For many flats courses i train and compete on i never use the small chainring or the biggest rear cog. I have a pretty Good FTP, around 370w for 60min in TT position @84kg. So even in my long rides i seldom go below 250w. So in rides with no steep hills i mainly use the big ring and the smaller cogs.
For saving a couple of watts of aerodynamic drag, is it ok to remove the front derailleur and attatch a aero-chain guide? Or will the 2x big ring and the prescence of the inner ring make This Worse than a real 1x setup with just one ring made for 1x setup?
If i am not planning to use the large rear cog, will the chainline be problematic?
Or should This be done the real way, buy a 1x ring and remove the small ring etc.?
in your case, you can just ditch the inner ring and f-der.
(no need for a chain guard; I can count on the fingers of 0 hands the nr. of chain drops when not shifting the front …)
while your at it, you might even remove the bigger rear cog cluster and replace them with some spacers! (limit your r-der though!
and then to improve chainline, you could add an additional 12T cog to move all cogs one position to the centre! (so 11,12,12,13,14,15 etc
The very very best case claims I have ever seen about the benefits of 1x put it at 2.5-3 watts better than a derailleur and 3.5-4 watts better than if you are willing to dremel off the hanger as well as removing the derailleur. AeroCoach Affix 1x aero chain guide (aero-coach.co.uk). I have no idea how these numbers were derived, they clearly are part of a marketing pitch, and I have seen others claim the gain is more like 1-2 watts even after taking a dremel to the hanger. Ultimately if you are going to do this you need to do it right because the gains you are chasing are sufficiently marginal that they aren’t worth it if you add other headaches by bodging the system.
Doing it right means optimizing the chain line and using a 1 by aero- ring. Any number of company makes such rings that go on a standard crank but mount in the proper 1x position. We are talking differences of <1 watt but 0.3 watts isn’t implausible which could be ~30% of the gains you make by going 1x.
In terms of chain guides it really does come down to the hanger. Personally I couldn’t get rid of my hanger because there are situations I want to be able to use 2x and on my frame that means the hanger has to stay attached. However the pursuit of ultimate speed requires sacrifices and so people do take them off and then get maximum benefit by not running a guide.
It takes me all of 5 minutes to swap my bike over from 2x to 1x to do a TT race.
Therefore IMO there is zero reason to have my bike setup for 1x to train. I realize you say you live somewhere flat and never use the 2x really but honestly a 56T in a realistic slow gear is going to stop being a usable line around the 23t. It’s so flat there that you never go slower than 18mph? Even briefly?
I mean I guess so if you want to.
I’m not a stud power wise. I run a 56/42 because locally we have hills where I cannot stand spinning high cadence downhill while in the aerobars. I prefer a comfy cadence that feels safer. Hence my choice even if I only use the super fast parts of the gears once in a while.
60% recovery power for your high ftp would still only be 210w for a “rest” between intervals. 210w and a 56 means being in some of the bigger sized slow rear cogs. I just prefer the 2x for stuff like that. Also if I put the bike on the trainer for Zwift, having the 2x is nice.
Do yourself a favor and just go with the proper 1x route. It’s not difficult to swap and all things considered a 1x ring is quite cheap. I race on one of these Garbaruk 1x rings, but have bought a few of these ebay specials as well. Both work great. If you went with your 2x ring, you would absolutely need a chain guide but thats basically like having a FD. I’ve never used a chainguide with a proper 1x ring on both my road and tri bike for ~3 years and have a total of 1 dropped chain which happened during a speed wobble in the highest gear.
Do it. You don’t need a chain guide. In ~10 years of riding 1X, I’ve only dropped the chain once in a race – and with a 1X setup, it’s really easy to slip it back on.
I have an 11-36 in the rear and 48,50,52,54 chainrings that I periodically swap out as needed. The 48 allows me to pedal 80rpm at 8mph and still go 34mph at 100 rpm, which covers any TT I’d want to do. The only reason I use the other chainrings is that I like to stay in the center of the cassette for flat TTs.
I recently took the hanger off my P3; I’ve only done one field test so far, so it’s inconclusive. But that change by itself may be in the 3 watt range. Go figure.
For me, the big gain for this setup came from the switch to a track crank, which yields a much narrower q-factor. That’s more like a 10-15 watt improvement.
Thank you all for your answers. Seems that it is no definitive answer for this one.
I think i will go for a 1x plate and try it out, maybe a 54t.
Will i need some special bolts for mounting one 1x chainring with no inner chainring, and how do you place the chainring the way it should regarding to the distance from the crank (to avoid to big chain angles)?
