1x still costing results

[oldpotatoe]

Originally Posted by Mark McM

I would think that when racing with a 1x, one would want to install a fairly aggressive chain keeper.

Wha?? Heavy, non-aero..ya nutz?? Besides, I doubt the sram lizards would even allow it cuz their 1by system is, ya know, such a good idea..

They likely had direct assistance from SRAM Techs at a level no one else does.

yikes!!

Man, it's hard to keep defending SRAM when Di2 never has these problems. Grr.

++

[Mark McM]

Originally Posted by vincenz

I just don’t understand why you would want fewer gears in a road race. None of it makes sense. Gravel, mtb, ok, but road, why?

It depends on the course. If the course is flat, a 1x could work just fine. I've been racing criteriums (which are technically lumped under road races) with a 12-23 cassette and a 53-39 crank - but since I never use the 39 chainring, it might as well be a 1x. I could probably get by with a 12-21 cassette, but they just don't make those (at least not since 9spd).

[batman1425]

Originally Posted by happycampyer

Are shorter chainstays a factor? It seems as if 1x divetrains work well on MTBs, which have longer chainstays. Is the chainring of a 1x where the inner ring of a 2x crankset would be? If so, isn’t the chain effectively “cross-chained” when in the top gear? I would imagine that poor chain alignment and chain slack are a bad combination.

I think this is most of what Sram said was the problem with the 3T bikes. Road geometry pushes 1x right to the edge of feasibility with the cross chain angles

[benb]

It's kind of amazing how much complexity all this stuff is pushing.

I'm not sure why a 1X bike can't just have a guard that completely prevents the chain from coming off the ring... "walls" on the inside & outside of the ring, a wraparound guard, etc..

But still.. does it weigh less? What's the advantage? It's an electronic kit, is the weight savings of losing the front derailleur offset by the batteries? If you have to start building up a guard on the crankset or a wraparound unbeatable chain catcher does that offset any advantages? 1X eliminates 1 battery in eTap I assume but a traditional group doesn't get weighed down by any batteries anyway.

Is there an aero advantage?

If the course is flat enough for the reduced # gears to work, does any weight savings become pointless? Do the aero advantages (if any) outweigh the increased drivetrain losses?

For my riding style a flatter course or rolling course is more annoying to me if the cogs are spaced further apart. So for 1X to work for me I'd really have to know the bike wasn't going uphill and downhill much at all and I could get by with 12 closely spaced gears. This stuff with a massively spaced out cassette to equal a 2x9/2x10/2x11 drivetrain's range wouldn't work for me I think.

[Mark McM]

Originally Posted by batman1425

I think this is most of what Sram said was the problem with the 3T bikes. Road geometry pushes 1x right to the edge of feasibility with the cross chain angles

The numbers say differently. There is no difference in chain angle between the large chainring and the 2nd largest sprocket (or between the small chainring and the 2nd smallest sprocket) on a 2x, than between the chainring and either largest or smallest sprocket on a 1x.

[batman1425]

Originally Posted by Mark McM

The numbers say differently. There is no difference in chain angle between the large chainring and the 2nd largest sprocket (or between the small chainring and the 2nd smallest sprocket) on a 2x, than between the chainring and either largest or smallest sprocket on a 1x.

This may be true but 1x systems seem much more sensitive to shorter chainstay length at the limits, and most road bikes are right on the limit of length minimums. This was discussed at length with Aqua Blue's 3Ts. Another potential exacerbating factor are the narrow wide rings. Smaller tolerance for each link to line up laterally correctly due to the tight fit on the tooth and. Smaller tolerable margin of misalignment for each link with the ring. At extreme angles, this may result increased risk of a link missing all together and dropping - particularly at high loads, bumpy roads, during a shift, etc - like in race scenarios.

[shankldu]

Maybe I'm dumb by why wouldn't they use a simple ring on the front and back of the front ring / chain keeper to keep the chain from dropping ,seems a very simple cheap lightweight solution . Ah I see a guy above already said same, if it works on a mtb pounding thru the woods jumping logs etc it wil deff work on a road bike with the correct tension on the dr . Simple stuff really shocked that its even an issue .

Originally Posted by joosttx

Andy Schleck and chain gate.

https://youtu.be/cQK0eyi-zBA

[Mark McM]

Originally Posted by batman1425

This may be true but 1x systems seem much more sensitive to shorter chainstay length at the limits, and most road bikes are right on the limit of length minimums. This was discussed at length with Aqua Blue's 3Ts. Another potential exacerbating factor are the narrow wide rings. Smaller tolerance for each link to line up laterally correctly due to the tight fit on the tooth and. Smaller tolerable margin of misalignment for each link with the ring. At extreme angles, this may result increased risk of a link missing all together and dropping - particularly at high loads, bumpy roads, during a shift, etc - like in race scenarios.

