Bike Porn V2.0
10-30-15, 11:07 AM
#4301
Team Beer
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Yup, the seatpost is cut. But look at how high the seat tube and binder are.
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I'm not one for fawning over bicycles, but I do believe that our bikes communicate with us, and what this bike is saying is, "You're an idiot." BikeSnobNYC
I'm not one for fawning over bicycles, but I do believe that our bikes communicate with us, and what this bike is saying is, "You're an idiot." BikeSnobNYC
10-30-15, 11:20 AM
#4302
canis lupus familiaris
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Once the seat post penetrates the seat tube past the top tube and the seat stays, the loads are transferred to the frame.
10-30-15, 11:26 AM
#4304
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I think it also depends on the butting profile of the seattube used. If the butt ran past the stays I'm sure it's strong enough.
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I'm not one for fawning over bicycles, but I do believe that our bikes communicate with us, and what this bike is saying is, "You're an idiot." BikeSnobNYC
I'm not one for fawning over bicycles, but I do believe that our bikes communicate with us, and what this bike is saying is, "You're an idiot." BikeSnobNYC
10-30-15, 12:08 PM
#4305
Senior Member
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You're probably right.
I would think notching a section of the seat post and leaving it long enough to extend past the seat stays would be a better solution than a tall mast and short post.
10-30-15, 12:16 PM
#4306
canis lupus familiaris
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Yes, that would help and it will probably work just fine, plus you can't beat the cool factor and the super clean look. It is just that I am not a fan of cantilevering loads like that.
10-30-15, 12:25 PM
#4307
Veteran Racer
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Just out of curiosity, do you have a structural engineering background ? Your comments seem to indicate something of the sort to me.
10-30-15, 12:46 PM
#4309
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I was reading about this earlier this morning cause I was worried that my seatpost is too short to raise it higher. Apparently, you need at least 2 inches of the seatpost length below the top tube for it to be safe.
10-30-15, 01:19 PM
#4310
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Yeah, I figured either C.E. or M.E. Anyways, I agree entirely that by inserting the seatpost just a couple of inches into the seat tube will greatly reduce the local bending moment in the seat tube. Sometimes seemingly elegant solutions such as this are not always the best from an engineering standpoint.
10-30-15, 08:52 PM
#4311
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Brian from Circle A Cycles, now just Chapman Cycles, made two bikes like this with the integrated seatpost. One was my track bike which has been posted here before and another was a cross bike with similar routing through the seatpost. Atleast on mine I have cut the post so that it extends only about 1.5-2 cm past the slot for the pinch bolt. I figured any longer and it would cause more stress on the tube itself. The butting on this specific tube is pretty thick and is also sleeved by a lug at the toptube juncture. This particular bike has been ridden and raced a ton and has been mainly a messenger bike for five or six years now and is still in great shape.
11-01-15, 09:56 AM
#4318
Senior Member
11-01-15, 10:00 AM
#4319
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11-01-15, 11:40 AM
#4320
Calamari Marionette Ph.D
11-01-15, 11:42 AM
#4321
Calamari Marionette Ph.D
11-01-15, 07:12 PM
#4323
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I know what you're saying, but I'd lying if wasn't thinking about putting carbon post and a cool seat on my boy's Giant balance bike when I bought it.
