[python] Sorry, one more revision: vp1_version2.gif (28kb)
- From: Michael Rienstra <ageless@xxxxxxxxxxxxx>
- To: python@xxxxxxxxxxxxx
- Date: Fri, 24 Sep 2004 01:42:55 -0700
Hello All,
Sorry to post almost the same thing twice in one night -- at least, despite the large size of the pictures, together they only total 60 kb, which isn't so bad.
Here's vp1_version2.gif (again, it's big -- 2000 px by 800 px, so save and view in something besides your mail program for better quality):
Here is the info:
vp1_version2.psd / vp1_version2.gif
Based on photoshop canvas size of 2000x800 px Scale 1 px = 1 mm
vp1 wheelbase: 1170 mm
32-507 tire: 576 mm dia
44-507 tire: 590 mm dia
hubs: 40 mm dia (arbitrary)
skewers: 5 mm dia
(center of rear tire located at 305,505)
(center of front tire located at 1475,505)
1.5" tubing height = 38.1 mm
0.5" tubing width = 12.7 mm
seat support fork width = 20 mm [not pictured in this version]
BB shell width: 35 mm
steering angle: 69 deg
BB - EOS: 680 mm
BB - FWaP: 395.5 mm
C - FWap: 309.5 mm
BB - C: 705 mm
Y: 170 mm
G - BB: 875 mm
rear frame member: 718 mm -9.6 deg
ground clearance: 148 mm (155 mm with 44-507 tires)
seat height: 300* mm (307* mm with 44-507 tires)
Gap between EoS - TEFT: 17 mm (11 mm with 44-507 tires)
Gap between C - TEFT: 16.5 mm (8.5 mm with 44-507 tires)
____
*Whoops! I just realized that I was using seat height = 300 mm to located the EoS point, but this isn't right, because the seat base isn't flat! So I guess my actual seat height will be slightly less than 300 mm, maybe 40 mm less or so? 260 mm perhaps?
To download the photoshop file, go to:
http://briefcase.yahoo.com/bc/mrienstra@xxxxxxxxxxxxx/lst?.dir=/public/ Vython
____
Just came up with a 'good' (but surely not very original) technique for figuring out the frame geometry.
Start with the FWA, then locate the EoS, based on your desired seat height. Then make a circle around FWA with the radius equal to FWA - BB, for example, 400 mm to 430 mm. Then make a circle around EoS with the radius equal to EoS - BB, based on your inseam and crank length. The intersection of these circles will give you the BB position. Then you can fiddle around with different angles of the front frame, to find something that passes close above the FWA, with proper ground clearance, and with enough room between TEFT and the ground clearance line for a decent value of Y (four bar linkage length) -- you may remember I wanted to go for the maximum I thought could be crammed under the seat, 250 mm, then it was 180 mm, now I am using 170 mm. Of course Y doesn't have to be parallel to the front frame, but it sure seems like it would make it easier to build. Sorry this is probably quite confusing with all of the abbreviations and whatnot, but it is 1:00 am and I'm tired and I'm going to be very very tired when I wake up at 4:20 am!
But I will be too busy tomorrow (friday) to finish the design, and I have to work saturday morning, then I will be building with my friend, so I must be ready!
Michael
PS: I think it's close enough for a prototype -- just gotta figure out the seat, but I guess we can just make that up after the rest of the frame is finished...
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- » [python] Sorry, one more revision: vp1_version2.gif (28kb)
