Advertise on Bikeforums.net



User Tag List

Results 1 to 16 of 16
  1. #1
    2k miles from the midwest Dylansbob's Avatar
    Join Date
    Feb 2005
    Location
    Washington
    My Bikes
    Sanner porteur ss, Soma Double Cross DC, Airborne Sortie, Bridgestone MB5
    Posts
    583
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(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?

  2. #2
    Elitist Troglodyte DMF's Avatar
    Join Date
    Jun 2006
    Location
    Dallas
    My Bikes
    03 Raleigh Professional (steel)
    Posts
    6,896
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Try asking this in the Framebuilders forum.

  3. #3
    me have long head tube TallRider's Avatar
    Join Date
    Oct 2005
    Location
    Chapel Hill, NC
    Posts
    4,098
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(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.

  4. #4
    Senior Member
    Join Date
    Oct 2005
    Posts
    5,432
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(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

  5. #5
    You Know!? For Kids! jsharr's Avatar
    Join Date
    Apr 2005
    Location
    Just NW of Richardson Bike Mart
    My Bikes
    '05 Trek 1200 / '90 Trek 8000 / '? Falcon Europa
    Posts
    6,084
    Mentioned
    12 Post(s)
    Tagged
    3 Thread(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.

  6. #6
    Senior Member
    Join Date
    Nov 2005
    Location
    NW Ohio
    My Bikes
    1984 Miyata 310, 1989 Club Fuji, 1986 Schwinn Sierra, 2011 Jamis Quest, 1980 Peugeot TH8 Tandem
    Posts
    1,197
    Mentioned
    3 Post(s)
    Tagged
    0 Thread(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

  7. #7
    You Know!? For Kids! jsharr's Avatar
    Join Date
    Apr 2005
    Location
    Just NW of Richardson Bike Mart
    My Bikes
    '05 Trek 1200 / '90 Trek 8000 / '? Falcon Europa
    Posts
    6,084
    Mentioned
    12 Post(s)
    Tagged
    3 Thread(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.

  8. #8
    Klaatu barada nikto cascade168's Avatar
    Join Date
    Sep 2004
    Location
    Southern NH
    Posts
    1,453
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(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.
    "Work is the curse of the drinking class."
    - Oscar Wilde

  9. #9
    You Know!? For Kids! jsharr's Avatar
    Join Date
    Apr 2005
    Location
    Just NW of Richardson Bike Mart
    My Bikes
    '05 Trek 1200 / '90 Trek 8000 / '? Falcon Europa
    Posts
    6,084
    Mentioned
    12 Post(s)
    Tagged
    3 Thread(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.

  10. #10
    Klaatu barada nikto cascade168's Avatar
    Join Date
    Sep 2004
    Location
    Southern NH
    Posts
    1,453
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(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.
    "Work is the curse of the drinking class."
    - Oscar Wilde

  11. #11
    me have long head tube TallRider's Avatar
    Join Date
    Oct 2005
    Location
    Chapel Hill, NC
    Posts
    4,098
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(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...

  12. #12
    Klaatu barada nikto cascade168's Avatar
    Join Date
    Sep 2004
    Location
    Southern NH
    Posts
    1,453
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(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.
    "Work is the curse of the drinking class."
    - Oscar Wilde

  13. #13
    Senior Member Road Fan's Avatar
    Join Date
    Apr 2005
    Location
    Ann Arbor, MI
    My Bikes
    Terraferma 650b, Mondonico SL and ELOS, Masi Gran Criterium, Trek 610, Breezer Liberty, Georgena Terry Classic
    Posts
    11,108
    Mentioned
    6 Post(s)
    Tagged
    0 Thread(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.

  14. #14
    Klaatu barada nikto cascade168's Avatar
    Join Date
    Sep 2004
    Location
    Southern NH
    Posts
    1,453
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(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.
    "Work is the curse of the drinking class."
    - Oscar Wilde

  15. #15
    Elitist Troglodyte DMF's Avatar
    Join Date
    Jun 2006
    Location
    Dallas
    My Bikes
    03 Raleigh Professional (steel)
    Posts
    6,896
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(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.

  16. #16
    Senior Member
    Join Date
    Oct 2005
    Posts
    5,432
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(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

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •