A turbo trainer that measures power?

fat bloke

Been using a powertap for over a year now, and sharing it with my significant other. This can make what can be a fraught relationship even fraughtier (frothier?) . Swopping the powertap wheel from bike to bike and swopping / setting respective bikes up on the turbo is becoming a pain so we could do with an easier solution. It's hard enough to box off an hour to yourself besides wasting time mechanicking.

Anyway, I caught her googling such things and figured some more research was needed. It seems to me that there are perfectly good turbo's for a couple of hundred quid, and then there are ridiculously expensive power measure ones for 2 grand, and then in the middle are multi-function things with all sorts of bells and whistles and which also claim to "measure" "power". There's a qubo one and a tacx one I think, and they're around like the 500 quid mark.

My gut tells me that they're a load o' boll0x , but does anyone here actually have one that could give us a heads up?

Myself and the mrs run the turbo ragged between us so this is something that will be used a lot and so it's worth or while getting something decent, and we are training with power and power metrics so we want something that will accomodate that. Basically I suppose what I'm saying is I don't want to start a powermeter haters v's the world thread, or be recommended the best lights for night training, or vouchers for a spinning class. :rolleyes::o

couerdelion

Have you looked at Trainer Road?

I use it last year with a Cyclops Magneto and the power figures seem pretty much in line with the Power2Max I bought recently. Just need USB dongle and ANT+ Speed /cadence and then sign up for $10 per month or $99 per year.


I know some people say that the power is way out for their turbo but at least it's consistent. There's also plenty of plans and sessions to chose from to make things more structured / interesting.

detones

I have a tacx flow which I picked up second hand. Think there 300+ new. It gives you some rudimentary power data. The general concensus is the values are not that accurate but they are precise on repitition. So you get a consistent value to compare to but it may not be near your real wattage. It's still useful and its something to distract you enduring the torture which is a turbo session. This winter I just bought lights for the bike ;-)

fat bloke

Yeah something consistent is fine once you get dialed into it.

Can you clarify something else for me. Some of those flow / fluid turbos with this automatic resistance changing thing -how does that work cos it sounds like something I don't want.

My intervals tend to be lets say 10 minutes right, & every minute I need to change cadence but maintain my power, so I have to up the resistance for lower cadences to keep my power metric up, so I really need to be able to control the resistance manually and precisely (some fine tuning comes from changing gearing too).

How does that work then work then with the fluid resistance trainers ?

detones

The tacx flow is electronic unit with a digital disply control. You just push a button to increase resistance. The flow shows this a %incline like climbing a hill. The display shows show speed, power and cadence. You can get an add on to connect all this to a pc and use the virtual reality interface.

AmberGold

I have the TacxFlow also. While I haven't had a chance to compare with my Powertap it feels close enough.

fat bloke

detones wrote: »

The tacx flow is electronic unit with a digital disply control. You just push a button to increase resistance. The flow shows this a %incline like climbing a hill. The display shows show speed, power and cadence. You can get an add on to connect all this to a pc and use the virtual reality interface.

THanks. -I've no interest in the VR thing, too much netflix to be catching up on

Is it all ant+ compatible to hook up with a garmin or are you stuck with the tacx digital display thingy?

doozerie

My experiences of using TrainerRoad with a Tacx Flow are here. I've found it very good overall, and not just for its power display. One proviso though, in order for the TrainerRoad software to calculate your "virtual" power you need to set the Tacx Flow to a particular resistance level (+2 for the device profile that I use as per the post linked above), so if you change the resistance mid-session then the power figures are likely to thrown well out of whack I'd imagine which might make them useless for you. The need to stick to the same resistance setting for an entire session might not apply to other turbo trainers perhaps, depending on how well the TrainerRoad software works with them.

As for ANT+ compatibility, the Flow doesn't support ANT+ that I know of so its display is entirely separate from the Garmin display and the TrainerRoad display.

If I remember correctly the Kurt Kinetic turbo trainers have a good reputation for calculating power accurately (it uses an algorithm so it's virtual power too). Might be worth digging into those. They also seem very compatible with TrainerRoad too from what I recall so even if the turbo trainer gives you good power info itself you could still benefit from the other advantages of TrainerRoad if you fancied. There is some useful info on the TrainerRoad website about various turbo trainers.

Briando

+1 for TrainerRoad.

Its the way to go.

