Background: High level AG biker on 70.3 and 140.6, most aero upgrades on the bike is already bought. FTP around 375w in the TT-bars. So i am not looking for the “go back and train for those watts in stead” answers. I had 5s up to the next athlete in Copenhagen on the total time, so these margins matters to me
Bike: Argon 18 E118 Tri+ Disc with Shimano 12 speed
This year i have used a 56t front ring from Pyramid chainrings with a 1x setup and 11-30 cassette on the rear.
The competitions this year have been rather flat (Elsinore and Copenhagen). None of the hills in those bike legs have been an issue with the 1x setup.
Compared to using a front derailleur of the newest Ultegra 12 design (rather small derailleur) the aero benefits of going for a 1x setup can´t be big. 2-3 watts at 45kph? I averaged 41,9kph in copenhagen for reference.
Reading the data from ceramicspeed regarding 1x and drivetrain friction got me thinking. The small and big sprockets seems to have a larger friction increase than the potential aero benefits.
Will 1x still come out on top given that you choose a chainring size that makes you stay most of the time around the middle of the cassette and avoid the biggest (crosschaining) sprockets and the smallest (friction) sprockets?
Or should i just abandon 1x for competitions? I run 2x now off season to have an easier time while training.
I understand that this will vary with course and other factors, but still happy to hear your thoughts!
There is so much that goes into it aerodynamically that the only way to tell is to test. The loss of the FD is somewhat cancelled out by the long cage of the RD.
As far as drivetrain efficiency goes, the first and most important step is to keep your chainline as straight as possible.
As it seems like you train very hard, I am going to assume you have both a crank based power meter and a smart trainer. You can test this for yourself by double recording on both the crank and trainer. Don’t worry about the absolute numbers, but the difference the meters show with different gears. Like a 52/21 vs 39/15 (two gears that are similar in length, but different chainlines). If you’re meticulous about it you could conceivably know the watts lost for every gear on the bike at a desired power output.
I spent way too much time adding that Ceramicspeed data to my course models, using the IM Florida (flattest one I’ve got) model:
Per Premier tactical testing, the aero advantage of 1x would be 44s at your speed over an IM
At a cadence of 85 with a 155mm crank you would spend all of your time in one of the lowest friction combinations of your 56, 11-30
A 58 would save you 0.1w = 2s
A 58/44 would give the same saving and a wider gear range for normal use.
In the scenario you’ve presented 1x is the fastest based on available data, it doesn’t work out so convincingly for hilly courses or slower athletes (or SRAM)
I have never measured the difference, but is a 1x ring placed closer to the crank than the big ring on a 2x? To reduce cross chaining in the big sprockets? That will surely increase the loss in the smalls sprockets as well. Even with the 56t front ring i find my self often using the smaller (trying to avoid the 11t) cog.
My bike was set as 1X before. Range is never an issue as the wide cassette can give you the range of gears required. What I really disliked was the gap in gears. I am very picky about my cadence and I dislike feeling in between gears. One gear legs are spinning too fast, the next gear too slow.
I am now an happy man with a 50-34 crank and 11-25 cassette (11s) with very little holes in it.
That is the wrong question. A 50/34 with 11-25 on 155 cranks gives harder gears than a 53/39, 11-28 on 170mm cranks
You need the whole picture to evaluate those cog choices
That is the wrong question. A 50/34 with 11-25 on 155 cranks gives harder gears than a 53/39, 11-28 on 170mm cranks
You need the whole picture to evaluate those cog choices
Fair enough - What are you racing, and Where are you racing, that you need a 34 x 25 ??
I ran a 1x 60t PCD chainring for much of the year. Could have probably gone for a 58t but this is what I had in the inventory. Averaging around 30 mph~50 k/hr for most flat crits and TT’s it wasn’t great for Zwifting or gentle rolling around in warm ups/cool downs but I liked racing on it.
I think if you’re under the 14t or at either extreme of the cassette the friction is enough to eclipse whatever potential savings you might find. But in both events I used it for this year, I’m not racing in the small ring anyway.
That is the wrong question. A 50/34 with 11-25 on 155 cranks gives harder gears than a 53/39, 11-28 on 170mm cranks
You need the whole picture to evaluate those cog choices
Fair enough - What are you racing, and Where are you racing, that you need a 34 x 25 ??
I haven’t race in a while now, but I ride my bike everywhere. I like having the right gear if I feel like climbing. And since I use my bike also indoor on 3 rollers on Zwift, this makes me even more cadence sensitive. I’ll take the extra weight on the bike for that comfort.
I only race my TT bike on flat courses and most of the time they end up being out and back (with one way having a tailwind)
Because I’d spin out my 53 (and I’m in the smallest cog in the back), the only economical answer to get more gears was to go w a giant ring up front, 1x to keep myself in the center of the cassette at a reasonable cadence when I’ve got that tailwind. From there the only question was: a 56, 58 or 60? I went a 60 just because bigger is better =)
Even if there were slight aero / friction losses, I’d imagine the setup we both run is optimal given a 2x doesn’t go as big up front as you probably need
I only race my TT bike on flat courses and most of the time they end up being out and back (with one way having a tailwind)
Because I’d spin out my 53 (and I’m in the smallest cog in the back), the only economical answer to get more gears was to go w a giant ring up front, 1x to keep myself in the center of the cassette at a reasonable cadence when I’ve got that tailwind. From there the only question was: a 56, 58 or 60? I went a 60 just because bigger is better =)
Even if there were slight aero / friction losses, I’d imagine the setup we both run is optimal given a 2x doesn’t go as big up front as you probably need
I do the same on my TT bikes–either a 58 or 60 up front, and an 11-28 out back. I rarely every will use the 11 or 28, viewing them mostly as spacers. My chain line tends to be good.
What often is missing in conversations like these is that for some rides, a very low cadence tends to work well for them. Not every works optimally at cadences in the 80s or 90s.
I do the same on my TT bikes–either a 58 or 60 up front, and an 11-28 out back. I rarely every will use the 11 or 28, viewing them mostly as spacers. My chain line tends to be good.
Pretty much the same. 56 front, 12-23 10x rear, and also using the outer cogs mostly as spacers - but I’m almost 76 years old and race in Florida (flat). The 56 chainring has wide/narrow teeth and works well without a chain guide, no clutch in the derailleur. Next thing I’m going to try is a 11x chain.
