with the right contact points almost any body position can be achieved. It will probably by fugly as hell, and may not handle very well, but it is possible.
Caveat that this may only possible on traditional bikes with rounds seatposts and steerer tubes that open up the full range of aftermarket options.
What you are describing was exactly how the tri bike was born. Many early converted frames did in fact look a little crazy until purpose built steep seat angle bikes began to be developed. Tube shape is a secondary thing to proper geometry for purpose. Something I am finding interesting is that now that the weight of aero bikes can get down to the UCI weight limit we saw pros using full aero machine on some of the steepest climbing stages of the Tour. This in a way reinforces what I feel that you are saying and I am attempting not further clarify, that it’s geometry. What I mean is that the major difference between a climbing race bike and an aero race bike is tube shape. The geometry is the same for all race bikes within a narrow range of head and seat angles. Aero bikes climb just fine they just tend to weigh a bit more but these days if you have the budget they can be built pretty light without Gucci parts.
That’s not surprising. You can get a disc brake road bike with expensive, but standard parts way below the 6.8 kg limit. Canyon sold a ~6.0 kg disc brake bike something like 5 years ago, Specialized sells the Aethos. That easily leaves you with >= 800 g to add aero features, which doesn’t seem too hard.
The 6.8 kg weight limit is yet another rule that promises “safety”, I guess, but hasn’t kept up with the times.
It isn’t that simple. You cannot move all contact points by the same amount, and this means you cannot achieve the same body position exactly. The cranks are fixed, and changes in the saddle position are relatively small. You have the biggest leeway with stem length and handlebar width.
In my case, the proper sporty fit on my endurance road bike was achievable, but it forced more rotation of my back, which put more pressure on my perineum. I tried to rotate my saddle forward, which led to me sliding off of it, and buying new saddles with cutouts (which helped somewhat, but still isn’t as good as my more aggressive road bike).
Moreover, even when you achieve the same fit, you will have different centers of gravity, which leads to different handling and a different ride feel.
A saddle can be moved back and forth 50-100mm with standard rails and changing between layback inline and straight and even a layback seatpost fitted in reverse.
If you weren’t able to get a “sporty” fit on your endurance bike that’s by design of the manufacturer fitting parts with limited range of adjustment to sell more bikes.
Agree to a point, but it does depend on what position you are trying to achieve and the limitations of the bike you are trying to achieve it on. Geometry isn’t always as limiting as some make it out to be when it comes to fit. You can often get an aggressive position on an endurance bike or a relaxed position on a TT bike. I’m not saying you can always get the fit you want on dramatically different bikes, but it’s often doable. Particularly if you can play with frame size and have different seat post options. For years, I rode Specialized Tarmacs and Roubaixs. I’d ride a 58 tarmac and a 56 roubaix with the exact same position even though the frames had very different geometry. That’s all from a fit perspective, geometry certainly has an effect on handling. And if you are going down a couple frame sizes to make a bike fit the way you want, that can dramatically change the handling (ie - super long/short stems change steering dynamics and F/R weight distribution). And I think that’s the big concern. You can always downsize a frame to get a more aggressive/forward position, but at some point you don’t want to be riding over the top of your front wheel (which is basically the feeling I get on any TT bike, but I accept that the handling sucks on those).
I agree with that, and in my case getting the fit right came with compromises like you mentioned. In my case the solution was to get a frame with a more aggressive geometry and shorter cranks. I run the stock stem length and stock bars 42 cm. The latter are decidedly old-school these days.
as somebody who DID have a power meter on both old bike and new bike. Van Rysel EDR Ultegra (2021 model) and Canyon Aeroad SLX 7 di2 (2024 model) ..
Below 30 kph there is not much difference, but still 1 kph on my favorite loop at the same wattage.
Above 30 kph there is a bigger difference, it goes up until 2 kph on the same wattage. And probably even higher if I went above 40kph but that is not a speed I regularly ride at lol.
I’ve done some calculations for myself. At my average speed of 30 km/h roughly 2% of my power is frame, 2% is wheels, 2% is cockpit.
I’m not much faster on my Tarmac than on my Roubaix. Hence I go for the comfort.
But at 40 km/h all aero components add up quickly.
Here is a great article:
Aerodynamics vs. Weight: What’s the Tipping Point for Pro and Amateur Cyclists? - Bikerumor
I think unquestionably they are faster. My Venge Pro is easily 1-2 mph over my Allez. My TT bike is at least a couple of mph more than the Venge. Tadej didn’t switch to this new superlight aero bike on a whim.
There has to be more to that difference than an aero frame. Going from 20 to 21 mph takes an additional ~25 watts. Going from to 20 to 22mph is over 50 more watts. And if were talking about going from 25 to 27 mph (more typical race speeds), it’s almost 80 watts to go 2mph faster. Even the bike mfg’s aren’t claiming numbers close to that. I’m not saying you aren’t seeing those a 1-2 mph difference, but there is no way an aero frame alone is going to make that difference. Different body position, different cockpit may, etc.
I’m a big believer in aero and the frame can make a difference, just not 1-2mph difference. You’d be doing really well to see a 15-20 watt difference between frames (~.5mph improvement at 25mph). TT bikes can see much bigger differences, most of that is the aero bars/position those bikes allow.
The Specialized Venge Pro is claimed to provide a 22-watt savings at a speed of 40 km/h (about 25 mph) when compared to a traditional road bike frame like the Specialized Tarmac SL4 of its era (around 2011-2013).
That’s for the frame. Factor the aero wheels and easily surpassing 25 watts.
Yep, that’s probably in the ballpark as best case (I bet that probably includes the more aero cockpit on the venge on top of the frame). But even saving 22 watts doesn’t get you a 1-2 mph benefit at 25mph.
Yep, there are all kinds of things you can do to save aero watts (wheels, skin suit, aero socks, cockpit, etc.). Aero wheels aren’t doing any more on a aero frame compared to a non-aero frame.
I’m not arguing against an aero bike, 15-20 watts from a frame is $ well spent in my opinion (much more performance gain per $ compared to optimizing bike weight). I mostly race gravel these days and it drives me crazy that the frames aren’t more aero optimized. I could say the same for XC MTB’s (even though we saw some aero fairings on forks this year, so maybe it’s coming).
Ok.
Not sure what model years those are but looking at the tour results between the specialized models it’s all fairly minor.
The venge vias rim is at 204w
The venge disc is at 207w
The venge rim (2015) is 216w
Sworks sl7 is 210w
Sworks sl8 is 209w
That’s not just for the frame, the 2012 tarmac did not have deep section wheels whereas the venge did. The aero gains from the wheels are part of that figure already.
Thanks for sharing, as I’ve always wondered if Tour magazine had tested my rim brake Venge.