Measuring Frame Angles

[Tony DeFilippo]

I've been enjoying my ~1970's, (possibly) Bob Jackson mystery frame w/ 700x32 Compass EL tires so much lately I've been getting curious about the frame geometry. It appears to have slightly steeper angles and definitely has a compact rear triangle... anyway I took a nice clean profile shot on my ride this morning and googled for measuring angles on a computer screen this evening.  Low and behold there is a Google Chrome browser Extension called "MB-Ruler for Chrome".  It's not perfect and I don't have any illusions about the absolute accuracy of this method but it is fun to play with.  Maybe there are some other tools out there you've used and want to share?

I had to flip the photo horizontally for the HB-Ruler tool to be able to read easier, to bad you can't flip the tool.  These shot's are quick screen grabs of the photo which I uploaded into flickr so I could use the chrome extension on them from the browser.  Not terribly necessary on your more recent Riv's w/ known geo but might be a fun distraction messing around w/ an older frame.

HT Angle = ~74deg (this one was harder to measure w/o having a clear spot to place the compass base)

ST Angle = ~73.4deg (i'm more confident about this one)

Two more w/o any angles shown... gorgeous crisp morning at my Mom's place at Lake Waccamaw NC. I'm here through Thursday and plan to ride every day... can't do better from a light perspective to what I saw this morning though!  I'm going to put out some blog/flickr posts later this week with more of my favorites.

[WETH]

Tony,
You have the bike built up nicely. The area around your mom's looks lovely. Any mother and son rides planned?
Thanks for sharing the tool. I can see hours of fun measuring and comparing some of my mystery frames/bikes.
Thanks,
Erl

[Tony DeFilippo]

Thanks Erl! Not this trip, I'm down here to help out while she recovers from hip surgery so unfortunately she'll be out of action for a while. She's doing really well though and I'm able to get out for some decent length rides.

Tony

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[iamkeith]

I use a free ap on an android phone, called Smart Protractor Light.   It's pretty sensitive so, obviously, you need to be on a level surface and make sure the bike is perfectly plumb.   Works best if you have a phone that doesn't have buttons protruding from the side, or if you fit around them with sort of spacers, like popsicle sticks.  That Chrome ruler is neat though - thanks for posting.

https://play.google.com/store/apps/details?id=kr.sira.protractor.

[Chris Lampe 2]

You can use BikeCad to design bikes and it's pretty easy to get really close to the geometry of a real bike (angles unknown) just by eyeballing it.  I did this with Riv's photos of the 52cm Clem and I wasn't off by more than .5 degrees on any angle.  Plus, it's a blast to design your own bikes and the free version of BikeCad is plenty comprehensive for just playing around.