thirdcrank wrote:I don't think that frame size is the main factor here because wheelsize is the main factor. Unless your bike has unusually small wheels, the legs on the rack will have to be the standard length to clear the wheel and mudguards.
In my experience racks can and do have different lenght stays. For example and I learnt this the hard way, the Topeak Explorer Tubular Rack w/disc Mounts
height is ~ 16". It is claimed to be for 26" to 700C wheels. Now I appreciate this photo is from an recumbent but it illustrates my point.
Note the height of the clearance above the wheel.
Now I suspect the original rack is a Delta rack or of similar elk .... note the height of the clearance above the wheel.
BTW I have switched back to the original rack and the battery is mounted nicely now (sorry no photo as yet).Delta racks as an example
have a height range from 12.5" to 14.5", a two inch difference and actually product a size guide for their racks
which is based on the frame size.