Turbo + garmin speed & cadence sensor + ant stick and you are set for proper training sessions.

nordicb

I have one of these, it has power displayed on the display. I think it's a bargain.

http://www.donedeal.ie/bicycles-for-sale/for-sale/6053113

smacl

detones wrote: »

The tacx flow is electronic unit with a digital disply control. You just push a button to increase resistance. The flow shows this a %incline like climbing a hill. The display shows show speed, power and cadence. You can get an add on to connect all this to a pc and use the virtual reality interface.

I've also got the tacx flow, vr version, and while I love it, it has its limitations. I don't have a power meter for the bike, but even with calibration the speed it reports me doing on the VR is far better than I achieve on the road, so I'm guessing the power is similar. Results are consistent however, so once you're comparing against past performance it is fine. The other issue with the flow versus higher end tacx models is that it is limited in terms of gradient it can simulate, though this is more an issue for VR.

FWIW, I think the VR is a great incentive to pushing harder, as I usually use it in a mode where I'm racing against my previous best times on the same circuit, and will bust a gut to shave a second off here or there. My reported power output has also risen over time as a result.

Ribble were doing good deals on tacx prices last time I looked. Mine came from bike24.

fat bloke

The one I'm looking at is the Elite Qubo something. It's about 500 notes. I think you can set the power to a given wattage and it varies resistance to suit cadence, which is exactly what I want I think

MD1983

fat bloke wrote: »

The one I'm looking at is the Elite Qubo something. It's about 500 notes. I think you can set the power to a given wattage and it varies resistance to suit cadence, which is exactly what I want I think

at €500 you are buying an expensive turbo. just go the whole hog and buy a PM for her/your bike, what use is the power turbo to you when you are outside racing and would like to see power then. you will regret it and wish you had spent €200 on the turbo (normal one) and then get a power2max or something for reasonable money.

doozerie

fat bloke wrote: »

The one I'm looking at is the Elite Qubo something. It's about 500 notes. I think you can set the power to a given wattage and it varies resistance to suit cadence, which is exactly what I want I think

The Tacx Flow lets you set either a wattage figure or a resistance figure. I've never actually used the wattage option there so never looked into it but it might do what you are looking to do.

Mind you due to its general inaccuracy in absolute wattage terms, the wattage the Flow displays won't be a very reliable indicator of how much power it is truly forcing you to apply. I've found my Flow to be fairly consistent in the power figures it reports/displays but those figure don't match the figures either my Powertap or TrainerRoad showed at the same time (the Powertap and TrainerRoad figures were very close to each other though).

smacl

doozerie wrote: »

I've found my Flow to be fairly consistent in the power figures it reports/displays but those figure don't match the figures either my Powertap or TrainerRoad showed at the same time (the Powertap and TrainerRoad figures were very close to each other though).

Interesting. Did you notice if the Flow was in direct proportion the others or non-linear? Just wondering how far the figures for own sessions are from reality.

harringtonp

fat bloke wrote: »

Been using a powertap for over a year now, and sharing it with my significant other. This can make what can be a fraught relationship even fraughtier (frothier?) . Swopping the powertap wheel from bike to bike and swopping / setting respective bikes up on the turbo is becoming a pain so we could do with an easier solution. It's hard enough to box off an hour to yourself besides wasting time mechanicking.

Anyway, I caught her googling such things and figured some more research was needed. It seems to me that there are perfectly good turbo's for a couple of hundred quid, and then there are ridiculously expensive power measure ones for 2 grand, and then in the middle are multi-function things with all sorts of bells and whistles and which also claim to "measure" "power". There's a qubo one and a tacx one I think, and they're around like the 500 quid mark.

My gut tells me that they're a load o' boll0x , but does anyone here actually have one that could give us a heads up?

Myself and the mrs run the turbo ragged between us so this is something that will be used a lot and so it's worth or while getting something decent, and we are training with power and power metrics so we want something that will accomodate that. Basically I suppose what I'm saying is I don't want to start a powermeter haters v's the world thread, or be recommended the best lights for night training, or vouchers for a spinning class. :rolleyes::o

Tongue and cheek delivery of this post brought a smile my face

harringtonp

MD1983 wrote: »

at €500 you are buying an expensive turbo. just go the whole hog and buy a PM for her/your bike, what use is the power turbo to you when you are outside racing and would like to see power then. you will regret it and wish you had spent €200 on the turbo (normal one) and then get a power2max or something for reasonable money.

Power2Max from €858 including postage, Stages from £600

doozerie

smacl wrote: »

Interesting. Did you notice if the Flow was in direct proportion the others or non-linear? Just wondering how far the figures for own sessions are from reality.

