B2B weather question

Look at forecast and compare it to what you wear when you ride in those temps.

I didn't do B2B but IMFL and it was in the 40s on the start of the bike. From riding, I knew what I would normally wear:

leg warmers, arm warmers, windproof vest, light jacket over so when I took it off still have vest on, wool socks, headband, bike gloves with disposable stretchy gloves over I could toss. 

I get cold and riding when cold I'm miserable....so I dressed like what I would wear.

During bike I threw away stretchy gloves and took of light jacket and pushed up my arm warmers. Light jacket I found for about $25 and it could be pushed into a pocket as it was highly packable.

I look for cheap tri or bike gear and buy it with the idea I can toss it at an aid station if I don't need it.

Last year for the B2B half, I wore a tri top, tri shorts and arm warmers and fingerless bike gloves on the bike.  I also put a gallon size zip lock under my top for the bike.  I dumped the zip lock at the first bottle drop.  I took off the arm warmers during the bike and left them in T2.

For the swim I wore a sleeveless wetsuit, no booties or cap.  I was absolutely fine in the water.  Feet got cold running to T1.

No offense to folks above because everyone is different but I wore way less on the bike and run than some others and was fine. Here are my thoughts...bulleted just to be fancy:

• Numb feel from walking TO the swim start. Suggest some cheapie flips flops because 40 degree sand hurts.
• No issues running across the tarmac after the swim. Got chilly on the swim though in a full wetsuit, but peeing in it warmed me up!
• Rode the first part in a tri top and long sleeved bike jersey (so 2 layers), no gloves, no booties and tri shorts. Shivered for 2 miles and then was comfy for 30 and too warm until special needs. Dropped the long sleeved jersey at special needs and rode in tri top and shorts the rest of the way and was fine. It was a lovely day for a ride actually! 60ish and sunny.
• Run: Chafed badly on the swim (forgot body glide) so tri top was rubbing. Switched to a tech t-shirt at special needs (I did the full) and took a long-sleeved tech tee for later in the race if needed. A dry, comfy shirt felt like HEAVEN halfway through that run!

Hope that helps. Good luck with your race. Remmeber, this is all for last year...the weather changes. I'd suggest paying careful attention  to what you ride in over the next couple of months as the weather cools off and try to tailer your race day stuff to what works for those conditions in training.

Louis

I've done Fall marathons past couple years.

Does everyone dress a bit warmer for IM run leg vs stand-alone marathon?

I think it depends when you expect to finish. If you run a 4hr marry, you're done when it is, presumably sunny and nice. If you do a 12hr IM, you are running a chunk of that in the dark.

No 4hr time here! Prob more like Gallowalking 5hr + for run leg.  Last Fall's marathon was cloudy, breezy 28F at the start and overcast 38F at the finish.  Ran that with long sleeve base layer & short sleeve jersey on top, jersey gloves, knit cap, & running shorts.  I survived OK where several lighter-clad elites were dropping from hypothermia ~15-20mi mark. Must admit that the space blanket at the finish was very welcome. 

Hoping this year's B2B run might be a little warmer than that one!

Can't remember what the temps were at the finish but it wasn't too bad. But then again, late October could mean anything. You're gonna like B2B...really nice race. Don't let all the logistics and all that worry you- it all becomes fairly clear as you go along :-) And 38 degrees would be VERY abnormal for NC in late October. Usually my kids are trick-or-treating in just their costumes (no jackets or anything like that)..cool, yes, cold, no.