There's a lot going on here to pull apart and analyze. First up: That Tacx NEO 2 is known for virtual flywheel slippage (same as the Neo 1. Issue addressed with the 2T). That could be robbing you of watts in either measurement and/or with providing inconsistent resistance with the shorter/harder efforts. Retest on a Kickr/Core/something with a heavy flywheel. Roker Plates: I've presented my experience on these across a number of videos. In short, I wouldn't recommend them to anyone if they want to work on their sprint technique. People will say "But if you learn...."... yep, stop there. An experienced cyclist having to 'learn' anything means it's different. If it's different then by definition it's not the same as outside. Rocker plates have their place. That place isn't sprinting. I'd love to see more people like yourself get a rocker of some sort and cover the experience. A lot of the comments and reviews are from sponsored riders or people with a commercial interest in the products. Beware. They're a protective bunch..... Technique: Outside there are SO many factors involved in a sprint that will never be replicated inside. Sprinting is a skill that is so much more than just pressing on the pedals hard. To succeed in a 'virtual sprint' that's all you need to do. Press the pedals hard. The dial sided 4iiii: Some people have referenced my data/report on those. It's not as easy as writing them off as 3% lower on the right. Anyhow, get yourself a rocker plate, retest.... let's see how it pans out. It's an interesting topic.

I guess being strong on the indoor trainers use more legs and out doors use whole bodywork. Thanks for sharing. Love the video's.

Counterpoint: I've found that practicing sprinting on the trainer (which really focuses you on how power is transferred through the pedals) gave me a sizeable boost in my max outdoor wattage.

From personal experience, I find it's more about timing that peak power, especially as many have also noted that everyone else on Zwift is also losing about 10% of their performance. In real life you're sprinting for a specific line, so you know how hard you can go for how long and you (usually) time a sprint against that. On Zwift there's always a lag, either from your flywheel spinning up or the actual lag between your ANT+ signal and that signal registering on Zwift itself. As such, I've found it's better to go a bit earlier than you normally would and run out of juice about 50m before the line. Zwift will still carry you across that line at the same speed. Of course, there can always be another rider who goes over the top and pips you at the post but that happens in the real world too!

god bless you for doing 2 FTP tests i can’t bring myself to think about them

I cannot fully convey how grateful I am for your posting on this specific topic. I've been so demoralized seeing 10-20% less power on all durations below ~3-5 minutes when Zwift racing (I use dual pedal based power - so same unit inside and out). I am so glad to know it's not just me. I swear I thought I was just doing something wrong. I have pretty similar sprint numbers as you (but slightly lower, and I'm heavier). If you're looking for more confirmation from anecdotal sources, look no further! You can add me to the pile of new Zwifters (due to the COVID19 pandemic) who can't sprint worth a darn on an indoor trainer.

Loving your great work and thoughtful approach! In addition to the question of sprinting technique in- vs. outdoors, i was wondering about other bike induced factors, that impact sprinting. With regards to future riding outdoors and the @trainerroad deep dive video sample on nate vs. pete sprinting: i would like hearing your (or maybe collaborative) take on body proportion and technique related to bike geometry (crank length, handlebar shape, etc.) and standing weight distribution and stability regarding max power and or speed. Greetings from germany

Hey Jeff great video. I would really love to see you make a video on sprint technique and form. I feel a lot of people including myself have trouble when the cadence is high while sprinting out of the saddle which is important as that higher cadence is necessary for high power and that snap, I think. I really enjoy your videos, they are both entertaining and enlightening. Keep up the good work

great video, yes you nailed the difference between indoor & outdoor sprinting. core muscle activation, upper body strength and L & R inertia all play an important part in maximum force generation. also on trainers there is almost no recovery component (i.e how much of your total % is below say 140watts) less than 5% of total ride time. What does this have to with your final sprint i hear people say? well turbo sessions are much harder as there is no micro recovery phase before the final sprint.

