Which bento fits shiv tri the best?
Why do you need a bento for a Shiv tri? Just use the Fuel Cell.
I keep my spare tubular,co2 and pitstop in there. Don’t like the bladder. Don’t want a behind the seat bottle either. Can’t use the frame mounted fuel cell because I have a bottle there.
Which bento fits shiv tri the best?
While we can’t claim to be 100% objective, we think this one, the US-made Speedpack 483, fits the best:
It can mount as shown, or it can also mount partially over your fuel cell access opening (so 1-2 inches more forward than pictured). And, with our special mounting system, the Speedpack 483 is still totally secure on your top tube. No slipping, sliding, or rotation of the pack. Zero.
This was my setup for IMLOU this year. I attached some magnets to the Xlab and my frame so I could open refill the bladder. 
So it’s held on by magnets?
Yes, and it held very well. I think I opened the bladder one maybe twice to refill.
Sounds like a good idea. I won’t be opening mine unless I flat
Check out the official Shiv thread. There is a description of Crowie’s solution posted in the past few days.
I’ll second the Dark Speed Works Speedpack 483. I mounted it back closer to seat to keep access to the fluid port. Finally gave up on my Fuel Cell after a third instance of it losing all my nutrition.
Just thought I’d post my setup (nutrition and parts) that I run for IMs.
**Parts: **XLab Mini bag stuffed in carbon Xwing: 1 tube, 1 tire lever, 2 CO2, zipp valve extender and tool. Also 1 extra tube under saddle.
Nutrition: Using torpedo mount and Stealth Pocket, I’m able to carry all my solid nutrition I need for IM.
Stealth Pocket can’t be any more drag than a water bottle up front
This was my setup for IMLOU this year. I attached some magnets to the Xlab and my frame so I could open refill the bladder.
I use the same position for my DSW bag (right behind the cables). Using double sided tape to hold it in place. I don’t use the bladder though (just a BTA bottle).