Why power measurement is important

The foundations for successful riding

Re: Why power measurement is important

Postby Aushiker » Sun Jan 24, 2010 1:22 pm

twizzle wrote:I STILL write in COBOL from time to time. :roll:


I thought it had died out. I guess still some mainframe COBOL programs around ... Is that what you are working in?

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by BNA » Sun Jan 24, 2010 2:17 pm

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Re: Why power measurement is important

Postby twizzle » Sun Jan 24, 2010 2:17 pm

Yep.

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Re: Why power measurement is important

Postby clack3rz » Mon Jan 25, 2010 8:17 am

Alex Simmons/RST wrote:However, you'll need to choose a rim that uses standard spoke holes and an even L-R spoke count.


So *any* manufacturer wheel as long as there is a std spoke count and even L-R?
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Re: Why power measurement is important

Postby twizzle » Mon Jan 25, 2010 9:00 am

clack3rz wrote:
Alex Simmons/RST wrote:However, you'll need to choose a rim that uses standard spoke holes and an even L-R spoke count.


So *any* manufacturer wheel as long as there is a std spoke count and even L-R?


You need to check the hub first, they come in limited versions, ie. 'Comp' is only available in 32 spoke, some of the others are available in 24 spoke.
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Re: Why power measurement is important

Postby clack3rz » Mon Jan 25, 2010 9:20 am

twizzle wrote:
clack3rz wrote:
Alex Simmons/RST wrote:However, you'll need to choose a rim that uses standard spoke holes and an even L-R spoke count.


So *any* manufacturer wheel as long as there is a std spoke count and even L-R?


You need to check the hub first, they come in limited versions, ie. 'Comp' is only available in 32 spoke, some of the others are available in 24 spoke.


Thanks Twizzle.
Is there any sites where I can read up on building wheels with PT Hubs etc? I'll probably get the build done, but want to source all the parts myself - will try for secondhand parts first.
I'll obviously need to get another set of wheels (currently using Fulcrum's Racing 7's) and want to ensure I get the *right* ones once I start sourcing.

I was looking to upgrade my ride, but I'm thinking that I my invest the money into my training (using power) and then try out some crit racing before I upgrade the ride.
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Re: Why power measurement is important

Postby twizzle » Mon Jan 25, 2010 9:39 am

Download the manual, it gives the basics. Because the hub feeds power to the non-drive side instead of the drive side (torque tube is free-floating on the cassette side), the non-drive side needs to be built cross-3, and tensioned properly. I had my first wheel built as a DTSwiss RR1.2, it's got ~3,500 km without an issue so far... except when I bent a spoke (caught the wheel putting the bike on the trainer while the wheel was spinning) and having to straighten the spoke and true the wheel afterwards.

Edit: multiple typo's.
Last edited by twizzle on Mon Jan 25, 2010 10:35 am, edited 1 time in total.
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Re: Why power measurement is important

Postby clack3rz » Mon Jan 25, 2010 10:05 am

Thanks - will check out the manual.
I'll look out for a suitable rim/wheel in the meantime. I'll get it built by the LBS anyway. I'll look out for a secondhand one - unless I find something suitable new.
Obviously getting the whole package would be the easiest but I need to keep the cost down as much as I can.....

EDIT: Apologies for the hijacked thread.....
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Re: Why power measurement is important

Postby Aushiker » Mon Jan 25, 2010 12:00 pm

clack3rz wrote:EDIT: Apologies for the hijacked thread.....


Hi

I don't think you have anything to apologise for. I found your question and the information that came from them interesting.

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Re: Why power measurement is important

Postby clack3rz » Mon Jan 25, 2010 12:08 pm

Aushiker wrote:
clack3rz wrote:EDIT: Apologies for the hijacked thread.....


Hi

I don't think you have anything to apologise for. I found your question and the information that came from them interesting.

Andrew


Thanks - I just dislike hijacking OP's threads......
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Re: Why power measurement is important

Postby Aussiebullet » Tue Jan 26, 2010 8:08 am

[quote="clack3rz"]
Is there any sites where I can read up on building wheels with PT Hubs etc? I'll probably get the build done, but want to source all the parts myself - will try for secondhand parts first. [quote]

If you head over to the "weight weenies" web site in the road section there is a "sticky at the the top of the page called the wheelbuilding thread, it is a gold mine for newb wheelbuilders and experianced builders for that matter,
it has loads of info on building pt wheels from arguably the "best" wheel builders in the world if there is such a thing lol.
l usually buy rim, spokes, nipples and hub of choice, grease nipples and threads then lace them up and get any LBS to tension/true them up for ~$30. I've laced up a pt wheel myself (24h niobium 30 rim) they are no diff to any other hub just be shure to do at least 2 cross on the non drive side,
Mine is still going strong with 30'000 + kms on it!
Its easy and cheap, the cost can blow out a bit though if you get LBS to order rims, spokes etc and get them to lace it up and build it from scratch.