A little late to this video, but wanted to point out that I'm a 2000W sprinter and previous owner of a TacX Neo2T... The issue I found with indoor training was the slippage...the magnet system as opposed to belt can't keep up with the burst of power and it just slipped

Hi @NorCal. I have a hypothesis on this that differs from yours in that, while I agree that technique have a big impact, it seems to me the trainer motor is the dominant culprit. It goes like this: While I think they way the motor ramps up to provide x-watts of resistance diminishes performance. I think this part is traininable to some degree. Similar to learning to sprint on a static trainer, methinks. The real watt-thief, IMHO, is the "nature" of watt-bike resistance. Take regular human-watts delivered outside measured with a strain-gauge type power meter. We non-motorized bipeds sprint to say, 1000 watts for my example. The _way_ we do so is what I want to draw attention to...we achieve this 1000 watts in "pulses", right...with each piston-like stroke of our legs. We are really averaging 1000 watts over the course of time vs. 1000 watts divided by 360 degrees of a crank rotation. We have dead spots...say 45 degrees for each leg, or thereabouts. But a watt-bike delivers resistance in equal 360 degree bits/quanta, right? That dead/weak 45 degrees (or so) for each leg is what we really are not used to/expected to sustain. That "constant braking" of 1000 watts is really felt against our dead spots and makes achieving compu-trainer 1000 watts either mentally or physically harder (or both). This is why I feel sprinting to outdoor peak is harder on a smart-trainer. With all the usual caveats of outdoor temperature, distractions, technique, et. al. (This is also why I think smart-trainer high-watt intervals are harder than outdoor :) )

I love these vids you guys crank out. I would add though, for someone like myself, who (at least in the summer and fall) has a decent FTP for a lay person (320 watts) and really poor top end power the trainer has helped. Perhaps its simply because I can still ride in inclement weather but I have added some sprint effort workouts to help this area of my riding. Much of those are done inside on the trainer. I've seen an increase inside and outside as it relates to my sprint power. My peak 1 second numbers have come up a bit, my 5 and 10 second numbers a fair amount and they're far more repeatable now vs 9 months ago when I started doing sprint intervals. In fact I've had repeated intervals at > 1000 watts, which I realize isn't a big number, but for me that was always a stretch, I might hit that once a week if I really tried. A few days ago I broke 1000 watts four times in a row. I can only attribute this to training and working on my sprints. So while an indoor trainer isn't perfect I'd say it's still helpful, at least for those of us that aren't at the pro level.

Completely agree! So frustrating. I’ve peaked at just over 1800 watts outside on two occasions, but I’ve never seen over 1550 watts indoors (cyclops magnus and new Kickr). I’ve given up sprinting on the trainer. I’m sure it’s putting a ton of stress on both the bike and the trainer as well.

I wouldn’t recommend one of those wheel on rocker trainers. At those wattages, your bound to get some slip on the wheel unless you really crank the tightness of that roller on your wheel. I’d look at the rocket plates that you place your whole bike on including trainer.

I had a Rock n Roll and the wheel slippage can be awful even at medium power. Switched to a Neo. But I believe Kinetic is coming out with a direct drive version too.

You've done it again! I always felt like a weenie sprinting on my trainer in ZWIFT and wondered why I sux. So, partly because I have to ramp up first before ZWIFT acknowledges that I am putting out more power but also because I can't 'rock" the bike and pull (with my arms + core) and push (with my legs) at the same time. Where do I send the check? LoL Good job!

I've been running a KK Rock n Roll for 10 years. Definitely more comfortable. While the rock n roll motion is not hugely advantageous in terms of using your full body to rock the bike on a sprint, it definitely allows the basic side to side movement needed so that you can stay straighter without bobbing up and down as much. I've tried sprint on our static Tacx and it was brutal in comparison. I just ordered an R1. The thought of a fully static trainer gives me nightmares.

Please do a video on sprinting technique and how to practice good form. I have a terrible sprint at the moment, but with training and focus I can develop it to be somewhat competitive as a lower-category rider. You make excellent videos and I think something like that would be well received.

Awesome video!! Gives me some hope!! All my power numbers that I go by are from Zwift. I need to buy a power meter ASAP!

