Dylansbob 

I'm want to play around with some shorter length rigid forks to quicken up the handling of of my around-town beater. It's made for a 63mm fork with a 71.5 degree now and I'm hoping to get it steepened up to closer mimic a road bike feel. Any advice?

DMF 

Try asking this in the Framebuilders forum.

TallRider

Easiest way I've found is to take a photo of the bike from the side, from a distance away. Get it into photoshop or whatever photo-editing program, and see how many degrees of rotating the picture gets you to horizontal or vertical. I've used this for seat tube angles, it'll be harder with head-tube b/c it's not as long as seat tube, but should still be an easy method.

San Rensho 

Great idea, I may try a variation. Take a photograph of the head tube/top tube, enlarge the photograph then draw a line through the center of both and measure the angle where they intersect.

What I've done, that doesn't work very well, is use a spirit level and get the top tube level. Then put a protractor against the head tube and use a plumb bob to read the angle. Its pretty crude, I could barely get it within a degree.

jsharr

they sell adjustable squares at hardware stores

Pompiere

Sears sells an angle finder, basically a weighted protractor that you set against whatever you want to find the angle of.
https://www.sears.com/sr/javasr/produ...seBVCookie=Yes

jsharr

They also sell a sliding bevel square for $5. Use this with your protractor and you save some serious cash and have a useful woodworking tool to add to your collection

https://www.sears.com/sr/javasr/produ...id=00939582000

cascade168

Better yet, if you're going to Sears ....

Get this one for $4.99:

https://www.sears.com/sr/javasr/produ...seBVCookie=Yes

It works just fine for determining tube angles.

jsharr

the adjustable bevel square does not depend on having the bike level, where the other methods do. Just set it to match the angle between top tube and head tube and then lay it on top of a protractor and you have the angle. I do not own the bubble type angles, I do own the bevel square, but I have never used it for this purpose. heck you could take two pieces of wood that had a straight edge and run a single screw through them and make and angle finder for free with stuff you may have laying around.

cascade168

With an angle finder (like the ones that Pompiere and I linked to) the bike does not need to be level. Those finders use a gravity driven indicator (just like a plumb bob). You just take two readings (one for the top tube and one for the head tube) and figure the difference. The bike can be sitting at any angle, as long as the plane of the frame is perpendicular to the ground, and this method will still work.

TallRider

aso, it sounds as if this method depends on the top tube being horizontal, which is the case with some road bikes, and most older road bikes (and a few older mountain bikes). but not consistent enough to be one's main method of finding HT or ST angles.
I'd be more confident that my floor is level than I would that the top tube is horizontal when the wheels are level...

cascade168

You bring out an important point and yet another reason to own a angle finder.

The beauty of the angle finder is that it can tell you if your floor is level. You just sit it on the floor and if the pointer is at 90deg (i.e. straight down), then your floor is level. Then you check the top tube and see if it's at 90deg. If so, then it's truly parallel to the floor. If not, then you just do your calculating accordingly. This is the easy way to find the rise angle on a top tube that's not parallel to the floor.

Road Fan

If you're going to get an angle finder, the Ace Hardware one is easier to read than the Craftsman.

cascade168

I'll be honest, that one that I linked to is not as nice as the one I got at Sears. I think I paid more like $10 for mine. I'd guess there are plenty of places you can get them in varying quality and functionality.

DMF 

I think y'all are mis-reading the question. Sounds to me that he wants to *change* the HT angle, not just measure it.

San Rensho 

To get the head tube angle steeper, either lower the front with a smaller diameter wheel, or raise the rear, with a larger wheel.