Zipp changes the layup of their rims all the time even if there
*isn't* a change in the outer shape and/or model #. The current 303
rims are 44mm deep, and are heavier and stronger than the previous
38mm 303s. The 340s are quite old and I'm sure they have little in
common with the new 303 rims. For one thing, the tension limit was
80kg on older Zipp rims (now 100kg), so that should give you some idea
of their strength. The new shapes are also more aerodynamic.
*isn't* a change in the outer shape and/or model #. The current 303
rims are 44mm deep, and are heavier and stronger than the previous
38mm 303s. The 340s are quite old and I'm sure they have little in
common with the new 303 rims. For one thing, the tension limit was
80kg on older Zipp rims (now 100kg), so that should give you some idea
of their strength. The new shapes are also more aerodynamic.