Insightful comparison between sprinting outside & indoors When riding off the saddle outdoors, as you stated, the bike shifts & you're able to use your body when you sprint. Indoors, the bike is fixed so shift your body weight & lean down on the stroke to power up instead. Appreciate you putting your racing IQ & perspective out there

Nice to see you riding in my clubs event (Glasgow green) from across the Atlantic! I won my first B race the other week so I guess I might need to try and chase you in the A races some time soon! 😫😄

NorCal, thanks for another interesting video! Could you do one on picking the proper gear to start your sprint in? Sometimes I get a little greedy and go strait for the 53x11 and my acceleration suffers cause the gear is too big for my current speed. Do you just go on feel? Is Cat 1 racing fast enough 53x11 is just always the place to be for the sprint? Maybe the wind is strong enough the leadout is slower than normal? Maybe an uphill sprint scenario... Do you ever grab another gear after starting the sprint in the 12/13? Would love to hear your input on this... wouldn't even complain if you used the word Frenemy haha!

Thank you for the video! Do you wear your prescription glasses when on the road? If not what do you wear?

I wish I had seen this video earlier. As some have noted, the challenge for indoor bikes is simulating inertial resistance - particularly when trying to replicate the behavior of larger gears used in sprints. The problem: tall gears resist acceleration but allow relatively easy pedalling at constant speed (when you are not dealing with significant wind or rolling resistance). With a road bike, you battle strong resistance as you accelerate but can use almost no effort at a steady pace. A Tacx trainer was used in this video to simulate road bike acceleration behaviour. They didn't quite get it right. Their software resistance model (a.k.a. performance curve simulator) is the culprit. Most indoor bikes resist too little during acceleration and then offer too much resistance during steady state riding. Remember, simulated gearing matters! If you are modelling a low gear, resistance to acceleration must be low. With a tall gear, resistance to acceleration must be almost exponential. Heavy flywheels simulate resistance to acceleration but can be too forgiving with steady state riding. The best answer: A hybrid with heavy flywheel, proper freewheel and integrated software to create real world resistance curves. The best choice today is probably the Waho Kickr Bike (www.wahoofitness.com/devices/smart-bike/kickr-bike). It has gears that are fully simulated in software. It can replicate resistance curves better than a bike trainer that has its gears set physically outside of the software.

Same thing here! My peak is was about 300 off too.. I think the reading is more off if more left to right motion is involved.

Sprinting out of the saddle does two things - directs the downstroke slightly outwards and lets you balance by moving the bars opposite (just like a running sprinter, or skating sprinter) - make the crank arm effectively shorter To compensate for both on the indoor trainer i think you can try - think of pushing directly up / into the bars for balance since you can't move side-to-side / up-down - start your sprint in an easier gear than usual

I use the Kinetic rock n roll control, I find that without rocking my knees ache after an hour, and even a little movement of the saddle helps reduce chafing and soreness by spreading the pressure around naturally. I think there's validity in the a loss of peak power due to inability to efficiently engage your entire body if you're completely acclimated to IRL riding, but in Zwift I'd wager the results have more to do with tactical application of power first, and raw wattage second. Throw in power meter discrepancies, data drops, body mass sandbaggers, data dopers, etc, personally I don't bother with racing and stick to guided training.

already commented before but watched again, my zwift sprints arent much different. but i also race on the track and do a ton of seated big gear accelerations. gotta be that i just dont rock the bike much outside, but i also dont need to. i can hold myself in place solidly and crank out all the watts without wasting energy

I have the kinetic rock and roll. Yes, it simulates more of an outdoor feel in that you can use your weight to raise wattage, but the tension isn’t controllable and the integrated power meter is very questionable, best to use a normal power meter if you have one. Plus, the wheel slips somewhat, especially when you’re sprinting.

I love this analysis. But, wouldn't these numbers also apply to your 'virtual' competition?

I have a rocker plate for both wheels with my Wahoo kikr Core, it is great but still not like outside. It's a bit awkward on the sprint but great on the climb.

