Having a Specialized Diverge Carbon Di2 Gravel Bike, any suggestions on how I might be able to modify for an IM 70.3 race so that I don’t need to get a tri bike? Tires, aero bar?
Thanks
I would assume it has some tyres that are more specific for gravel riding, so I’d be looking to swap them out with something made for the road (GP5000s would be a good shout).
I’m not sure if the bars will allow it or not, but you could always try and stick on some clip-on aero bars.
Might be good to swap a higher geared cassette on there as well since you’ll be at road speeds instead of gravel speeds
.
LegendJeff has a good point with the gearing, but I’m guessing you already have an 11 tooth cog, so hard to go smaller.
Do you have a 1x or 2x? Diverge Comp is spec’d with a 40t chainring and 11-50t cassette, I believe. That gives you a range of 26MPH to 6MPH @ 90 RPM.
Honestly, for a 70.3 that’s probably just fine - unless there’s a long gradual downhill that you’d want to be averaging over 30MPH, just coast the downs and use it as a chance to fuel.
If it’s a flat race, you could consider a tighter cassette, like 11-32, which would give you more options to find your ideal cadence & power combination.
I have a Diverge Expert 1x. If I were to turn that into a road bike, here are my suggestions:
- slick tires (but keep them tubeless)
- clip on aero bars
- gearing… how do you feel about your range of gears now, specific to the 70.3 course you want to ride? My Diverge 1x came with a 40TT front chain ring (I’m laughing at the above post about mph range… because this in no way accounts for % grade). My gravel riding is pretty hilly and my stock set up was such that I couldn’t do hills >10% grade (I can do 15% well on my compact crank 11x28 TT bike, so this pissed me off). I put a 36TT chain ring on so I could manage the hills better, but I sacrificed my gearing at speed. I spin out at ~25 mph. The 1x gearing irritates me quite a bit and I’m considering going with a 2x so I have more options.
Otherwise, the Diverge is a really fun bike and capable of doing a LOT of different things! Have fun!
Having a Specialized Diverge Carbon Di2 Gravel Bike, any suggestions on how I might be able to modify for an IM 70.3 race so that I don’t need to get a tri bike? Tires, aero bar?
Thanks
I have two Carbon Diverges. One is mechanical 2x and my newest is SRAM 1X. I really notice spinning out on the top end on my 1X, usually around 22 mph. If I had to use one of those bikes for a 70.3 I’d take my older mechanical 2X and run ContiGPs tubeless 700 x 30s. I tried aero bars on it when I first got it but never could get comfortable - too much reach and too low for my back.
Mine is a diverge expert carbon with SRAM etap axs, 1x12 with 11-50, 40t. The 42mm pathfinder pros do a really good job on all surfaces. Given how comfortable the bike is, it might be a great choice for a 70.3 with rough roads. Definitely would not be front of the pack, but might help with save the legs for the run. Good luck!
(I’m laughing at the above post about mph range… because this in no way accounts for % grade).
Yes, while 40x50 @ 90RPM is always going to be 6MPH, regardless of grade (ignoring downhill, of course) the Watts required to maintain that 90rpm is a different story! 6MPH, however, is a pretty good low end. Much slower and you might as well hop off and push the bike 
If you really want to explore the math, here’s a good calculator: https://www.bicyclegearcalculator.uk/derailleurgears.htm