I am 5'8" and around 230... I find plenty to fit at terrybicycles.com, mtborah.com or teamestrogen.com. Check Plus size clothing. On the teamestrogen site I love the Canari plus size jerseys.
For tops; JC Pennys carries an excellent line of fitness wear in plus sizes. While not cycling jerseys per se, they are of a nice light weight wicking fabric and fit well. For instance:
http://www.jcpenney.com/dotcom/activ...317025373M.tif.
The JCP site also has long sleeve options (although buy some arm warmers which is a good option).
If she likes to wear mountain bike shorts, what I do is buy a good lycra cycling short, like a Terry T-short and then buy a men's runner short (from say REI) that contains some polyester/spandex/lycra in it.
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Private docent led mountain bike rides through Limestone Canyon. Go to
letsgooutside.org and register today! Also available: hikes, equestrian rides and family events as well as trail maintenance and science study.