Been on zwift for some years now Racing/training and Casualy outside. this year 2020 I planed on trying some shorter licens racing. I am a sprinter as well .. And on the Road I can hit 1300ish in zwift I max out at around 1070-1100 MAx .. Personaly I think its the Arms pulling the bike to the side must add the last 200+ watts that go away I know I was kinda suprised about the amount of force I had to use in my arms.. 2nd Would love some advice or info about how you find the right gear/candance to sprint in ? or spend a min in a vid to talk about it =) anyway keep up the good work ..

I use the Kinetic rock and roll smart trainer for a few years now. I can tell you it's still a bit different but it's way better than other trainers that locked you in in the same position.

When you did the indoor tests, did the wattage from your 4iiii power meter match what your Neo was reporting?

i can get that to a certain extent with it being different , however like time trailing position compared to road , the difference in watts could be reduced if you spent more time sprinting on the turbo .

Il have the same issue with my sprint , is 300 watts less than outside. Inhave test the neo 2t and the saris h3 , and its the same résult. I usually ride an inside ride , and even with the « e-motion » its impossible to reach number i frequently touch outside. Accordons my experience Its impossible inside to use the upper body the same way we use it outside. At least its make you mentally hungry when you go outside . And great work with all your video!!!

Fully agree and have experienced the same. I can do 100-150 watts higher in sprints, and several watts higher for the 2-4 min efforts outside. And I weigh 126 lbs, so that is a big difference for me. I also have a Neo.

ill tell this to you straight. I thought the same thing with the Kurt kinetic rock n roll trainers but the problem is that the recoil springs are so hard that you can't exactly pull your bike up because the recoil springs do it for you, it messes up form and position badly, like its a very very unnatural feeling (i am a sprinter). it's like the feeling when you are about to fall but your wheel suddenly gains traction and pushes you back up. 10/10 would not recommend rocking trainers. Something I hear great things about however is those platform rockers that use minimal springs which have a total rocking freedom front to back and side to side in a radial motion, they are very smooth and simulate the real world. one thing to keep in mind with rockers is that as sprinters, we rely on the moment of inertia of our bodies to stay in position when accelerating. this increases the normal force we push on the pedals, it's the same reason why you have higher power retention while climbing.

5:32 super-domestique

Hi, two questions: 1) did your Neo survive after sprints? My Neo1 was wrecked after a few springing sessions - bearings just died and were super loose and whole trainer super noisy. And I'm considering myself as a very poor sprinter.... Eventually I sent it out as Garmin didn't want to fix it (!!) 2) Did you compare power readings from 4iii and Neo? I've noticed 6% difference between my Assioma Duos and Neo1. Did a static test on the pedals, they seemed to be well calibrated. Still chasing a new Neo (this time 2T) to see if there still will be a discrepancy.

This video is true but... zwift is the same for everyone Everyone loses those 200-300 watts

I used that exact rocking one, the Kinetic green thing at a shop down in Florida. It's a touch disconcerting, I felt like I might fall over at times.

Great video I appreciate this as I’ve been wondering about this for a long time! Just a question, is there a reason you’re not riding your venge on the trainer?

I have a direto, use 2cm thick wood in the middle so I won't lose power there, use pieces of foam on the outside so I can rock just enough to make it feel natural. My first intention was to reduce strain on my frame but it feels so much better as well.

Love racing with you, I was impressed to come 3rd behind you, because I know your sprints and I’m 15 with a 850w sprint😂, you’ve also got to learn the game. When I saw your name after the race I immediately checked to see if you were steaming but at least I got in this video😂

I have the Kinetic Rock&Roll and I do agree that it is easier to pull and rock the bike to generate power. I am not a great sprinter, but I like the more realistic feel when I am out of the saddle. I have a similar problem with sprint power on the trainer vs outside but I have a different theory. I am not saying I disagree, perhaps a combination of several factors create such a large variation at high wattage. I am not a physicist and do not claim to have done any science or testing to back this up. But... My thought is that it is more to do with torque and the amount of resistance provided on the trainer. You can only push so hard and then you need to start pedaling faster. I run out of gears, I think if i had another two gears I could generate more watts. I can just push harder on the bike outside, without having to increase my cadence. There is just more resistance, to me anyways.