It has been several months since I've done a turbo session but my memory of it is that it is non-linear. I think that at higher speeds/wattage, the Flow grew further out of synch but I can't recall exactly how far out it was at its worst.

I have read much the same said online though by people who compared their Flow to their power meter figures. Some of those online comments suggested that the Flow's power figures were pretty much useless as they found them to diverge by so much the more they increased their power output - from that it sounds like the issue may become more prevalent the stronger the rider is.

I plan to use the turbo this evening (bleugh!) so if I learn anything further from that I'll post back here.

MRJ

Well folks sorry to go off topic a bit, could anybody tell me how accurate TrainerRoad's virtual power meter is?

I signed up this morning and done an 8 minute test and was a bit shocked with the results. I use a Garmin Cadence Sensor and HR monitor and kept the resistance at level 4.

doozerie

MRJ wrote: »

Well folks sorry to go off topic a bit, could anybody tell me how accurate TrainerRoad's virtual power meter is?

I signed up this morning and done an 8 minute test and was a bit shocked with the results. I use a Garmin Cadence Sensor and HR monitor and kept the resistance at level 4.

Its accuracy depends. You need to select the appropriate device to match your specific turbo trainer - that bit is obvious, but what may be less obvious is that there may be more than one device listed for your turbo. In the case of the Tacx Flow they seemed to produce a number of devices as they worked their way towards one which produced reliable results. Perhaps they do likewise with other turbo trainers too.

In addition, you need to ensure that you calibrate your turbo properly first (ensure the tyre is the "right" pressure, that the pressure of the tyre against the turbo is "right", etc.), and you may have to set a particular resistance level on the turbo too (in the case of the Tacx Flow I have to set resistance of +2 to match the device that I select).

Best thing is to read up about your turbo trainer on the TrainerRoad website, they seem quite responsive to issues judging by what I've read on their before. Basically it all hinges on your particular turbo trainer, how it is set up, and what device file you select for it within TrainerRoad.

smacl

doozerie wrote: »

(ensure the tyre is the "right" pressure, that the pressure of the tyre against the turbo is "right", etc.)

This makes a huge difference in the tacx VR software too; over inflated tyre / too much pressure on the flywheel seems to increase the resistance and I'm guessing squeeze the bearings on the turbo unduly. Not enough and you get slippage, noise, and greater tyre wear. While I haven't mapped HR against power, the reported power output at higher resistance levels, seems much less than at lower levels. e.g. I find on flat sections on the VR (low resistance) I can happily hold 300w, but struggle to hold 250w on inclines (high resistance). I would have thought that if you gear down to have the same cadence in both scenarios, similar effort would generate similar power levels, but it doesn't seem to work like that. Must stick on a heart rate monitor at some point and graph heart rate against power.

MRJ

Yeah tyres are inflated to correct pressure and the turbo is a Tacx Satori which is listed on website, the default FTP setting for the virtual power meter was at 200w but when i finished the test it was telling me that my FTP should over 400w. I suppose the only way of checking is to do the same test again.

doozerie

@smacl, It has been a few months since I compared the power figures from TrainerRoad against those from my Powertap hub, and there has been at least one update of the TrainerRoad software since then. So I can't be sure they match like they did before but I'm going to assume TrainerRoad is no less accurate now.

On that basis the figures from the Tacx Flow are not linear relative to "real" power. When TrainerRoad displayed 95W the Flow displayed 110W, when TrainerRoad display 190W the Flow displayed 220W, there or thereabouts. I didn't pay much attention when I briefly pushed the wattage above 190W but it seemed like the difference widened further very quickly as soon as I did. This seems to match with some online anecdotes I've read whereby the higher the power output the less reliable the Flow's measurements become.

doozerie

@fat bloke, Another brand of turbo trainer that might be worth considering is Cyclops. When I got my bike fit done a few years ago the fitter used a Cyclops turbo as it allowed him to measure any differences in power output as he adjusted my position on the bike. I asked him at the time whether he found it a good turbo trainer and his answer was yes, and if I remember correctly he also said that he thought its power figures were reasonably good. I wouldn't assume it estimates power accurately based on just that but it would make me look into the brand further if I was buying a turbo again.

