island rider

For some reason on my trainer (Kurt Road Machine, stock) it seems harder to maintain speeds that I normally easily maintain on the road. Setting aside issues of possible downhill grades and tailwinds (neither of which I believe actually exist), is there some reason for this?

Do you find that your speed is lower on your trainer that is would be on the road with the same level of exertion?

(Of course, I am also willing to accept that my engine functions better outside, or that the nut on top of the saddle is the thing that needs adjusting.)

skol

all you have to do is stop pedaling on the trainer and see how long you can coast to see you have forces working against you that you don't have on the road (assuming your not hill climbing or riding into a 30 mhp headwind)

island rider

I'll buy that. Thanks.

Velo Dog

I've been whining about this for years, and I've heard all kinds of reasons advanced to explain it. Leading theories seem to be that you can't coast on a trainer, while you often do coast, if just for a few strokes, on a real ride, and that riding the trainer is so boring it just SEEMS harder. But you're right--even when I'm in pretty good shape, able to do, say, hilly three-hour road rides comfortably, 45 minutes on the trainer is an eternity. I'd rather ride outdoors in 20-degree weather.

jwible

Speed and distance on a trainer are not analogous to what you would do on the road at the same level of work. Trainers are evil in that regard. I don't worry about speed / distance but focus on time / power / hr on the trainer.

Ygduf

I know that even if I focus on just HR, my spin bike feels more strenuous than an outdoor ride. I can comfortably work in the 160HR range on the road for a 2-hour climb; on the spin bike 160s HR just feels harder. Maybe it's the lack of air/increase in sweat pouring off me, or that it is ZERO fun, but it definitely feels harder, even at the same heart rate.

wanders

I may be wrong here, but I think I remember reading that the KK's trainer speed was the equivalent of a 1% grade road. I am off now to see if I can find it.

wanders

Not sure if I'm reading it correctly but here's the link.

https://www.kurtkinetic.com/powercurve.php

"With Tom’s help, we have been able to create an “average” rider assumed to be 165 lbs, riding a 23 lb bike with 170mm crank arms up a 1% grade, at sea level with no wind on rough asphalt... etc."

jrobe

This is normal and won't change. In the last 2 days, I rode my trainer one day and Cross-Country skiied the next day. My average HR was 10 beats higher on the ski day but I swore I worked much harder on the trainer. There are enough distractions exercising outside that my perceived exertion was significantly lower on the skiis.

Pedaleur

Speed is utterly irrelevant on a trainer. There's no reason that the mechanism, whether fluid or magnetic, should match all the forces on the road. I turn a much bigger gear, for example, on my trainer than i would outside at the same power.

Now, your power may be lower for a given exertion just because of environmental effects (overheating, for example). There was a thread on that not too long ago.

bdcheung

PE on a trainer is higher because...

1) Mentally, the scenery isn't changing. You're not moving. In fact, your entire existence is focused on how much the trainer sucks.
2) Physically, there is not the same volume of air moving across you to cool you down as there is on the road. So you're hotter. So you're more uncomfortable. A minute in hell is a lifetime.
3) Inertia is lower, so you are actually having to do more work overall. This ties in to the "coast down" effect.
4) You never stop pedaling. All those little breaks on a ride - going downhill, stopping at an intersection, etc, add up.

IMHO

island rider

"The Kinetic Road Machine power formula is accurate for all riders because the variables experience on an outdoor ride are controlled indoors. We are so confident in the accuracy of the Kinetic Trainer; we encourage you to try this test. Complete a 20 minute time trial on the trainer using a rear mount bike computer or Kinetic PC (Power Computer) Complete a similar ride on a flat course with a neutral wind. The distance covered will be within a range of + /- 3%."

Ok, let me try that. First I have to build a flat road more than a mile long. Second I have to put a tunnel over it.

I think I'll just accept that I am not, nor will I ever be, 165lbs and that I can try to maintain my road pace on the trainer (no power tap, no HR monitor) and it will only benefit me in the long run.

baribari

Isn't it simpler to just assume that the trainer's resistance is greater than the air and rolling resistance you experience on flat, smooth roads? Perhaps it's equivalent to a slight upwards slope.

Also, when you're on a trainer you only have the flywheel and the drive train + rear wheel to provide inertia for coasting... on the road you have you're whole weight added to the mix.

island rider

I think this is really it. Looking at cadence and gearing I should be registering higher mph. The mental effects are completely true though. The never stop pedaling point contributes to the overal PE, but not the moment by moment speed difference.

Thanks guys. Wanted to make sure I wasn't just nuts.

Grumpy McTrumpy

more work overall?

my power meter data disputes this.

watts are watts

joules are joules

I do agree on the boring aspect and on the cooling factor.

merlinextraligh

This pretty much sums it up.


Of course the resistence isn't the same, which is why speed on the trainer is irrelevent. However, it doesn't explain why the PE is higher for a given wattage output.

Voodoo76

This is the key. If you are soaked in sweat on the trainer then you know there is not enough evaporative cooling going on. A small increase in core temp can make a big difference. Wear leg warmers on an 80 degree day and see if you dont get the same feeling.

RazorWind

This right here. An hour on my trainer seems a whole freakin' lot harder than an hour of actual road riding because it really is harder.

island rider

You guys and your fancy power meters and heart rate monitors. All I have is my computer with cadence and speed...

Urthwhyte

Much as others have mentioned, using the trainer is very similar to running on a treadmill, the runner's equivalent of hell on Earth. There's less air moving around you, meaning that you heat up much quicker, there's no way to coast and so you're constantly pedaling, the trainer doesn't promote movement nearly as much as being on the road does such as getting out of the saddle to go over a pothole and mitigate its effects; all combine to create a far more miserable experience than on the road, which doesn't help with the perceived exertion level at all.

RacerOne

Agreed on this PE does seem much higher, but on the other hand, I am more disciplined when on the rollers to complete a specific workout at a specific heart rate, etc. I figure if I'm just sitting there I might as well do it right.

a_thomasmr23

Well you use about 3/4 of power produced just cooling yourself so if there is no airflow your body has to work much hard to cool. And since that level is limited due to lack air so the body puts a cap on the power that its willing to make. That is the bulk of the difference. Bicycling Science goes into this in detail.

Beaker

You can get a great workout on a KK road machine. I use the speed to help me monitor power output, but not to correlate to road speed. The power correlation is useful for doing intervals, for those of us lacking Ptaps.

nitropowered

You coast about 20% of the time when you are riding on the road. I would not say you don't coast at all on the trainer, but I'd estimate <5% (changing positions, slight coast to stretch, etc. )

You are also fixed in one position. On the road you can move the bike around and use what little upper body we have to help propel the bike. I find it nearly impossible to replicate my sprint power on the trainer.

You run hotter. No matter how fast I turn on the fan, I still sweat buckets. On top of that, my feet and legs get cold but my upper body is still red hot.

aham23

you guys coast when on a trainer. interesting. later.