Have fun :wink:
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Re: Why power measurement is important

Postby clack3rz » Wed Jan 27, 2010 6:16 am

Aussiebullet wrote:If you head over to the "weight weenies" web site in the road section there is a "sticky at the the top of the page called the wheelbuilding thread, it is a gold mine for newb wheelbuilders and experianced builders for that matter,
it has loads of info on building pt wheels from arguably the "best" wheel builders in the world if there is such a thing lol.
l usually buy rim, spokes, nipples and hub of choice, grease nipples and threads then lace them up and get any LBS to tension/true them up for ~$30. I've laced up a pt wheel myself (24h niobium 30 rim) they are no diff to any other hub just be shure to do at least 2 cross on the non drive side,
Mine is still going strong with 30'000 + kms on it!
Its easy and cheap, the cost can blow out a bit though if you get LBS to order rims, spokes etc and get them to lace it up and build it from scratch.

Have fun :wink:


Hi - Will check out the forum - thanks.
I'll probably have to get another wheelset - I currently have Fulcrum Racing 7's (red) and it'll be hard going to get a similar rear wheel alone to match the front :(
Pity I haven't had these long, and they're a good training wheel (a little on the heavier side) but a good wheel nonetheless.
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Re: Why power measurement is important

Postby brentono » Wed Jan 27, 2010 9:17 am

Since we are well OT, now. :roll:

clack3rz wrote:
a good training wheel (a little on the heavier side)

:shock:

Boris "the Blade" Yurinov: [referring to the gun he sold Tommy] Heavy is good, heavy is reliable.
If it doesn't work … you can always hit them with it. :lol:

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Re: Why power measurement is important

Postby JV911 » Thu Apr 29, 2010 1:05 pm

Alex Simmons/RST wrote:One could get going with a new quality power meter for under A$1,000 if they wanted, or much less for 2nd hand


anyone got one kicking around?
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Re: Why power measurement is important

Postby twizzle » Thu Apr 29, 2010 1:28 pm

Keep an eye on EBay - you get them turning up from time to time, but not usually priced well.

Or just buy a new 'Comp' kit from Excel - about $650 to your door (depending on exchange rate), then you need to find an appropriate rim and get it built. Might be cheaper to get Excel to send you a built wheel, takes it to about $950 - $1K, but I've put lots of K's on my built wheel and it was a really well built wheel. Unlike my locally built one which isn't quite round, although it has stayed true.
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Re: Why power measurement is important

Postby donncha » Thu Apr 29, 2010 4:01 pm

Also, competitivecyclist.com in the US are doing a Comp built into a DT wheel for US$650 which might be worth checking out.
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Re: Why power measurement is important

Postby JV911 » Thu Apr 29, 2010 4:17 pm

donncha wrote:Also, competitivecyclist.com in the US are doing a Comp built into a DT wheel for US$650 which might be worth checking out.


thanks for the heads-up

wiggle and crc have them too (mavic open pros) but out of stock...was looking at the "elite" though as i wanted ANT + and didnt really want wired (i'm assuming "wired" means there is a wire going from the hub to the head unit?)
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Re: Why power measurement is important

Postby donncha » Thu Apr 29, 2010 4:37 pm

Same here. Go to cyclepowermeters.com and remove the VAT. I've just sent them an email asking them about an Elite, so will let you know. TLL recommends them as do others over on Trannies :)
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Re: Why power measurement is important

Postby toolonglegs » Thu Apr 29, 2010 6:49 pm

If you go with cyclepowermeters.com...ring them and ask them for their best price.They always beat their web price by a fair bit.
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Re: Why power measurement is important

Postby donncha » Thu Apr 29, 2010 6:57 pm

Rang them yesterday but they're closed until Friday, so dropped them an email instead :)
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Re: Why power measurement is important

Postby JV911 » Fri Apr 30, 2010 9:02 am

thanks chaps

PowerTap Elite+ wheel £652.50 + PowerTap Front Wheel £198.00 + garmin 500 (locally bought) ~ $1560 in total

how's their postage?

toolonglegs wrote:They always beat their web price by a fair bit.


good idea - prices are a fraction more than CRC and wiggle (free postage) but if they can better their prices it would be good. They have Quarqs too ...mmm Quarq
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Re: Why power measurement is important

Postby ft_critical » Fri Apr 30, 2010 12:02 pm

Alex Simmons/RST wrote:But if you want to quantify your performance level, and work on how to improve it, then it is an excellent tool for the job.


