Indoor trainer just for bad weather?

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Re: Indoor trainer just for bad weather?

Postby sb944 » Tue Apr 02, 2013 12:39 pm

Xplora wrote:I've done my FTP test, got some rough and ready figures and a set up to work from. 290W FTP at 72.5kgs was just under 4w/kg. It's no power meter, but it's a starting point. Doing the 30 minute test was very helpful. Basically started in one gear, lifted one gear at 10 minutes, and then pounded it out. There is a very real logarithmic perception of pain when you know you have to reach a certain point, and your body just turns the screws on your mind as you try and push through.

BTW I basically aimed at a particular cadence for the 30 minute test, and took the resulting "distance" and multiplied by 2 to give a speed per hour and then ran Kurt's formulae. This hopefully was a nice steady way to generate the power for the timeframe. I've GOT to learn to back off before the paceline crush down Windsor Road... the body has limits, and I'm using them :idea:


Wow, 4W/kg is excellent, especially for an initial test. My 2nd run was 10% higher FTP than my first, and I still might have a little more in the tank for next time I do the test. This time I had HRM, cadence and virtual power showing for a 2x 20 minute test, which is warmup, 20 minutes (AT) FTP, 2 minute break, then 20 minutes (AT) FTP. It is very clinical. Without all the distractions of the road, you really can focus on these readings and see some interesting things. I noticed my power really drops quickly if I stop paying attention for a few seconds. Also while I could maintain the power for the whole 40 minutes, and even ended up faster over the last 5 minutes, my HR kept slowly going up the whole session and was 20BPM higher towards the end. I also found cadence was the easiest thing to focus on to maintain the right watts.

It's not 100% accurate, but as long as it's repeatable, it's close enough for your purposes. I just bought a quality floor pump to replace my cheap innacurate 100psi one. I've always wanted one for getting my road tyres to the right pressure, but now it's more important, as I'd hate to think I'd done an hour of training at 10% lower watts because of inconsistant pressure. I'm now setting it up to roughly 100psi, 4 full turns from touching. Once I get the new pump, I'll try 120psi and 5 full turns. Then I'll have a more accurate base FTP, then onto one of the programs to improve TT times.
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by BNA » Tue Apr 02, 2013 2:22 pm

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Re: Indoor trainer just for bad weather?

Postby Xplora » Tue Apr 02, 2013 2:22 pm

I do some very serious kms for a mere mortal, the 4W is a long way from the goal... I think I realistically need to pump that to about 5W over the next 12 months to be where I want to be (awesome without use of drugs, and not needing private health cover for the physiotherapist bills and nurofen addiction). I have plenty of room for improvement. I get slaughtered by the A grade racers in the paceline home.

I agree that it's clear when you have extra in the tank. Friel said do 30 minutes, and revise your pacing after 10 minutes, then each 5. I knew I would struggle with the 36kmh but it's a threshold test, not a "beat your mate to the top and try and ride 30kms to home" test. I have a very good feeling about how long I can survive once I get towards the end of my tank, but I am a long way from working how big the tank really is, and managing it all in the hour before the light flashes and I am looking for wheels to suck.

I'll have to pick up a HRM soon, mainly for my wife who needs to begin a base phase LOL
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Re: Indoor trainer just for bad weather?

Postby MrDerrickC » Tue Apr 02, 2013 5:45 pm

sb944 wrote:Two reasons. A trainer tyre can withstand the heat a trainer builds up with heavy use, and also it's also got no tread pattern, which helps avoid slipping better and any false readings of speed/power. There are plenty of stories around the net of people chewing through good tyres in one spirited trainer session, then getting 10000 miles plus with a trainer tyre.


Ahhhhh! Thanks! So that means I am better off buying a new rear wheel with proper training tyre on it for dedicated use on the trainer. More spending! Yay! I'm guessing any basic wheel will do?
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Re: Indoor trainer just for bad weather?

Postby Lukeyboy » Tue Apr 02, 2013 6:10 pm

MrDerrickC wrote:
sb944 wrote:Two reasons. A trainer tyre can withstand the heat a trainer builds up with heavy use, and also it's also got no tread pattern, which helps avoid slipping better and any false readings of speed/power. There are plenty of stories around the net of people chewing through good tyres in one spirited trainer session, then getting 10000 miles plus with a trainer tyre.


