Kurt Kinetic computer

kant314

so what you're trying to say is that the formula is for MPH.

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wiredued

Keep in mind the the number entered into the computer is 1917 which corresponds to .019168 Piotr had to correct me about a year ago because I took the typo formula from the KK web site.

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Romans 5:10 For if, when we were enemies, we were reconciled to God by the death of his Son, much more, being reconciled, we shall be saved by his life. http://www.earnharts.com/html/reala...ecific.asp?id=3

wiredued

It is in mph but if you ad a column on the left to an Excel sheet for kph with the formula to convert to mph you could get kph easy enough.

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Romans 5:10 For if, when we were enemies, we were reconciled to God by the death of his Son, much more, being reconciled, we shall be saved by his life. http://www.earnharts.com/html/reala...ecific.asp?id=3

frenchyge

D'oh! I thought I remembered there being a typo involved in there somewhere.

I recently had to send my PT hub in for repair and have been using the speed curve for the past couple weeks when I discovered that my hub had been reading about 35w below what the speed *formula* would predict. I remembered some old conversation about that formula, but couldn't remember what came of it since I normally use my power hub. Looks like those extra 35w aren't coming my way after all.

Edit: Hmmmm..... difference is only a couple watts (between the two formulae). Hopefully they'll calibrate my hub while they have it.

I wonder if Kinetic uses a rolling resistance on that curve, or if that's purely the power to drive the unit? Could mean another 10-20 watts at the cranks for all the 300w-club hope-to-bes.

wiredued

I think it only dropped my FTP by about 4 watts when I made the correction.

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Romans 5:10 For if, when we were enemies, we were reconciled to God by the death of his Son, much more, being reconciled, we shall be saved by his life. http://www.earnharts.com/html/reala...ecific.asp?id=3

squidwranglr

Just so you know (and assuming I'm not misunderstanding what you're describing), the compression polymer with conductive strips is a very common and industry-accepted way of passing signals from circuit boards to small LCD screens:

http://www.shinpoly.co.jp/business/...pe_e/zebra.html

I can tell you, for example, that Polar heart rate monitor and cycling watches also use the same method. This technology has been around for decades and is very mature, so I very much doubt is the fundamental issue with the Kurt Kinetic power computer.

And, for disclosure's sake, I'm a very happy Kurt Kinetic Road Machine user of a number of years, but I don't own the power computer (I used to use a laminated power curve I prepared in Microsoft Excel using the published formulas).

Berend

Ade Merckx

Hey John I just read your blog that a shame about you needing a knee op. Are you going to see how effective your training (311wattFT) has been by doing 1 or 2 races before you go under the surgeons knife? There's lots of 4th cat and 3rd cat races comming up and its a chance to really test yourself in the real' world. With that kind of sustainable power under the hood you should be fairly comfortabe. If you give me a shout I'll even come and join you

kant314

Hi Ade,

Yes, I'd like to try a few before I go under the knife....assmuning the weather warms up a bit.
I've got a business trip to Hong Kong coming up soon though. I'll be away for a couple of weeks with that, so that means 2 more weeks training lost.

cheers
John

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Ade Merckx

Ok lets see how it worksh out, even just a 40min - 60min job at Hillingdon would be a nice psychological boost. Having ridden with the 19mph group quite a bit I'm sure your pack riding skill are ok. Have a look on http://www.britishcycling.org.uk/we...ventsfuture.asp in the south east region and let me know if you can make any of the races. If you post on the ACC site perhaps others may come along too. Anyway whatever happens keep training when you can. Its great to see you can now comfortably bang out 3 x 20's when last year you wouldn't go near a 2 x 20 with the proverbial barge pole

kant314

Hi Ade,

It's all about the mindset, I think.
When I started, I found it harder mentally rather than physically to do 20 mins on a TT.
Once you get used to the pain you kind of become accustomed to it or are better able to deal with it and see a session through..
That's my take on it , anyway.

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Ergoman

I hate to discourage you all who are using the KK computer or are doing calculations or using the KK curves to determine your power...BUT, there's no way you're going to get accurate results. There are at least two reasons:

1. The KK machine itself is affected by temperature. As it warms up and cools down, power readings will vary significantly.

2. The power required to turn the KK is greatly influenced by the clamping pressure to the wheel. Further, it's very difficult to get the clamping pressure exactly the same every time you ride.

Finally, the KK computer is nothing more than a cheap speedometer and the reading it gives assumes a constant clamping pressure, a standard temperature for the trainer and no wheel slip plus and accurate calibration for wheel size. These conditions are not likely to occur with any predictability.

In general, if you want accurate power, get a real power meter. The KK computer can easily be off by 20% or more in the 200 to 300 watt range, and even more than that at lower powers.

frenchyge

They do shift during the warmup and cooldown, but are actually pretty stable (as advertised) in between. See this little experiment that I did with mine: http://www.cyclingforums.com/showpo...16&postcount=56


I think the folks that are serious about using their KK computers do a coastdown test before each ride to try to standardize those factors, but you are correct. Most just seem to be looking for something cheap, yet more consistent than HR.

Yojimbo_

Here's something I found re the KK power calibration. This is a comparison against a PT power meter.

It looks surprisingly good to me.

http://www.planet-x-bikes.com/triat...age&PAGE_id=189

kant314

where do you get those figures from?

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