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New Wheels and Power Meter - Review

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New Wheels and Power Meter - Review

Old 07-17-09, 12:11 PM
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New Wheels and Power Meter - Review

I purchased a set of Williams System 30 wheels with a Power Tap SL+ in the rear wheel. I mounted a set of Conti 4000s tires on the wheelset, a Dura Ace 12/25 rear cassette and mounted them on my Cervelo R3.

I have had three rides. The first was a recovery ride at the cycling gym on the rollers 8X5 95/80 cadence 115 to 120 heart rate. The second was a climb up our benchmark climb 3.2 miles in 1475 feet; 7.2% average grade. And the third was a fast paced 30 mile ride with some fast climbing, crosswinds and flatish terrain.

The wheels are much stiffer than my other wheelsets and the ride felt more lively with more road feel. The bumps were more significant although I the roads were generally very smooth. My race XXX lites – 1350 gm, Easton Ascent II - 1475 gm and the Williams 30s 1550 gm. The PowerTap SL+ power meter adds about another 100 gms to bring the total weight increase from the Bontrager Race XXX lites to 300 gm. The net effect is climbing is slower for the same power on steeper hills. However, the 30s are more aero so at some climbing speed the aero advantage will trump the weight. And most of my riding is at faster speeds so I get the aero benefit most of the time. If I want to do a hill climb race, I will use my Race XXX lites.

Descending and braking are excellent. I felt like I could let the bike go (which I did not). My lighter wheelsets seem less stable at higher speed. Not unsafe or speed wobble but they require a lot of attention. The 30s are like a rock descending. The flats were stable and seemed very good. Crosswind performance was good. However, at 170 pounds, I have enough weight so that the gusts do not blow me around as much. Lighter riders may find more aero wheels difficult to control.

I would rate the three rides very acceptable and I am getting use to the feel. It will take a few hundred miles to totally adjust to the ride / handling.

The PowerTap SL+ installed perfectly. It synched up with my Garmin 705 and worked without a hitch. I purchased the SL+ without the HR monitor or computer since I had that with my Garmin 705. Also, there are less expensive versions (one more expensive) than the on I purchased. I wanted the lighter version with larger bearings. And I could get it in all black. If I want to swap the PowerTap to my TT bike all I have to do is swap the wheels and the 705 and I have power. The PowerTap provides speed, virtual cadence and power. If you have a Garmin Speed cadence / speed sensor, the Garmin will use the cadence from the Garmin unit and the speed from the PowerTap.

It is pretty cool getting a power readout along with HR and speed. I am not going to get into my power numbers and etc. but I will say that I am surprised by the lag between breathing and HR to power increases. My power can increase a lot and my breathing and HR slowly catch up. I suggest that as anyone commences a climb, they start deep breathing right away. Do not wait until your body decides to increase breathing. It is too late. Likewise, after a climb and if there is a flat or false flat and the HR and breathing are up, the power may be down even though you feel like you are putting out a lot of effort. Effectively, you have overcooked the climb. In group rides and races, this is necessary but knowing what is happening may allow one to mitigate its effects to an extent.

Here are a couple of pics




Last edited by Hermes; 07-17-09 at 12:15 PM.
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Old 07-17-09, 12:22 PM
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Very nice! Once you start riding with power you realize as you noted that HR and breathing are lagging indicators. Watts are where it's at for sure if you want to know exactly what is going on. Combine the power data with HR and RPE and you have a much more complete picture of where you are. I'd like to have a set of those wheels. Let us know how they do if you get caught out in the rain with them.
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Old 07-17-09, 05:27 PM
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Originally Posted by BikeWNC
Very nice! Once you start riding with power you realize as you noted that HR and breathing are lagging indicators. Watts are where it's at for sure if you want to know exactly what is going on. Combine the power data with HR and RPE and you have a much more complete picture of where you are. I'd like to have a set of those wheels. Let us know how they do if you get caught out in the rain with them.
These wheels use Niobium superalloy as rim material. It is lighter and stronger than aluminum. So far, the braking is very good but not as grabby as typical aluminum rims. So braking under wet conditions is an unknown. Our rainy season is from late November to April so I will not see any rain until then. And I do not plan on taking the PowerTap out in the rain. So hopefully, I will never know the answer.

Last edited by Hermes; 07-17-09 at 08:25 PM.
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Old 07-17-09, 08:19 PM
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Gorgeous bicycle. Really, really nice. Congratulations.
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Old 07-17-09, 08:52 PM
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Your right about starting the breathing early - I noticed this last year on my morning training rides where I have to climb a couple of small hills.
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Old 07-17-09, 09:08 PM
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I think the wheels really dress up the bike. I would like to get something different, but I don't want too harsh of a ride.
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Old 07-18-09, 09:21 PM
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Originally Posted by George
I think the wheels really dress up the bike. I would like to get something different, but I don't want too harsh of a ride.
I forgot what you are riding now. IMHO, the deeper rims do dress up the bike. I suspect most of the wheelsets with deeper rims are stiffer. An approach is to go to the LBS and ask for a demo set of wheels. If they want to sell wheels, they need demo sets for just this purpose.
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Old 07-19-09, 06:58 AM
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Originally Posted by Hermes
I forgot what you are riding now. IMHO, the deeper rims do dress up the bike. I suspect most of the wheelsets with deeper rims are stiffer. An approach is to go to the LBS and ask for a demo set of wheels. If they want to sell wheels, they need demo sets for just this purpose.
I like the look of these.

https://fairwheelbikes.com/kinlin-xr2...et-p-1644.html
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Old 08-07-09, 12:06 PM
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Update...