As a former track sprinter I literally used to power my bike about a foot from side to side with every pedal stroke. I can't do that on my Neo. :-(

Any idea if the sprint power is influenced by the way the controllable trainers adapt to extreme torque? I hit 1500ish on the road for 5 sec max but only about 1250 on a Tacx Neo bike. It always feels like I cannot generate the same leg speed as quickly on the trainer. I don’t think it’s related to rocking the bike.

What is your gear combination on that sprint 0:01?

How did you account for wind resistance between inside and outside?

Cool vid? Curious - I notice you drop your heel at around 3 o clock. Is this a conscious effort or is it due to bike fit/position? I’ve read some things saying that dropping the heel results in more power output?

I was wandering the exact same thing. Thank you for the explanations and well made video.

Wondering what your cadences were at max 5 second and 1 minute output on the trainer and outdoors? Outdoors you're pushing against significant wind resistance at sprinting speeds that gives you higher watts for the same cadence and cassette cog as you would get on the indoor trainer.

I LOVE your intellectual approach to everything. You've got a fan in NY. Great job. Zwift has gotten me in really great shape and I knocked another 2 minutes off of my 10 mile stretch near my place in upstate NY. I cut a total of 4 minutes since March. Zwift is good for just that. I don't take Zwift results too seriously.

I think a big variable that is different indoors and out, especially for the 5S power, is inertia. I think you'll have to pick up alot more cadence over the 5s indoors because the inertia is lower.

There’s also a ‘flat peak’ (vulcano shaped) in your power graph. Isn’t that like tacx in filling in formula-wise what the power will be? What is the power meter/zwift doing when there’s the flat area? Another thing, you said others where passing you in zwift during sprint. That would mean they don’t have the same problem (or better trainers/powermeters)? I am curious what you’ll find, as i face the same problem .

The problem I have with indoor sprints and its probably my bad form but I manage to move the entire trainer forward with me which knocks the front wheel of the base and makes me loose balance. I managed to get a better hang of it last season but when I returned after a season of outdoor, the problem returned

With my wahoo kickr I am able to put out almost the exact same power in sprints as I can outside. Does it have something to do with the weight and stability of the trainer as well? I noticed your trainer was moving and my wahoo is solid.

My first thought was correct I see that when you are able to lean the bike your leg has a slightly longer fulcrum to add more torque to the system generating more watts

I’m sure this has already been mentioned but you could buy a rocker plate to put under the turbo. Essentially two boards with damping in the middle allowing some lateral and front to back movement. Fairly simple. You could make one at home with some ply boards and something like a tennis ball for the cushioning. There’s probably a how to demo of how to make one somewhere. As for the sprinting, I don’t Zwift but have been watching a lot lately (no real races to watch) it seems that you have to go for a longer sprint than you would in real life. There may be some lag in the software were it takes longer for the power to spool up, then stays higher for longer. The whole aero advantage thing seems to be bizarre too, not the same as real racing. If you are doing a max effort in real life it’s very difficult for riders to pass you. In Zwift it seems easy to jump on the draft and pass 10 riders in front of you, where in real life there is no way you’re going to find a gap to get around them.

Maybe part of the problem is that you are putting energy into flexing your frame back and forth on the trainer as well, since it can't freely move around under you. I would expect that a flexy trainer mount might help, but even that is going to pump some significant energy just into bending that spring back and forth. Really, what would be closest to riding outdoors would be a set of rollers, with a resistance unit built into the rear wheel. (If you try to put >1000W of resistance on the rollers, your wheel will climb right off them) Contrary to what a lot of people think, just because the spring returns, It's not preventing the energy from being wasted, since it's giving it back at a time that it's not needed. In the same way, If you tie 10lb weights to your feet, any energy that you put into lifting them is returned to you when you put them back down. But I would bet that you're not going to be able to run as fast.

Are those rocking trainers closed loop like Kickr, Trax, etc? Assuming one can afford a closed loop trainer, that is the only way to go. Great channel btw.

I wonder if Chris Pritchard has the same loss on the indoor trainer. He hits some monster watts on the Wahoo Kickr but not sure how that compares to his outdoor sprints. I always thought he should do a video on tips for indoor sprinting as I would love to find my missing 200-300 watts.

