Technical & Reference Section > Tech and Restoration

Team fatgoose

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snoopy72:

--- Quote from: oldschoolace on April 04, 2015, 10:54 PM ---I'm no engineer but I would have thought the blue sections would need a 3rd arm to form a triangle to impart any sort of rigidity  ???

--- End quote ---
The small gusset should cover that ok

snoopy72:

--- Quote from: glenboy on March 20, 2015, 10:59 AM ---Saw this reminded me of yours



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The problem with this design is that your heels will smack the bottom stay and if you put your foot back in it's natural position it could be pretty painful on the up stroke .
Also it needed bracing the top and bottom stays together where the outside circumference of the rear wheel is.

rodriguez:
The weakest point won't necessarily be at the weld especially in an old frame, it could crack 2-3 inches up depending on where the greatest amount of stress from the torque of the pedal stroke is, then there'd be other factors such as corrosion internally, so I don't reckon that modification will necessarily stop it.

A brace at either side of the bottom bracket to the seat tube would be what I'd go for in addition to the gusset if you are going to go down that route, that would cover stress caused by front to back, up and down and side to side movement.

I'd be inclined to leave it alone, if it breaks get it fixed, definitely wouldn't be drilling holes in it.

snoopy72:
There's no drilling, it's all lightweight alloy clamps, sorry the sketch does look like i've drilled through the frame .
The 2 clamps are these using longer bolts for the rose joints. It's all removable and adjustable
This will be mirrored on the non drive side, this sketch is drive side only.
Would it make it stronger of worse ? you could argue that it could now be weak just the other sides of the clamps and fracture their. A very quick sitting on the bike version below.
It should cover front/back and up/down stress but it will still allow some side to side.
Might start looking like the Eiffel tower if i'm not careful :LolLolLolLol:
 Most flex will be generated though the Dura ace cranks






Think Griff's pic sums it all up really :LolLolLolLol:

rodriguez:
If I was going to have a brace between the seat tube and down tube I'd brace either side of the seat tube to the BB and possibly at the back.

Sketch on the back of an envelope.

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