Long Distance Competition/Ultracycling, Randonneuring and Endurance Cycling - Seat bag?

I'm training for my first century and need to get a seat bag to stash a spare tube, mini pump, etc.

I was planning on keeping my cell phone back there too, and since I figure I'll get caught out in the rain eventually was wondering if there's a waterproof seat bag that's actually waterproof.

Would it work just as well to get a regular bag and keep a ziplock baggie in it to throw the cell phone in should the weather get bad?

I keep my wallet and phone in a ziploc baggie. My Topeak (Lg) Aerowedge seatbag has ample room for repair stuffs, keys, phone, wallet and a couple Clif Bars and gels. I've never noted any water inside it, even riding through hours and hours of PNW rain.

I've been using the Jandd Mini Tookit Bag for years.

http://www.jandd.com/detail.asp?PRODUCT_ID=FMTKB

It's minimalistic with room enough for the spare tube, CO2 & chuck, levers, patches, some tape for sidewall gashes, and couple of hex's. I put all of that plus an ID slip and two twenty$ bills into a ziploc bag for xtra water protection and security (in case I do something dumb with the zipper, keeping the small stuff from bouncing out). I only mount the bag and carry the CO2 thing when I'm doing >100mi, otherwise the same baggie (sans the CO2) rides in my middle jersey pocket. I keep a small short pump made by Lezyne on each of the bikes. Using the bag for 'long' distances frees up the jersey space for energy bars and my long sleeve underthing when it comes off.

I don't like putting my key or my iphone anywhere on the bike and believe those should be on my person so they get jersey space. I always keep an xtra ziploc for the phone and other things I don't want wet if it rains.

Ortlieb makes some that are waterproof... I have the medium and the large. The medium is large enough for a century... with room to spare a light jacket or arm warmers or extra food.

http://lh4.ggpht.com/_0jkA5M3PGcY/RViblB5_ABI/AAAAAAAABE0/08PwW_CjOUI/s800/IMG_2599.JPG

I mostly use a Camelbak and my cell is inside it within a ziplock bag.

http://www.amazon.com/CamelBak-Rogue-70-Ounce-Hydration-Pack/dp/B000JNL5FM

On rides longer than 130-140mi, I may bring a small top tube mounted bag.

http://www.all3sports.com/product_info.php?pName=profile-design-epack-large

+1 for the Ortlieb. About the only waterproof one out there I know of. Do a search on saddle bags, I think we covered this subject recently.

I use a specialized wedge, and it works fine, and is expandable. I can fit two tubes, patch kit, allen keys, tire levers, ID and CC, cash, cellphone (wrapped in its own neoprene pouch for vibration dampening, and ziploc-ed). I still have room for keys, energy bars, etc. I have a frame mounted topeak road-morph G (so I don't need to store that).

As for weather proofing, I carry two grocery bags, or I pick them up along the way. Last week around the last 15 miles of a 3/4 century ride it started to rain. So I take grocery bag and cover the whole saddle B-17 narrow/and bag, tied it around the top tube, and rode home. Not a speck of water anywhere near the saddle or bag. I used the other bag to cover the top of the frame pump, since it is mounted on the bottom of the down tube.

I believe most bags are sufficiently waterproof, at least I've never had an issue with mine.

In addition to the saddlebag, I recommend you pick up a "bento bag," for easy access to small items (e.g. energy bars, gels):

http://www.topeak.com/mediafiles/products/1053/ http://www.topeak.com/mediafiles/products/1055/

Topeak makes one with a rain cover, one without. There are a couple of other vendors out there as well.

Wow, ask a question - get the right answer(s) the first time - just like the Internet always works!!

I just have a cheapo Performance (actually another brand but the same as the Performance) expandable wedge seat bag that cost me $12 bought about 9 years ago, and it still works great even though I have it stuffed to the max.