Ahhhhh! Thanks! So that means I am better off buying a new rear wheel with proper training tyre on it for dedicated use on the trainer. More spending! Yay! I'm guessing any basic wheel will do?


If you got some spare unused tyres (cuts etc) laying around whip them out and use them. Do a quick repair job to seal the cuts/don't bother at all. If you have any punctured tubes you can give them a new home aswell :P If I lose a tyre/tube when on the road I keep them and they get reused on trainer duties. No need to be concerned about wear as you.... well in my case I have plenty of cut/damaged sidewall tyres built up overtime... that have been reserved for trainer duties. You could even pop into your local lbs and see if they have any dud tires.
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Re: Indoor trainer just for bad weather?

Postby MrDerrickC » Tue Apr 02, 2013 6:54 pm

Thanks for the advice! Will see if the LBS has some old tyres, I do not have any myself as I have only recently started cycling.

So to save myself time, as I assume people don't change the tyres off their wheel all the time and just have a spare wheelset, the cheapest option seems to be Shimano R500? I currently have ultegra wheels and groupset, in terms of cassette for the training wheel can I just use a cheaper cassette or would it be better to get the same ultegra cassette? Sorry if some of the questions seem a bit silly :oops:
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Re: Indoor trainer just for bad weather?

Postby george-bob » Wed Apr 03, 2013 8:57 am

I gave the trainer road 8 minute test a whirl this morning, didn't pay any attention to the numbers at the time then afterwards it gave me an FTP of 587W, at 80kg that is an unlikely 7.33 W/kg! I suspect my tyre is slipping, I will try to sort it out tonight and try the test again tomorrow.

Alternatively I could try and find a pro team to join :P
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Re: Indoor trainer just for bad weather?

Postby Xplora » Wed Apr 03, 2013 9:18 am

What speeds were you pulling? I was only doing 32-36kmh the whole 30 minutes I did.... about a dozen accelerations to get the cadence from 84 to 90 maybe... 8 minutes is going to give you a much higher power and a lot more ability to push harder if you're slowing. Worth trying again with a 20 minute test?
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Re: Indoor trainer just for bad weather?

Postby sb944 » Fri Apr 05, 2013 9:27 am

On a Kurt Kinetic Road Machine, TrainerRoad suggests you pump tyres to 120psi, then turn the knob 5 full turns after tyres touch the resistance wheel.

At that point, they seem to just use the resistance formula on KK's website, so 36km/h=330W and 40km/h=430W. To get FTP from an 8 minute test, you probably reduce the 8 minute watts by about 10%, so that would be roughly 47km/h for 640W for the 8 minute test.
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Re: Indoor trainer just for bad weather?

Postby Xplora » Fri Apr 05, 2013 10:22 am

I feel a bit confused about the whole "lets do short intervals" for FTP testing... the perfect test outlined by Joe Friel is simply an hour long TT, for both power and heart rate... because that's what FTP's definition is. The max you can do over an hour. Some people are going to react differently over the hour, and trying to shorten that can only introduce error. I was a bit surprised that my calculations for FTP changed by 2w when I included the extra 4 seconds from my 30 minute session. That's a big deal if you are trying to track a gain of perhaps 5w every month (at the start of your training).

I'm close to just getting a power meter LOL
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Re: Indoor trainer just for bad weather?

Postby Alex Simmons/RST » Fri Apr 05, 2013 12:46 pm

sb944 wrote:On a Kurt Kinetic Road Machine, TrainerRoad suggests you pump tyres to 120psi, then turn the knob 5 full turns after tyres touch the resistance wheel.

At that point, they seem to just use the resistance formula on KK's website, so 36km/h=330W and 40km/h=430W. To get FTP from an 8 minute test, you probably reduce the 8 minute watts by about 10%, so that would be roughly 47km/h for 640W for the 8 minute test.

An 8-minute test for FTP?

If perhaps you combine it with a 3 minute test and a 25-minute test and apply the Critical Power model as described by Monod & Scherrer, you'll get better estimate of FTP, but the ratio of 8-min power to FTP will be quite a range, and can vary quite a bit for an individual depending on many things.

I'd be interested to know the sensitivity of *actual* resistance is to how hard the resistance knob is turned on various trainers. IOW how it affects the actual speed-power relationship. On my trainer, minor variations (e.g. 1/16th of a turn) in the tightness of the control knob can have quite an impact on the actual resistance load.
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Re: Indoor trainer just for bad weather?