I like the Williams wheels. After riding my Bontrager Race XXX carbons and the System 30s, I would rate the 30s slightly stiffer ride but more lateral stiffness than the XXX lites. The 30s are more stable descending. I am not ready to say the 30s are faster than my other wheels since I have not done any quantitative testing.

I rode the 30s in some very strong cross winds last night. They were not a problem but I did have to lean the bike into the wind but not more than I have had to do with other wheelsets.

Braking on the System 30s is good but not as good as aluminum. The 30s use niobium rim material that allows for the deeper rim with lighter weight. The niobium is soft and using the standard brake pads metal shards embed in the pads and make scratching sounds when applied against the rims. Williams said, this will go away with time. However, I believe that the best solution and Williams agrees is to use the Swiss Stop pads. I will give them a try this weekend.

The power meter is totally cool but not without its trials and tribulations. As an electrical engineer / finance guy, I do not mind playing around with "issues". When I got the power hub, it quit measuring power after 3 rides. I sent the wheels back to Saris and they replaced the hub (very good customer service). The new hub worked fine and then the speed was off by a factor of 2 - two times faster. Saris was clueless but would do anything I wanted. I called Garmin and after a one hour discussion with customer service and level 3 tech support from engineering, we think we have the problem fixed. The hub works fine, the 705 works fine and I am happy with the result. I think Garmin will need to revise their latest firmware in the 705.

Notwithstanding all that, the Garmin 705 with the PowerTap SL+ is a very slick high value solution once coupled with Training Peaks software. I can use the wheel on my road and TT bikes easily.

I purchased the book by Allen / Coggan "Training and Racing with Power Meter" and it is very interesting and provides IMHO, very good insight into cycling performance and how to use the power meter to get the most from it.

The information collected by the Garmin / PowerTap combination once loaded into Training Peaks offers a compelling presentation of my performance, strengths and weaknesses. I really like this information a lot and it dwarfs other software / performance data that I had been using.
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Old 08-07-09, 01:57 PM
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You must have got more money from Obama than I did.
Seriously though, I'm still think about different wheels just to try them.
I can get these cheaper than here. ($500) and I need the set for a 200#
https://fairwheelbikes.com/kinlin-xr2...et-p-1644.html
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Old 08-07-09, 01:59 PM
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Thanks for the info. The Powertap was on my list of wants last year but has fallen off since I have not even been good about using my HRM this year, nor have a really looked at much of the data my Forerunner collects. Will your coach be pooring over any of the data you are collecting and making suggestions or is that not in the contract?
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Old 08-07-09, 04:29 PM
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Originally Posted by Hermes
...However, the 30s are more aero so at some climbing speed the aero advantage will trump the weight. And most of my riding is at faster speeds so I get the aero benefit most of the time...
Hermes,
I have been wanting to ask someone about the effectiveness of "aero" wheels. Has someone quantified and compared the power requirements for various wheels and speeds in this regard? Now that you have a power meter can you do some comparisons?

Unfortunately, it seems to me it takes, at a minimum, intercalibrated power meters on all wheels sets. But still, maybe you can point us to some relevant, quantitative information?

Inquiring minds want to know.
Thanks.
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Old 08-07-09, 09:54 PM
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Originally Posted by The Smokester
Hermes,
I have been wanting to ask someone about the effectiveness of "aero" wheels. Has someone quantified and compared the power requirements for various wheels and speeds in this regard? Now that you have a power meter can you do some comparisons?

Unfortunately, it seems to me it takes, at a minimum, intercalibrated power meters on all wheels sets. But still, maybe you can point us to some relevant, quantitative information?

Inquiring minds want to know.
Thanks.
Here is some test data from a German wheel company, Xentis, using a crank based power meter at a velodrome. I have the Easton Tempest II which are similar to the Zipp 404. Note that the power savings is based on 28 mph.

