Tri bike that will be ridden in flat as a board area. I’ve looked at the gear ratio stuff but looking for some opinions.
Based on the time I spend in northeast Florida - 50 miles around Amelia Island with less than 400ft of climbing… I think the 48. It’s a little bigger than a 52x11, so high speed is covered. The 48x28 will be lower than the 52x25 that I need to get over the Intercoastal and not get dropped on the Saturday morning ride - when I’m in shape. Which is not now… If you find the 48x28 is too easy, you could swap to the 10x26 cassette, but only the two easiest cogs change.
I had my TT bike set up 1x11 with 50 x 11-28 for a flat 70.3. I could spin out the 50/11 on flats with a tailwind at race pace. I’d go with the 50 to get you a little more in the middle of the cassette more often and have 50/10 as an “overdrive”. I never went into the 50/28, I think i might have went into the 50/22 when i was on a false flat with a nasty headwind. But it’s nice to have some bailout gears, especially in training when you are trying to just have a recovery ride.
I had my TT bike set up 1x11 with 50 x 11-28 for a flat 70.3. I could spin out the 50/11 on flats with a tailwind at race pace. I’d go with the 50 to get you a little more in the middle of the cassette more often and have 50/10 as an “overdrive”. I never went into the 50/28, I think i might have went into the 50/22 when i was on a false flat with a nasty headwind. But it’s nice to have some bailout gears, especially in training when you are trying to just have a recovery ride.
50/11 at 90rpm is 32mph. At 110rpm, which is closer to spinning out, it’s 40 mph. I think hardly anyone else here is doing that on flats with a tailwind unless it’s a hurricane. lol
I had my TT bike set up 1x11 with 50 x 11-28 for a flat 70.3. I could spin out the 50/11 on flats with a tailwind at race pace. I’d go with the 50 to get you a little more in the middle of the cassette more often and have 50/10 as an “overdrive”. I never went into the 50/28, I think i might have went into the 50/22 when i was on a false flat with a nasty headwind. But it’s nice to have some bailout gears, especially in training when you are trying to just have a recovery ride.
50/11 at 90rpm is 32mph. At 110rpm, which is closer to spinning out, it’s 40 mph. I think hardly anyone else here is doing that on flats with a tailwind unless it’s a hurricane. lol
I should add the caveat, that I do not spin anywhere near 110, or even 100 rpm. My comfort range is 80-85 and I greatly dislike spinning over 95. YMMV. Also, on flats raw power output (or W/CdA) or much more important so if the OP is a lower power rider, this may not be an issue.
The OP is not a low power rider. 
The OP is not a low power rider.
Ha! Then my advice stands…
Tri bike that will be ridden in flat as a board area. I’ve looked at the gear ratio stuff but looking for some opinions.
What did you end up going with?
50t
.
What are your thoughts in running the 50t front with best rear combo?
Was looking at charts last night the 10-26 and 10-28 still seem to have a pretty good range
Went with a 10-28 cassette.
The only small PITA is starting from a dead stop with a 50t after years and years of being used to shifting into a small ring. Not a big deal though.
A 1x makes sense and is a nice solution for flat land riding. There’s no way I’d use it in hilly terrain though. A steep and long uphill would be punishing.
Think I will plan on training with a 10-33 and racing on a 10-28, not much difference btw a 10-28 and 10-26 main gearing is identical. I run 54/42 with a 11/25 or 11/28 for the vast majority of my riding now, so I dont think I lose a lot in terms of ratios. Unless you can provided me with more insight, this is what I have gathered from my one night of research.
I saw that some of the stores online sell the 52T SRAM RED AXS Power Meter Kit, does anyone have it on their bike or is it considering the upgrade?