Measuring power... what do I need?

SkyBlueKangaroo

Hopefully this will be a simple one to answer. I'm looking at getting a turbo trainer to do power training. But am I right in thinking that I need both a trainer (to provide the work/resistance) AND also a power hub on my bike to measure my power output?

Or do the trainers themselves measure and transmit power readings? Or does it depend on the model, etc?

Can anyone recommend a particular set up they use. I'm looking primarily at doing steady cadence 2x20's as opposed to out-of-the-saddle sprint stuff. Quiet would be nice too!

Given the cost of a power tap or similar, Is a simple and permanent option to just get an indoor spin bike which measures power, such as the Cycleops 300PT? Pricey?

Or should I use the exercise bike at my gym which gives a power reading, but has me squirming on my a*se after 20 mins because of the unfeasably uncomfortable DFS leather sofa-like saddle....

willbevan

option im looking at is rentinga powertap hub,the basic one to start with till the SL2.4 is compatible with teh 705..

8GBP a week from here:

http://www.cyclepowermeters.com/powerme ... l-24-c.asp

Not affiliated with them in any way,but i fancy trying a power meter over the winter...

Alex_Simmons/RST

SkyBlueKangaroo wrote:

Hopefully this will be a simple one to answer. I'm looking at getting a turbo trainer to do power training. But am I right in thinking that I need both a trainer (to provide the work/resistance) AND also a power hub on my bike to measure my power output?

Or do the trainers themselves measure and transmit power readings? Or does it depend on the model, etc?

Can anyone recommend a particular set up they use. I'm looking primarily at doing steady cadence 2x20's as opposed to out-of-the-saddle sprint stuff. Quiet would be nice too!

Given the cost of a power tap or similar, Is a simple and permanent option to just get an indoor spin bike which measures power, such as the Cycleops 300PT? Pricey?

Or should I use the exercise bike at my gym which gives a power reading, but has me squirming on my a*se after 20 mins because of the unfeasably uncomfortable DFS leather sofa-like saddle....

All of the above exist and are options.

Which is best depends on your personal circumstances (type of riding, training time, equipment, location, budget etc).

If you are looking at the price of a power meter / trainer combo, then IMO, something like a Powertap Pro with a Kurt Kinetic trainer would make an excellent combination, providing accuracy, reliability, indoor and outdoor power training options on the same bike.

Just don't buy a crummy indoor trainer unit, you'll hate riding it.

FORUM EXPERT

TACX FLOW IS WAT YOU WANT.

DOES WHAT YOU ARE ASKING

SkyBlueKangaroo

Thanks Mr Expert - had a quick look, it's been reviewed on BikeRadar. So I could just slot any old bike bought on eBay onto this peice of kit, with a training tyre, a decent saddle and pedals, and that's my indoor power training rig, yes? Nothing else required?

Looks like I could get away with spending well under 500quid. Sounds better than 1200quid on the Cyclops. Thanks again.

Kléber

Why bother with a turbo trainer powermeter? I mean you can get a good turbo and so long as you use the same gear, then just use a cheap speedometer working of the rear wheel and you will see the same information as greater speeds equal increased power?

Ergometers are great but really come into their own when you are out on the road as a watt is a watt regardless of traffic, headwinds or your position on the bike. Sit indoors and none of these variables come into play...

SkyBlueKangaroo

Thanks for the reply Kleber, I see where you are coming from, but I do want to power as a measurement of performance, and I don't want to be restricted to using the same gear - when my fitness improves then my speed will increase, then so will my cadence in the same gear, until it does not bear any resemblance to what I do out on the road.

My question was whether I needed to get a trainer AND a power tap or similar. Looking at the Tacx it would appear this is a complete solution. Just what I am looking for.

Obviously if there are alternatives to the Tacx that are better or priced attractively, then I'm interested to hear comments.

Thanks again.

eh

Kleber is exactly right, just get a rear wheel mounted computer preferably one with cadence. As you get fitter you should be able to ride the same cadence but on larger gears.

If you want to get serious then you need a setup that can be used outdoors as well. But to be honest if you were to go this route I'd suggest either getting a coach or do a large amount of reading about power training, otherwise you'll be wasting your investment.

SkyBlueKangaroo

So is there a benefit of having a rear wheel computer and trainer, compared to the Tacx product? Because by the look of it, the Tacx kit also measures speed and cadence... How does this rear wheel computer measure your power?

Alex_Simmons/RST

SkyBlueKangaroo wrote:

So is there a benefit of having a rear wheel computer and trainer, compared to the Tacx product? Because by the look of it, the Tacx kit also measures speed and cadence... How does this rear wheel computer measure your power?

It doesn't. It simply converts a given speed to a power number based on a typical power - speed relationship for that trainer. That's OK as long as the trainer in question has:

i. a repeatable power-speed relationship, IOW no variables affecting this relationship are changed from ride to ride (things like tyre clamping pressure, tyre pressure, type of tyre etc which can affect it);

ii. a limited amount of drift in the power-speed relationship as the unit varies in temperature as it is ridden (both as it warms up and depending on the load it is managing); and

iii. a consistent slope in the power-speed relationship as the unit changes temperature when ridden.

All trainers exhibit the above variations to some degree (even the programmable ones that measure power via an electro braking system as opposed to using roller speed), and some are better than others. For some once warmed up they are pretty consistent. Others are not so good.

Does it impact training methods? In general, not really but I would place some sizeable grains of salt on the actual numbers produced by such a unit. Consistency and repeatability are the most important elements. Accuracy is important if you intend to use that data for other analyses or to compare with a power meter in the future.

SkyBlueKangaroo

I just want a set up that allows me to ride intervals in a constant environment, ie. indoors, so that I can track/develop my FTP. The metering can be wrong by any percentage, as long as it is always wrong by that percentage - as you say Alex "consistency and repeatability" are the key words.

This Tacx product seems to fit the bill. Just hook up a cheap bike, and away I can go. And all for less than half the cost of the Cyclops spin bike I read about.

Thanks for everyones replies.

eh

But a basic Tacx coupled with a rear mounted computer will allow you to do what you want for less. Although perish the thought it actually requires you to do a little thinking and understand what you are trying to do :roll:

andrewgturnbull

eh wrote:

But a basic Tacx coupled with a rear mounted computer will allow you to do what you want for less. Although perish the thought it actually requires you to do a little thinking and understand what you are trying to do :roll:

Hi there.

The main benefit of the Flow is in it's ergo mode. Yes you can use an ordinary turbo and keep the speed at a certain level, but the ergo mode forces you to keep 'on it' for every pedal stroke.

This means there is no hiding during an interval, not even for half a second.

Cheers, Andy