Head angle

[RodTi]

Hello all,

 

Would appreciate some thoughts on the following:

 

I'm sitting with a frame that has an old-skool, head-angle geometry of 71.5 degrees - this with a 80mm on the front.

 

I've been told that putting a longer fork on the front, will make things too slack, and throw out the ride...

But I'm not so sure?

 

What effective difference in angle would an increase of 20mm in front have?

Most "steep/tight" frames are sitting between 70 and 71 degrees - with a "slack" AM/DH frame sitting at 65 - 66 degrees... Surely with mine starting at 71.5, an extra 20mm cannot bring the angle down too drastically below the 70 degree range?

[Wernervdmerwe]

Nope, you lose about 1deg per 20mm.

Remember that running a longer fork than the manufacturer max will place higher stress on your head tube and can result in failure.

[Capricorn]

what WvdM said. Check what fork travel length your frame is rated for. but u said old school, so might be hard to find that info

[Wernervdmerwe]

Oh yeah - also remember that it influences your BB height and seatpost angle as well, so your climbing and cornering will be affected as well....

 

Why would you like more travel? Do you find you bottom out too much, or do you want to change HA due to the benefits in going down?

Maybe knowing what you are trying to improve will lead to possibly more helpful advice / changes?

[RodTi]

Thanks guys! Ja, it's not something I'd do, but I was wanting to confirm my thoughts pertaining to the Head Angle issue...

 

The frame, albeit titanium - and so relatively durable - is more than a decade old, and originally had a 50mm on... Methinks that to say a 100mm might be pushing it, would be a bit of an understatement!