Nothing fancy but I like the Jandd bags...think the ones I use are called mini mountain wedge bag or something...can fit two tubes, co thing as well as a couple of cartridges, irons etc...no velcro via chaffing and just a strap under the rails...actually, I think it has a velcro seat tube thing but I just cut those off...really durable as well...cheap enough too...they will even do a special order if you want certain colors to match frame or whatever if I remember right for not much more...good company and good simple bags...lifetime warranty as well...
https://www.jandd.com/detail.asp?PRODUCT_ID=FMMW