Do it. You don’t need a chain guide. In ~10 years of riding 1X, I’ve only dropped the chain once in a race – and with a 1X setup, it’s really easy to slip it back on.
I have an 11-36 in the rear and 48,50,52,54 chainrings that I periodically swap out as needed. The 48 allows me to pedal 80rpm at 8mph and still go 34mph at 100 rpm, which covers any TT I’d want to do. The only reason I use the other chainrings is that I like to stay in the center of the cassette for flat TTs.
I recently took the hanger off my P3; I’ve only done one field test so far, so it’s inconclusive. But that change by itself may be in the 3 watt range. Go figure.
For me, the big gain for this setup came from the switch to a track crank, which yields a much narrower q-factor. That’s more like a 10-15 watt improvement.
Are you on an SRAM road rear derailleur for to accommodate the 36 or Shimano Mountain for your 36 ? Thanks for the input as I am trying to decide on exactly this 48 with 11-36 combo. My engine is somewhat smaller than yours though, but for the races I am doing it should suffice.
I run a 1x setup with a N/W ring, have for years. I thought I would try a standard ring once on a training ride, dropped a chain within a block of the house. Put the 54t N/W ring back on, don’t give it a moment’s thought anymore.
Will I need some special bolts for mounting one 1x chainring
I mounted a 1x (narrow/wide) chainring this summer, out of curiosity and yes, you should order shorter mounting bolts. Luckily I had some already that fit, which was good because the darn bolts are almost as expensive as the ring. I managed to order from a company in Taiwan, as I refuse to order from China.
Are you on an SRAM road rear derailleur for to accommodate the 36 or Shimano Mountain for your 36 ? Thanks for the input as I am trying to decide on exactly this 48 with 11-36 combo. My engine is somewhat smaller than yours though, but for the races I am doing it should suffice.
SRAM Wifli. Technically only designed for 32, but works with 36.
Are you on an SRAM road rear derailleur for to accommodate the 36 or Shimano Mountain for your 36 ? Thanks for the input as I am trying to decide on exactly this 48 with 11-36 combo. My engine is somewhat smaller than yours though, but for the races I am doing it should suffice.
SRAM Wifli. Technically only designed for 32, but works with 36.
Thank you all for your answers. Seems that it is no definitive answer for this one.
I think i will go for a 1x plate and try it out, maybe a 54t.
Will i need some special bolts for mounting one 1x chainring with no inner chainring, and how do you place the chainring the way it should regarding to the distance from the crank (to avoid to big chain angles)?
Bottom bracket spacers for whatever type BB you have. I would not necessarily follow the standard guidelines, but rather center on the gear range you think you’ll use most.
For me, the big gain for this setup came from the switch to a track crank, which yields a much narrower q-factor. That’s more like a 10-15 watt improvement.
For me, the big gain for this setup came from the switch to a track crank, which yields a much narrower q-factor. That’s more like a 10-15 watt improvement.
I wanted to discuss the logic of legs being more narrow resulting in lower drag.
Hear me out of a second. Unless you can literally glue the legs together, each leg is a separate object to the wind as is the bike.
So whether the legs are close together or far apart they generate the same drag to the wind since we cannot chang the shape of each leg.
The bike in between the legs should also be a separate airfoil, if not you would want a BB drop of 12 cm such that your cranks barely clear the ground for TT’s because the gains should be greater being both more narrow to the wind with legs and more bike between legs (instead of high up).
So are you saying the the closer you can get to the bike with legs, you make the legs + bike turn into a single airfoil to the wind versus three different shapes to the wind that add together and that single airfoil has less drag than three airfoils added together. When I get into a tuck, I pull knees together to top tube to try to make it all one airfoil and put as much bike between my legs as possible by sitting on top tube, but this is not pedaling on a bike. That’'s just coasting on the bike. Are you saying your narrow stance width (and I think we should not confuse stance width and Q factor since yuo can have narrow Q factor and end up with wide stance with long pedal axles and shims) basically makes your legs + bike look closer to a supertucker to the wind:
I have done the testing on skis with no bike and legs closer together seems to be slower. I believe this is because there is a lower pressure area behind two legs that messes with airflow, but behind two single legs the air can more easily reattach. But there are just two indepedent cylinders with no bike in between.
But the entire idea of narrower downtube bottles suggests you don’t want to fill the gap between legs and bikes and you want to keep legs and bikes independent airfoiles. If not, you’d fill the entire gap between legs with the widest deepest airfoil that would make the three all one virtual airfoil.