I don't have a power meter for the outdoors (yet) but this video makes me feel super nice, since on zwift I've hit 1234 for 5 seconds, so I'm really curious what I can do outdoors.

Really interesting comparison! I still have a very cheap Turbo Trainer and Zwift Sprints are even more awful because it stops at 400 W..

I believe dc rainmaker did a video also on the issues of maximal power loss through indoor trainers, basically it's the delay in the trainer picking up the power applied from the rider, it's something that most if not all indoor trainers suffer from.

Nice man! We almost got the exact same power numbers ( outside and Zwift)! I never raced but this gives me some confidence :D

Great video ! Have you changed your technique or found anything that helped after this video aired ?

Problem is two things no side to side movement which adds to momentum and the fact that you don't have forward momentum (velocity) in doors your bike is static and you can feel that in your legs when you sprint, in doors you can't wind it up in same way as outside, as in doors you have constant pressure or load on your legs because of being static. I would think you would feel slipping as I have a Neo 2T I have had it happen on a climb once when I put in some high watts from slow cadence but that was all.

That's always been the limitation of static trainers that hold the bike stationary. Rollers and treadmills wouldn't have the same restriction (in theory). However, based on what's available, there doesn't seem to be much demand for these - something I've never been able to understand.

If I could subscribe twice just for the pain and suffering, believe me, I would. Very interesting to see the comparative numbers - I'm sure the folks at Zwift get a lot of this, but I forwarded the link to them anyway! _"Take that! You, you... software engineers, you!"_

That Kurt rocker is the trainer I have. I am a bigger rider and I get tire slippage when I try to throw a big sprint. It hits 800 watts with the slip. The side to side is nice, but for me it can bounce up and down slightly might be my weight. It got used to it but I still feel it at high cadence.

You should try putting the trainer on a thick yoga-mat, or even two. I have my kickr core on one thick mat, and this gives me much more movement in sprints.

Can you make a video on sprint form!! I know trainerroad did a video, but more takes on this would be helpful

I noticed how much your bike wobbles on the trainer, which is a thing with all trainers. This is the reason I bough spinning bikes, you don't have to shell out a lot of money if you sit on craigslist for a few weeks or go to an auction on a good selection day. With that said, I'm wondering if you would plop those 4iiii power meters onto a spinning bike (pretty much all of them is very stable, I had Sunny SFB910 from craigslist, was very stable, so even the cheap ones) could you get rid of the unconscious carefuleness and really pound it? Could you generate more power on those?

Thank you. did the rider who beat you use the same trainer or was it the rocking version?

Hello Pro Rider I usually give you hard time. But you resolve my issues I was wonder the same thing I have the same trainer but I couldn’t do the same power from out sprints ftp to inside Sprints ftp. By the way the the bell 🔔 save you’re this pass weekend on Clarendon hope next year seeing you there.

Two FTP tests lol this man deserves your like

This is a great concise and clear video. Love it keep it up.

Theres a few reasons this could be happening. The best comparison test u can do is record on ur gps head unit and record on zwift and compare the results if theyre the same most of the reasons are moot. Zwift may smooth out your power input vs the action on the bike otherwise u could have ur virtual rider standing up to sprint for like a half second at a time because it misread power inputs. Theres a delay between the effort u do and the time ur power meter sends it to the ant+ dongle and the time zwift takes to get the input, process it, and then output the result in the game ive personally found that the ant+ dongle doesnt work that great unless its right next to ur sensor like taped to ur bottom bracket next to ur power meter. It could be the fact that ure just not as motivated to output more power like u are outside because theres no risk of falling over or trying to outrun a car or another cyclist. It could be that it has to do with muscle memory associated with the amount of air flow. I notice i can coast way further a n longer in real life than i can in zwift so its def robbing me of aerodynamics or rolling resistance soem where

Tell me about it. At least they changed the weight cap so as a junior I can be 40kg

I have my masters degree in epidemiology/biostatistics and I love your study protocols. This setup eliminates a lot of biases that can happen. But for a true conclusion, percents are superficial. Run these datasets through a t-test & nonparametic testing. This will tell you if your differences are meaningful or not & can help generate a p-value. Although a larger sample size would be better.

