days for all but pure XC race bikes. Your average trail bike with 100-120mm fork comes in around 69.5-69 degrees these days, a XC race bike will be in the 70-71 degree range (with Hardtails usually being a bit steeper than full squish)
 

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Discussion Starter · #9 ·
.Danno. said:
69 super slack? My XC bike is at 68 degrees. ;)

What shiggy says is very true though. The most important thing that helps me with climbing is being able to achieve the right front/rear weight balance and to not feel like I'm falling over backwards due to geometry. All of my bikes are slack and I use fork height adjustment to steepen up the HA for climbs. More importantly it helps get my weight forward more due to geo change so I don't have to sit on the tip of the seat.

Even with a similar geometry 67 will push a bit more on climbs that 69. With 67 you've got to get even more weight on the front which can cause the back to spin.

Going down 67 feels entirely different than 69. 69 is extremely twitchy for me. It always interested me that such a small HA sweet spot exists.
Sounds like you sacrifice a little either way. I am thinking the 67 with an adjustable fork might be the way to go. After all, what goes up must come down.
 

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shiggy said:
Partly because there is little or no choice in fork offset. The combo of HTA and fork offset (and tire diameter) determines trail. The amount of trail is what makes a bike stable, twitchy or floppy.
I've always been curious about the reasoning behind the large offset on my DH forks. I'm guessing the ideas is that reducing trail with a larger offset tends to speed up steering slowed by the slack angles.

I've got an old Mag21 on a hardtail that has zero offset and it's really stable to ride no handed because of the long trail.
 

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.Danno. said:
I've always been curious about the reasoning behind the large offset on my DH forks. I'm guessing the ideas is that reducing trail with a larger offset tends to speed up steering slowed by the slack angles.

I've got an old Mag21 on a hardtail that has zero offset and it's really stable to ride no handed because of the long trail.
Slacker HTAs need more fork offset to keep the trail reasonable.

The Mag21 has ~40mm of offset built into the crown.
 

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shiggy said:
The Mag21 has ~40mm of offset built into the crown.
Interesting, my description wasn't entirely accurate though. The fork is actually a Specialized Future Shock, which I thought was identical to a Mag21. I use 'Mag21' so people know what I'm talking about. I just checked the crown offset and it looks like ~15mm.
 
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