If this were true, why would SRAM specify that their 1x systems can use shorter chainstays their 2x systems? According to the SRAM Road Frame Fit Specification, 12spd 1x systems have a minimum chainstay length of 395mm, while 12spd 2x systems have a minimum chainstay length of 405mm.

[benb]

Originally Posted by batman1425

This may be true but 1x systems seem much more sensitive to shorter chainstay length at the limits, and most road bikes are right on the limit of length minimums. This was discussed at length with Aqua Blue's 3Ts. Another potential exacerbating factor are the narrow wide rings. Smaller tolerance for each link to line up laterally correctly due to the tight fit on the tooth and. Smaller tolerable margin of misalignment for each link with the ring. At extreme angles, this may result increased risk of a link missing all together and dropping - particularly at high loads, bumpy roads, during a shift, etc - like in race scenarios.

I'm wondering if on the road with 1X they are riding with a bad chainline more often.

2X and 1X may have the same maximum chain deflection but that doesn't necessarily mean the average chain deflection across the length of a ride/race is the same.

There is so much more coasting in MTB too, maybe a factor. And MTBs hit more bumps but have a ton more capacity to absorb the bump & also probably have longer cage derailleurs and other factors that might keep more tension on the chain.

[batman1425]

Originally Posted by Mark McM

If this were true, why would SRAM specify that their 1x systems can use shorter chainstays their 2x systems? According to the SRAM Road Frame Fit Specification, 12spd 1x systems have a minimum chainstay length of 395mm, while 12spd 2x systems have a minimum chainstay length of 405mm.

With 2x, you have to consider chain rub on the big ring when in the small ring which isn't an issue with 1x. I suspect this is why 1x has a shorter minimum chainstay.

My point is - these systems perform near flawlessly at the pro level in conditions that are worse in most arguable ways (CX and MTB) but seem to fall short in Road. The key distinction between the bikes in those disciplines (from the drivetrain perspective) IMO is chainstay length.

[oldpotatoe]

Originally Posted by batman1425

With 2x, you have to consider chain rub on the big ring when in the small ring which isn't an issue with 1x. I suspect this is why 1x has a shorter minimum chainstay.

My point is - these systems perform near flawlessly at the pro level in conditions that are worse in most arguable ways (CX and MTB) but seem to fall short in Road. The key distinction between the bikes in those disciplines (from the drivetrain perspective) IMO is chainstay length.

Guess we’ll have to see what Trek has on their bikes this Sunday and then next Wednesday. I’m betting they have 2by...

[batman1425]

Originally Posted by oldpotatoe

Guess we’ll have to see what Trek has on their bikes this Sunday and then next Wednesday. I’m betting they have 2by...

Completely agree. I'm a long time user of Sram 1x and 2x products and have had good experiences and will continue to use it but I think this push to road for 1x is a losing battle for them. Whatever the underlying issue is, they just can't clear it reliably, even with this new Axs update in road applications. You could chalk up the Aqua Blue thing to essentially finge/beta testing. The Axs rollout was their chance to show the reliability was sorted and get back to pushing the potential benefits and they whiffed.

[Mark McM]

Originally Posted by oldpotatoe

Guess we’ll have to see what Trek has on their bikes this Sunday and then next Wednesday. I’m betting they have 2by...

Or they install chain guides:





If 1x is as immune to chain dropping on MTBs as claimed, why are they so many models of 1x chain guides available for MTBs? Heck, even the makers narrow-wide chainrings (that are supposed to prevent dropped chains) make chain guides.

[batman1425]

Originally Posted by Mark McM

If 1x is as immune to chain dropping on MTBs as claimed, why are they so many models of 1x chain guides available for MTBs? Heck, even the makers narrow-wide chainrings (that are supposed to prevent dropped chains) make chain guides.

MTB (particularly trail, enduro, and DH) has some unique needs. A MTB see impacts and chain movement that necessitate further retention insurance beyond a narrow wide ring and clutch that are potentially overkill in other scenarios. Is it perfect? No, but condemning the system because it can't keep a chain on a bike through a rock garden or big drops 100% of the time is overly critical IMO for that application. A chain guide is still lighter than a FD if needed.

Lots of XC riders go without chainguides on 1x setups without fuss. How many pro cross bike run 1x without guides? It can be and is effective in other disciplines without them. Should road have guides? I think the data suggests yes but I also think the dropped chains are for different reasons that are typical in other applications.

[JStonebarger]

Originally Posted by benb

Is there an aero advantage?

A lot of time trialists go 1x for an aero advantage. My understanding is that most bikes will save around three watts without a FD. My frame is reported to save twice that.

I just switched, but on a TT bike it's pretty easy to stick close to an optimized chain line...