Never heard of 5.8s.

5.8 would be the front from 5.6 and rear of 7.8. Generally not sold in that combo. The deeper rear would be a smidge more aero.

Related question. I've been debating between the 5.6 and the 7.8. It's not really clear where the tradeoff is in terms of when one gets better as far as size of hills and speed. I suspect the overwhelming consensus from this group will be 7.8 for everything but HC climbs in the Alps but I have to think that there's a point where the 5.6 is a better choice. It would definitely be more versatile to put on my road bike.

Thanks!

on this... I recently sold my 7.8 (rim brk) and got 5.6 (disc) mainly for the versatility as I can use on my gravel or road bikes. I'm hoping I don't miss the 7.8s too much well the front to be exact because I really want a Roval 321 anyways for race days.. so the rear would be collecting dust. I will likely be doing my first couple sprint tris with the 5.6 combo unless I can find a good deal on said 321 by then.

I'm debating the same... 5.6 or 7.8 and could use some advice. I'm a 135lb female racing Nice and Kona (backdoor brag) next year so am worried about the weight for climbing and handling in the wind. My current wheel set is the old 6.7s which I've had no issues with on hilly or windy rides. Just wondering if the 7.8s are pushing the envelop of getting to be too much wheel for me for little additional aero benefit.

If you can buy them separately, I'd probably get the 8 rear and keep your 6 front. The bigger differential between front and rear will make you more stable in crosswinds and i doubt the 7 front will save you too much time. The weight differential is negligable

If you have no issues handing 6.7 .. I’d say 99% you would ok with 7.8. They are faster and I’d switch for the betterbraking alone. I only had one scary day with my 7.8 and my road bike.. 25+ mph gust.. there was nothing sudden but I could feel the front push hard and I got 40 pounds on you