Hi Alex, (anyone else too)

Sorry this is from the start of thread. I have a question. There is a 4km climb I do regularly. I climb that at 4watts/kg for just under10min. It is winter which is when I will work on climbing. I will be able to improve on this figure.
Secondly, I am planning on creating two other little tests - a 20min TT and a 1min sprint. The idea being that I can sustain and reach (repective to each test) a higher speed. For the tt test I would try to do it at a lower HR even though no-one much likes HR here.

Obviously, my training will seek to improve my results on these tests.

The question/comment then.... :?:

What greater benefit would I get from a power meter over the above tests (which in my humble opinion) are effectively measuring power? This is probably ignorance on how a power meter is employed during training.


Sorry you have to exlain the same things over and over.
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Re: Why power measurement is important

Postby JV911 » Fri Apr 30, 2010 12:16 pm

ft_critical wrote:This is probably ignorance on how a power meter is employed during training


i'm with you

1 - is it just a matter of initially doing a threshold test to determine your zones and then going out and riding in a particular zone?

2 - how much time is reqired analysing the data after each ride i.e 0, 5, 15, 30 mins or is just a matter of following point 1?
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Re: Why power measurement is important

Postby twizzle » Fri Apr 30, 2010 1:22 pm

JV911 wrote:
donncha wrote:Also, competitivecyclist.com in the US are doing a Comp built into a DT wheel for US$650 which might be worth checking out.


thanks for the heads-up

wiggle and crc have them too (mavic open pros) but out of stock...was looking at the "elite" though as i wanted ANT + and didnt really want wired (i'm assuming "wired" means there is a wire going from the hub to the head unit?)


Wire from the head unit to a receiver mounted on a chain or seat stay on the non-drive side near the hub.
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Re: Why power measurement is important

Postby twizzle » Fri Apr 30, 2010 1:36 pm

ft_critical wrote:What greater benefit would I get from a power meter over the above tests (which in my humble opinion) are effectively measuring power? This is probably ignorance on how a power meter is employed during training.


Sorry you have to exlain the same things over and over.


And would your speed difference be due to more power, better tyres, better position on the bike, different cadence, wind...?


I think most of the benefits are covered in this thread... you just have to get through all of the posts.
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Re: Why power measurement is important

Postby Alex Simmons/RST » Fri Apr 30, 2010 2:38 pm

ft_critical wrote:What greater benefit would I get from a power meter over the above tests (which in my humble opinion) are effectively measuring power? This is probably ignorance on how a power meter is employed during training.

Your thoughts about using a hill climb are on the right track.

But away from steep climbs, well, as twizzle alluded to, the relationship between speed and power is so dependent on a multitude of variables that speed is a pretty poor proxy for power, and hence a poor indicator of fitness.

I have ridden 4 laps of Centenntial Park (bit less than 16km) at exact same power yet times have been well over one minute different simply because of different conditions on the day. Had I relied on speed information and assumed it was an indicator of power, I would have drawn completely the wrong conclusion about my fitness.

Secondly, once you get over the initial large improvement in fitness you attain when you start training consistently for the first time (or after a long layoff), then the gains in fitness come in smaller increments. Since there is a cubic relationship between speed and power (e.g. a 2% increase in speed on the flat requires nearly an 8% increase in power), then speed is a very insensitive tool to detect any changes in fitness.

Even a 1-minute all out effort at the track can be impacted by different temperature and barometric pressure to the extent that more power might still result in a slower speed. Or the other way round.

To test for fitness without a power measurement device, you need to minimise the variables. A steep climb on a calm day is about the best option (although wind still plays a part). Hence why I wrote this item:
http://www.bikeradar.com/fitness/articl ... ting-19175

Finally, reference the following two charts showing impact on speed of both (i) temperature changes and (ii) wind on a rider on flat terrain riding at the same power with all other variables held constant. Note that a wind of 0.5 m/s is barely noticeable yet notice the big difference in rider speed that results.

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