Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 04-29-07, 12:59 AM   #1
Dylansbob
2k miles from the midwest
Thread Starter
 
Dylansbob's Avatar
 
Join Date: Feb 2005
Location: Washington
Bikes: Novara Team mtb, Novara XR, Bridgestone MB5....all collecting dust
Posts: 604
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Is there an easy way to figure HT angle?

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?
Dylansbob is offline   Reply With Quote
Old 04-29-07, 10:02 AM   #2
DMF 
Elitist Troglodyte
 
DMF's Avatar
 
Join Date: Jun 2006
Location: Dallas
Bikes: 03 Raleigh Professional (steel)
Posts: 6,924
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Try asking this in the Framebuilders forum.
DMF is offline   Reply With Quote
Old 04-29-07, 10:23 AM   #3
TallRider
me have long head tube
 
TallRider's Avatar
 
Join Date: Oct 2005
Location: Chapel Hill, NC
Bikes:
Posts: 4,106
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
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.
TallRider is offline   Reply With Quote
Old 04-29-07, 11:06 AM   #4
San Rensho 
Senior Member
 
Join Date: Oct 2005
Bikes:
Posts: 5,540
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Quote:
Originally Posted by timcupery
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.

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.
__________________
Il faut de l'audace, encore de l'audace, toujours de l'audace

1980 3Rensho-- 1975 Raleigh Sprite 3spd
1990s Raleigh M20 MTB--2007 Windsor Hour (track)
1988 Ducati 750 F1
San Rensho is offline   Reply With Quote
Old 04-29-07, 01:05 PM   #5
jsharr
You Know!? For Kids!
 
jsharr's Avatar
 
Join Date: Apr 2005
Location: Just NW of Richardson Bike Mart
Bikes: '05 Trek 1200 / '90 Trek 8000 / '? Falcon Europa
Posts: 6,157
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
they sell adjustable squares at hardware stores

__________________
Are you a registered member? Why not? Click here to register. It's free and only takes 27 seconds! Help out the forums, abide by our community guidelines.
Quote:
Originally Posted by colorider View Post
Phobias are for irrational fears. Fear of junk ripping badgers is perfectly rational. Those things are nasty.
jsharr is offline   Reply With Quote
Old 04-29-07, 07:44 PM   #6
Pompiere
Senior Member
 
Join Date: Nov 2005
Location: NW Ohio
Bikes: 1984 Miyata 310, 1989 Club Fuji, 1986 Schwinn Sierra, 2011 Jamis Quest, 1980 Peugeot TH8 Tandem, 1992 Performance Parabola, 1986 Ross Mt. Hood
Posts: 1,708
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Sears sells an angle finder, basically a weighted protractor that you set against whatever you want to find the angle of.
http://www.sears.com/sr/javasr/produ...seBVCookie=Yes
Pompiere is offline   Reply With Quote
Old 04-29-07, 09:00 PM   #7
jsharr
You Know!? For Kids!
 
jsharr's Avatar
 
Join Date: Apr 2005
Location: Just NW of Richardson Bike Mart
Bikes: '05 Trek 1200 / '90 Trek 8000 / '? Falcon Europa
Posts: 6,157
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
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

http://www.sears.com/sr/javasr/produ...id=00939582000
__________________
Are you a registered member? Why not? Click here to register. It's free and only takes 27 seconds! Help out the forums, abide by our community guidelines.
Quote:
Originally Posted by colorider View Post
Phobias are for irrational fears. Fear of junk ripping badgers is perfectly rational. Those things are nasty.
jsharr is offline   Reply With Quote
Old 04-29-07, 11:00 PM   #8
cascade168
Klaatu barada nikto
 
cascade168's Avatar
 
Join Date: Sep 2004
Location: Southern NH
Bikes:
Posts: 1,453
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Pompiere
Sears sells an angle finder, basically a weighted protractor that you set against whatever you want to find the angle of.
http://www.sears.com/sr/javasr/produ...seBVCookie=Yes

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

Get this one for $4.99:

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

It works just fine for determining tube angles.
cascade168 is offline   Reply With Quote
Old 04-29-07, 11:09 PM   #9
jsharr
You Know!? For Kids!
 
jsharr's Avatar
 
Join Date: Apr 2005
Location: Just NW of Richardson Bike Mart
Bikes: '05 Trek 1200 / '90 Trek 8000 / '? Falcon Europa
Posts: 6,157
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
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.
__________________
Are you a registered member? Why not? Click here to register. It's free and only takes 27 seconds! Help out the forums, abide by our community guidelines.
Quote:
Originally Posted by colorider View Post
Phobias are for irrational fears. Fear of junk ripping badgers is perfectly rational. Those things are nasty.
jsharr is offline   Reply With Quote
Old 04-30-07, 12:02 AM   #10
cascade168
Klaatu barada nikto
 
cascade168's Avatar
 
Join Date: Sep 2004
Location: Southern NH
Bikes:
Posts: 1,453
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by jsharr
the adjustable bevel square does not depend on having the bike level, where the other methods do.
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.
cascade168 is offline   Reply With Quote
Old 04-30-07, 06:48 AM   #11
TallRider
me have long head tube
 
TallRider's Avatar
 
Join Date: Oct 2005
Location: Chapel Hill, NC
Bikes:
Posts: 4,106
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by 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.
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...
TallRider is offline   Reply With Quote
Old 04-30-07, 10:26 AM   #12
cascade168
Klaatu barada nikto
 
cascade168's Avatar
 
Join Date: Sep 2004
Location: Southern NH
Bikes:
Posts: 1,453
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by timcupery
I'd be more confident that my floor is level than I would that the top tube is horizontal when the wheels are level...
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.
cascade168 is offline   Reply With Quote
Old 04-30-07, 02:08 PM   #13
Road Fan
Senior Member
 
Road Fan's Avatar
 
Join Date: Apr 2005
Location: Ann Arbor, MI
Bikes:
Posts: 12,268
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 16 Post(s)
Quote:
Originally Posted by cascade168
Better yet, if you're going to Sears ....

Get this one for $4.99:

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

It works just fine for determining tube angles.
If you're going to get an angle finder, the Ace Hardware one is easier to read than the Craftsman.
Road Fan is offline   Reply With Quote
Old 04-30-07, 02:41 PM   #14
cascade168
Klaatu barada nikto
 
cascade168's Avatar
 
Join Date: Sep 2004
Location: Southern NH
Bikes:
Posts: 1,453
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Road Fan
If you're going to get an angle finder, the Ace Hardware one is easier to read than the Craftsman.
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.
cascade168 is offline   Reply With Quote
Old 05-01-07, 10:41 AM   #15
DMF 
Elitist Troglodyte
 
DMF's Avatar
 
Join Date: Jun 2006
Location: Dallas
Bikes: 03 Raleigh Professional (steel)
Posts: 6,924
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I think y'all are mis-reading the question. Sounds to me that he wants to *change* the HT angle, not just measure it.
DMF is offline   Reply With Quote
Old 05-01-07, 11:16 AM   #16
San Rensho 
Senior Member
 
Join Date: Oct 2005
Bikes:
Posts: 5,540
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Quote:
Originally Posted by 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?
To get the head tube angle steeper, either lower the front with a smaller diameter wheel, or raise the rear, with a larger wheel.
__________________
Il faut de l'audace, encore de l'audace, toujours de l'audace

1980 3Rensho-- 1975 Raleigh Sprite 3spd
1990s Raleigh M20 MTB--2007 Windsor Hour (track)
1988 Ducati 750 F1
San Rensho is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 09:43 PM.