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I've been reading this forum for the better part of a year now, and as a senior in high school, I'm building a rigid 29er for my CADD project. I'm basing my jig off of an extrusion I-beam design. I've haven't had access to my drawing at school, so I've attached a scan of a previous printout. I know the 2nd top tube doesn't do anything, but from what I read as long as the down-tube is ample it won't hurt. For the miters I was planning on using a hole-saw to get close, and then hand filing. I'll be riding it for cross-country trails here at Bootleg Canyon and in the Golden/Denver area when I go up to school. I'm about 6'5" and 240lbs.(without gear).
I rode various 29ers at Interbike, so I based the geometry somewhat off of what I liked about those and with what I have and like, a demo 7 and a 24" bmx bike(that'd I've been using for the cross country trails). It will mostly be used for cross country but also messing around(doing wheelies around campus and what not). So what I came up with:
Head tube:130mm(68/69 angle)
Effective Top Tube: 635mm
Seattube:500mm(74 angle)
Chainstay length: 450mm
Bottom bracket drop:66mm
Wheelbase: 1160mm
I plan on using a 470mm atc fork with 38mm rake
The thing I might want to change is the chainstay length. I think it would probably be better for me shorter, but I'd like to use straight gauge 7/8" with a single bend, so I'm not sure how short I can get them like that to still have clearance for a larger tire. I plan on running a 1x9 gear setup. It will most likely be TIG welded by a professional that has been welding for a long time and has done a few bike frames in the past(the founder of Redline actually worked for him for a while) so I'm not worried about heat control but I'm not sure about tube thicknesses and changes to geometry I may want to make.
Thanks,
Aaron
I rode various 29ers at Interbike, so I based the geometry somewhat off of what I liked about those and with what I have and like, a demo 7 and a 24" bmx bike(that'd I've been using for the cross country trails). It will mostly be used for cross country but also messing around(doing wheelies around campus and what not). So what I came up with:
Head tube:130mm(68/69 angle)
Effective Top Tube: 635mm
Seattube:500mm(74 angle)
Chainstay length: 450mm
Bottom bracket drop:66mm
Wheelbase: 1160mm
I plan on using a 470mm atc fork with 38mm rake
The thing I might want to change is the chainstay length. I think it would probably be better for me shorter, but I'd like to use straight gauge 7/8" with a single bend, so I'm not sure how short I can get them like that to still have clearance for a larger tire. I plan on running a 1x9 gear setup. It will most likely be TIG welded by a professional that has been welding for a long time and has done a few bike frames in the past(the founder of Redline actually worked for him for a while) so I'm not worried about heat control but I'm not sure about tube thicknesses and changes to geometry I may want to make.
Thanks,
Aaron
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