I currently am running a 58-46 2x setup on my Canyon Speedmax with an 11-30 cassette. I find this set up to be really solid for all the terrain I train on in Colorado but feel like I could get an advantage in racing by going going 1x.
I’m wondering what combo I could/ should run 1x? I’d probably be looking at a 60 or a 62t right? And what does that mean for a cassette? Can you run an 11-34 with that big of a front ring?
Also, what is a chain catcher needed with these 1x set up’s? Looking at the 60 or 62 D2Z or Digirit front ring.
You can definitely go with 11-34 Dura Ace in the back. If anything, the 1x system allows for bigger gear ratio in the back, because the chain doesn’t have to accommodate two different sizes in the front.
Also, I don’t think you need a chain catcher. The 1x narrow-wide teeth are really tall and I’ve had a chain drop once on a 56t front with 11-34t back for Shimano mix with d2z, and never dropped a chain on 52t Sram 1x with 10-33 cassette. Two different setups on two bikes, with roughly 5000km done on each.
As per the sizing of the front - I don’t know the answer for you. As an AG I can give up on pedaling over 65-70kmh. Can you? Check the online gear calculator for when you’d spin out over 110rpm with 62-11 or 60-11, and when you’d be grinding below 70rpm with 62-34 or 60-34.
Yeah I do find that I’m often on the flat or downhill in the 58-11. Anything with a tailwind I’m in 58-11. I run an average to below average cadence (prob around 75-80 rpm) at Ironman effort. If I was able to super tuck in the races then I’d stress about it less but just shrugging in the aero position isn’t worth not pedaling IMO.
I’ve plugged your numbers into my Challenge Roth course model (I haven’t added the gear calculations to other models) and set the speed to 44.2kph (~27.5mph) with a cadence of 85
Gear friction model based on frictionfacts testing
Assuming your cadence isn’t too different from 85, you will be in the optimum gears most of the time, hitting the 58-11 2.2% of the time
If you shift to a 62x11-34
Hitting max ratio 1% of the time and min ratio 0.2%
This would save you 0.36w of gear friction compared to current
Using aero data from when Premier bike testing 1x combined with the friction saving would give an advantage of 45s (22.5s for a 70.3)
11-30 would save 0.26w
a 60T with 11-34 would save 0.21w
So the optimum for this scenario is the 62x11-34
Obviously this kind of analysis is getting really specific, but I ran through some different scenarios to allow for course variations and the general principle held.
I just switched to a 1x for the first time and ran 58t + 10-33 (SRAM) for Mont Tremblant and it was perfect.
Check out “Sheldon brown gear ratio calculator†online that’s what I use. You can look at speed required at 80RPM.
It’s great for racing but you’ll want a training one too especially in boulder. It’s just too hard to climb in zone 2 in the 58-33… I have a 52t for every day use. You could go with a 60 or 62 and 11-34 I think, but the limiter will be the trade off. For a course like OSide or St G i would still be really tempted to stick with 2x setup.
You can definitely go with 11-34 Dura Ace in the back. ***If anything, the 1x system allows for bigger gear ratio in the back, because the chain doesn’t have to accommodate two different sizes in the front. ***
Also, I don’t think you need a chain catcher. The 1x narrow-wide teeth are really tall and I’ve had a chain drop once on a 56t front with 11-34t back for Shimano mix with d2z, and never dropped a chain on 52t Sram 1x with 10-33 cassette. Two different setups on two bikes, with roughly 5000km done on each.
As per the sizing of the front - I don’t know the answer for you. As an AG I can give up on pedaling over 65-70kmh. Can you? Check the online gear calculator for when you’d spin out over 110rpm with 62-11 or 60-11, and when you’d be grinding below 70rpm with 62-34 or 60-34.
Can you explain what you mean by that? Are you suggesting that 1x allows for a larger granny gear? Also, if your RD can handle the larger granny gear with a 1x at a given chain length, how would using a smaller small ring not also work?
Scenario 1:
52-36 front11-28 backchain has to accommodate anything between max length of 52+28+n and min length of 36+11+m (m>n, but not much) → the difference in higher
Scenario 2:
56 front11-34 backchain has to accommodate max length of 56+34+k and min length of 56+11+l (l>k, but not much) → the difference is lower
Scenario 2 has of course narrower gear ratio, but it’s easier to properly size the chain, keep its tension and adjust gearing.
Scenario 1:
52-36 front11-28 backchain has to accommodate anything between max length of 52+28+n and min length of 36+11+m (m>n, but not much) → the difference in higher
Scenario 2:
56 front11-34 backchain has to accommodate max length of 56+34+k and min length of 56+11+l (l>k, but not much) → the difference is lower
Scenario 2 has of course narrower gear ratio, but it’s easier to properly size the chain, keep its tension and adjust gearing.
Scenario 1:
52/11=4.73
36/28=1 26
Scenario 2
56/11=5.09
56/34=1.65
The 1x setups are popular on the flats for obvious reasons. Once you try to make it work on step climbs the small to big cog disparity requires a long cage derailleur. Electronic has the benefit of locking out gears, usually little ring/little cogs.
IMO the biggest reason for road 1x is than Sram couldn’t make a functional FD so just worked around it.
I agree with mathematics on the SRAM FD - it’s shit. In the same time I think the SRAM 1x aero plate is beautiful and functioning perfectly.
As per the gears - I don’t deny the 1x has lower bandwidth of gears. Of course. I simply state that a chain in 1x system has to accommodate that wider bandwidth of gears, which leads to inefficiencies and also easily dropped chains. Therefore, adding incremental cogs on the back of a 2x system (e.g. increasing cassette from 11-28 to 11-34) will have a worse effect than adding the incremental cogs on the back of a 1x system, which won’t be as bad. That’s what the author asked in his first post.
IMO the biggest reason for road 1x is than Sram couldn’t make a functional FD so just worked around it.
Only people who don’t actually use SRAM FD’s say this. It is a lie. (Though I get that your role on this forum is basically to troll. :).
It works fine enough if you keep the exact 13 tooth gap. Go more than a couple teeth outside that and it’s miserable. I’ve had Shimano set up on a ridiculous 52/32 and it was slower to shift but never rubbed and never dropped. Something I can only say for Sram with stock chainrings at their preferred ratio
Therefore, adding incremental cogs on the back of a 2x system (e.g. increasing cassette from 11-28 to 11-34) will have a worse effect than adding the incremental cogs on the back of a 1x system, which won’t be as bad.
If you look at the friction graphs I posted earlier you’ll note that the friction of adding larger cogs at the back is worse on 1x, because the small chainring is better aligned with the larger cogs on the cassette for 2x.
1x offers an efficiency gain if you can plan your gearing such that you spend the majority of your time in that dip in the friction graph, where 1x is better than 2x.