I admire your analytic approach. But this one is easys to explain. Of course it‘s the wiggling from side to side. You as a sprinter can decrease the inertial resistance by doing so. By pulling on the handlebar you then transfer your power and bodyweight into the pedal. Bad sprinters just wiggle and don‘t have the proper timing of the armpull. You can‘t do that on a fixed indoor trainer. But if you manage to increase your watts on the indoor, your outdoor sprint will get even faster.

Jeff I know this is an old video but just wondering if you ever tried a rocker plate after doing this one and if so how you would compare it to outside against a regular stationary non morning trainer.

How did you get the power and heart rate overlay?

8 months ago I clipped out while sprinting and crashed bigly. Now I’m afraid to sprint and haven’t even tried a single time over the last 8 months. I even descend hills slowly because I am so afraid of crashing.

The comcept that rocking improves power is a good subject for a secondary test. what if you tested outside sprinting sitting with high cadence and then duplicated that technique indoors on a locked trainer. When I sprint outdoors I use both techniques. A jump sprint is usually drop some gears and stand, opponents can hear the shift and can react quickly, sometimes I just spin up my cadence first to around 150rpms.

I think the problem with some of the rocking trainers is that they rock the opposite direction as you would normally rock your bike out of the saddle on the road. Also, get used to seated sprints...

Very good investigation, I think. Since the training unit is central to the whole scenario I would think that a comparison should be made with another trainer, say a Wahoo Kickr. That should give an idea as to whether the Neo2 is the culprit here - or not.

I tried Tacx Neo Bike, which is very rigid and Wahoo Kickr Bike, which has a lot of flex. Both for at least a couple weeks. To me it was fairly normal to push close to 1200w on Neo Bike (15w/kg), but I can push about 10% less power on Wahoo Bike. So in my experience rigid allows for more power. Have no idea if flex feels more natural, I am a complete amateur, almost never biked outdoors and only started seriously biking on trainers in Zwift in September, but it does feel like flex takes away some power on a trainer.

I use a kinetic rock n roll. To be honest the range of motion is not great enough for all out flat sprints. Its great for being out of the saddle on climbs because you rock the bike less violently and the trainer moves more naturally.

Haha crazy you’re doing a Glasgow Green ride, my local route here in Glasgow!🤣👑

i love my Kinetic Rock and Roll Smart Control... though I have never tried one that doesnt rock so I cant really say much for any other.

I wonder if there was a way to measure how many watts you are generating through your arms and moving the bike back and forth. It would be cool to see it while standing on a climb and a sprint.

With the conclusions you have from these tests have you thought about trying in the saddle sprinting for zwift races? Maybe the reduced rocking from being in the saddle would create more parity between inside and outside performance. Also, it might just be interesting to play around with since there's nothing else to do right now :D

You got me into cycling due to covid. But I can't get over 20 mph. I can hammer 530-6 minute miles running and biking is easier on my joints but I can't come close to 30

Yeah, indoor vs. outdoors sprint are very different whole body movements. However, my indoor is just as good as my outdoor. My thoughts on this was always that I should be able to create more power indoor., since less balance and awareness is required you can therefore go little more rage-mode. EG - no need to have eyes open looking at the road. Just ballz to wall thrashing on the pedals. All that being said, I have more success winning B races on Zwift with loooong sustained sprints well under peak rather than explosive sprints which seem to work better outside.. so I think its the trainer + the game making the difference

Would a single sided power meter have a different power reading to a dual sided one? I use the elite direto as my trainer which I can put out close to 1300 watts on but outside with a single sided stages crank i find it hard to put out over 1000. Would it be higher with dual sided?

Another thing is that your front wheel isn’t spinning at all on the trainer, so there is no angular momentum holding the bike steady to push against when you sprint. It’s probably not as big of a deal as not being able to move the bike with your arms, but it looks like it matters a bit.

It could also depend on the type of smartrainer, ive seen reviews on the Kickr which shows peak power could be more than 100w higher compared to other PMs