bike tire
arch451b- theory + design of steel + timber, fall 2018prof. marc sanabra
leila el-erian
challenges of a bike tire
the steel rim for the bike resists the tension forces of the spokes.
the rim would buckle about its weak axis, here the y axis.
additionally, the spokes are slender.
slenderness = Le/(sqrt(I/A)
the spokes are too long (Le) and are too thin -- the cross-sectional area (A) is too small. slender members buckle under compression, so for the tire to work, the system must not have compression.
the rim would buckle about its weak axis, here the y axis.
additionally, the spokes are slender.
slenderness = Le/(sqrt(I/A)
the spokes are too long (Le) and are too thin -- the cross-sectional area (A) is too small. slender members buckle under compression, so for the tire to work, the system must not have compression.
solutions to a bike tire - spokes
prestress loads
prestressing process involves adding tension loads equally around the bike tire. these loads must be larger than the largest service compresion loads
service loads
normally, a bike tire will be under compression at the bottom and tension at the top
final loads
once these loads are combined, the large tension loads from the prestressing process cancel out the compression service loads
once these loads are combined, the large tension loads from the prestressing process cancel out the compression service loads
solutions to a bike tire - rim
prestress loadsprestressing process involves adding compression loads equally around the bike tire to counter the prestress tension loads from the spokes
service loadsnormally, a bike tire’s rim will be under compression at the top and tension at the bottom
final loads
once these loads are combined, the large compression loads from the prestressing process cancel out the tension service loads
once these loads are combined, the large compression loads from the prestressing process cancel out the tension service loads
solutions to a bike tire - system
frame loads
spoke loads
equilibrium