J Madone

Have a lemond trainer for over 2 years now, it's the single best piece of cycling equipment I have. There Is no tyre slip or tyre pressure deviations because you remove your rear wheel, they are expensive initially but after 1 year it owed me nothing. Most of my training is intervals in the pain cave. Originally had the power pilot to measure and display power but since I got a quarq crank I sold the power pilot and use trainer road with it. When I had power pilot and power crank there was very little difference in power outputs if I had both displayed. No way I would change from the Lemond revolution. You can stand, sprint and do really high cadence work and it is solid as a rock. If you had the cash get one!

Beasty

J Madone wrote: »

If you had the cash get one!

If you have the cash and space, the best "power" trainer you can get, by a country mile, is a Wattbike...

J Madone

Beasty wrote: »

If you have the cash and space, the best "power" trainer you can get, by a country mile, is a Wattbike...

Disagree, I'm on my road bike which I have been fitted on, I'm in the same position as when I'm on the road with my saddle which im used to, using my gear ratios , cranks and pedals and if i want to train on tt bike takes 30 seconds to swap, I like training on my bikes rather than the feeling of sitting atop of a machine.
The lemond is quite loud is the only drawback in my opinion

cantalach

doozerie wrote: »

On that basis the figures from the Tacx Flow are not linear relative to "real" power. When TrainerRoad displayed 95W the Flow displayed 110W, when TrainerRoad display 190W the Flow displayed 220W, there or thereabouts. I didn't pay much attention when I briefly pushed the wattage above 190W but it seemed like the difference widened further very quickly as soon as I did. This seems to match with some online anecdotes I've read whereby the higher the power output the less reliable the Flow's measurements become.

The gap may be widening in absolute terms but based on the figures you've quoted there, it is consistent in relative terms. 95W vs 110W is 15.78%, and 190W vs 220W is 15.78%.

I've owned a Flow for a couple of years and found it to be a useful training tool. It certainly isn't accurate, i.e. the power displayed does not correspond to actual power. Crucially though, independent testing has found it to be reasonably precise, i.e. the power displayed from one day to the next will be consistently inaccurate. The distinction between these terms is important. From a training perspective, precision is key because all that really matters is comparison to your former self on the same turbo. Accuracy only really comes into play if you need to compare with power data coming from another source.

A big proviso though in terms of the Flow's precision is that you have to calibrate it every time when the unit has warmed up. This isn't such a big deal because the cyclist needs to warm up too! So you can warm up for 15 minutes and then take 30 seconds out to calibrate the Flow.

However, the criticality of doing this calibration every time to ensure precision is what makes me very suspicious of TrainerRoad when used with most turbos. The virtual power number is calculated using a model-specific formula that is based purely on speed, but there is no coast-down calibration facility. For this reason, when I recently had to buy I second turbo (wife has taken over the Flow!), I opted for a Kurt Kinetic Road Machine. One of the big selling points of the Road Machine is that it apparently has a very consistent power curve from day-to-day, i.e. calibration isn't necessary.

Junior

J Madone wrote: »

Disagree, I'm on my road bike which I have been fitted on, I'm in the same position as when I'm on the road with my saddle which im used to, using my gear ratios , cranks and pedals and if i want to train on tt bike takes 30 seconds to swap, I like training on my bikes rather than the feeling of sitting atop of a machine.
The lemond is quite loud is the only drawback in my opinion

Ed have you used a Watt Bike for prolonged periods ? With the new moulded bars I've found it damn close to riding a road bike.

J Madone

Junior wrote: »

Ed have you used a Watt Bike for prolonged periods ? With the new moulded bars I've found it damn close to riding a road bike.

Don't doubt they are good, just not my exact setup,Lemond handy for warmups for before tts also as its fairly mobile.
Looks like your doing a bit at the moment Junior?

Beasty

J Madone wrote: »

Disagree, I'm on my road bike which I have been fitted on, I'm in the same position as when I'm on the road with my saddle which im used to, using my gear ratios , cranks and pedals and if i want to train on tt bike takes 30 seconds to swap, I like training on my bikes rather than the feeling of sitting atop of a machine.
The lemond is quite loud is the only drawback in my opinion

I am referring specifically to trainers that accurately measure power. As Junior says you can get pretty close to a road set-up with a Wattbike, but that's not its primary function, and you cannot properly replicate "real" riding on any stationary trainer. It's the ability to accurately recond analyse power that this thread is about.

Don't claim to have tried the LeMond, but from what I understand accurate power recording/analysis is not one of it's main features

fat bloke

Decided against it in the end, though I was warming to the idea. Got a regular tacx to replace our nearly ten year old, old one, and the mrs is gonna save up for her own powertap.