Postby Xplora » Fri Apr 05, 2013 2:17 pm

That was something I noticed on your blog, Alex - most of the data was blahblah % +/- 3%. If we're expecting errors in the data, that says a lot about the process, doesn't it, if you are then going to then use another estimation method, which will in turn let you use that number to estimate your workload in your general training?
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Re: Indoor trainer just for bad weather?

Postby warthog1 » Fri Apr 05, 2013 2:21 pm

Alex Simmons/RST wrote:I'd be interested to know the sensitivity of *actual* resistance is to how hard the resistance knob is turned on various trainers. IOW how it affects the actual speed-power relationship. On my trainer, minor variations (e.g. 1/16th of a turn) in the tightness of the control knob can have quite an impact on the actual resistance load.


I think in that case he is talking about screwing the roller onto the tyre by 5 full turns. AFAIK the kurt has fixed resistance.
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Re: Indoor trainer just for bad weather?

Postby Alex Simmons/RST » Fri Apr 05, 2013 5:25 pm

warthog1 wrote:
Alex Simmons/RST wrote:I'd be interested to know the sensitivity of *actual* resistance is to how hard the resistance knob is turned on various trainers. IOW how it affects the actual speed-power relationship. On my trainer, minor variations (e.g. 1/16th of a turn) in the tightness of the control knob can have quite an impact on the actual resistance load.


I think in that case he is talking about screwing the roller onto the tyre by 5 full turns. AFAIK the kurt has fixed resistance.

That's what I mean, the knob that controls how hard the roller presses against the tyre.

I find it very difficult to believe that any trainer would be insensitive to that adjustment.
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Re: Indoor trainer just for bad weather?

Postby Xplora » Fri Apr 05, 2013 6:23 pm

Alex Simmons/RST wrote:
warthog1 wrote:
Alex Simmons/RST wrote:I'd be interested to know the sensitivity of *actual* resistance is to how hard the resistance knob is turned on various trainers. IOW how it affects the actual speed-power relationship. On my trainer, minor variations (e.g. 1/16th of a turn) in the tightness of the control knob can have quite an impact on the actual resistance load.


I think in that case he is talking about screwing the roller onto the tyre by 5 full turns. AFAIK the kurt has fixed resistance.

That's what I mean, the knob that controls how hard the roller presses against the tyre.

I find it very difficult to believe that any trainer would be insensitive to that adjustment.

This is precisely the reason why it can only be "X watts with Y psi in the tyre and Z amount of turns"... the internal resistance in the fluid could be assigned the formula, but the actual resistance? Only a real power meter owner could tell you. My comment about the 290W FTP I pulled on the Kurt is only that - a 290W FTP on the Kurt. Good for intervals, GREAT for my wife (who is far from anything resembling base fitness yet), less than nothing on the road :D The main benefit of Kurt's Road Machine is strong correlation to air resistance over 0-80kmh and doesn't crap out with temperature increase. I think anyone expecting more than that has potential to be quite disappointed :shock:
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Re: Indoor trainer just for bad weather?

Postby sb944 » Wed Apr 10, 2013 11:13 am

I bought an expensive floor pump (way overdue), so can now actually pump the tyres to 120psi. I then put some tape on one part of the knob. Spin the rear wheel and move the knob in until it touches the tyre, note where the tape is pointing. Turn it 5 full turns with the tape pointing at exactly the same point. This is not much effort to get repeatable wattage figures, so I'm happy with this for now.

Interestingly, I did the 2x 20m test on the trainer, and held an average of 36.2 km/h over the 40 minutes of riding, only a 2 minute break in between. I then did my first 25km TT at Calga (hilly course with little wind, standard road bike, nothing aero), and averaged 36.1km/h. This is amazingly close, I think they've done a great job simulating the road speeds.

Now to get the engine to produce 37km/h...
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Re: Indoor trainer just for bad weather?

Postby Xplora » Thu Apr 11, 2013 2:48 pm

nice... bear in mind your 10km commutes are almost worthless for improving FTP... i've been doing 20km for 12 months and I had to do aerobic centuries on a regular basis (1-2 times a week) to get any proper fitness improvement. You have to chase KOMs to get the sprints stronger... it's messed up and I've been drinking energy drinks :shock:
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