Watt savings over a 32 round-spoked Ambrosio Nemesis at 45kmh/28mph
Vuelta carbon pro -38 Watt
Xentis mark 1 -37 Watt
Zipp 808 -36 Watt
Bontrager Aeolus -34 Watt
Zipp 999 -29 Watt
Ritchey carbon -28 Watt
Easton Tempest II carbon -29 Watt
Lightweight TT -27 Watt
Mavic Cosmic Carbone -22 Watt
Corima 3 spoke+Disc -20 Watt
Corima 3 spoke -20 Watt
Lightweight 12/20 -19 Watt
Corima Aero -19 Watt
Tune Olympic Gold -16 Watt
Nimble Crosswind -5 Watt

A 30 watt savings is a lot of power BUT it depends on how much you are producing at the time. 28 mph for me is about 370 watts or under 10%. Most riders cannot generate that speed very long if at all. For many group rides the guys setting tempo are riding 20ish. So if you take a pull, an aeor set of wheels may save you are few watts. Hardly enough to make a difference of feeling good taking a pull or not.

In the pack where there is turbulent air, the aero effect is minimized even more. So if you are having trouble hanging with a group, faster wheels will probably not make any difference.

Where aero wheels make sense is if you race and get in break aways. A break away for all intent and purposes is a time trial. You will spend more time riding solo at higher speeds. More aero wheels will make a difference to an extent.

Cervelo has a good discussion on aerodynamics on their website. HED has some very good interactive graphs on aero drag coefficients for their wheels as well as competitors.

The real beauty of the power meter is that it shows how much power you make. I realized how much I was short in some areas and how much I have improved in a short period of time. IMHO, this is where the action is for improving performance. Hundreds of watts are on the table to be picked up versus a few by better wheels and bicycles.
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Old 08-08-09, 04:27 AM
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Originally Posted by Hermes
\The real beauty of the power meter is that it shows how much power you make. I realized how much I was short in some areas and how much I have improved in a short period of time. IMHO, this is where the action is for improving performance. Hundreds of watts are on the table to be picked up versus a few by better wheels and bicycles.
+1 It's the engine - not the equipmemt.

A while back -I think you stated you felt aero wheels were better for climbing, I was not so concerned about it because of the lower speeds involved, have you changed your thinking or do you still believe this is the case? I may have completely missunderstood your point.

I assume you are both looking at how to make better use of the watts you are putting out as well as how to make the engine put out more watts over time. I would be interested in hearing what you are finding and how the PM has helped you determine that. I am relying on you to build up my mental case for putting one of these little gizmo's back on my christmas list...
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Old 08-08-09, 06:46 AM
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The deeper dish wheels do make a difference when riding fast even if you are not "off the front". I have been using my Williams Carbon 58's for the past month in races and I can tell a difference even though I don't have a PT. These image links show me racing and going through a 40 mph turn. The downhill continued onto a slight downhill flat and the field would split up some on the crit's decent. We would then be riding in single file for about 1/4 mile, while the riders would frantically work to get back in the leaders draft, before we started back up the hill for the next lap. I loved the wheels on the decent and during the "catch up". The 1.3 mile course was basically 2/3rds downhill, with 4 turns, then back up hill to do it again. My son purchased the same wheels as Herme's has last year and had zero issues with them and is planning to use them during cross season this year. This past spring we both purchased the 58's and got a "small group discount". Even if the wheels didn't help make me faster the "cool factor" from the look and, even more so from, the sound the wheels and bike makes when riding and shifting are worth every cent to this old racing dinosaur.

https://www.photoreflect.com/pr3/orde...5E010019&po=19

https://www.photoreflect.com/pr3/orde...5E010054&po=54
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Old 08-08-09, 08:43 AM
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Originally Posted by Allegheny Jet
The deeper dish wheels do make a difference when riding fast even if you are not "off the front". I have been using my Williams Carbon 58's for the past month in races and I can tell a difference even though I don't have a PT. These image links show me racing and going through a 40 mph turn. The downhill continued onto a slight downhill flat and the field would split up some on the crit's decent. We would then be riding in single file for about 1/4 mile, while the riders would frantically work to get back in the leaders draft, before we started back up the hill for the next lap. I loved the wheels on the decent and during the "catch up". The 1.3 mile course was basically 2/3rds downhill, with 4 turns, then back up hill to do it again. My son purchased the same wheels as Herme's has last year and had zero issues with them and is planning to use them during cross season this year. This past spring we both purchased the 58's and got a "small group discount". Even if the wheels didn't help make me faster the "cool factor" from the look and, even more so from, the sound the wheels and bike makes when riding and shifting are worth every cent to this old racing dinosaur.

https://www.photoreflect.com/pr3/orde...5E010019&po=19

https://www.photoreflect.com/pr3/orde...5E010054&po=54
+1 Great point on bridging during a race and the advantage of aero wheels.
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Old 08-08-09, 02:41 PM
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Originally Posted by cyclinfool
+1 It's the engine - not the equipmemt.

A while back -I think you stated you felt aero wheels were better for climbing, I was not so concerned about it because of the lower speeds involved, have you changed your thinking or do you still believe this is the case? I may have completely missunderstood your point.

I assume you are both looking at how to make better use of the watts you are putting out as well as how to make the engine put out more watts over time. I would be interested in hearing what you are finding and how the PM has helped you determine that. I am relying on you to build up my mental case for putting one of these little gizmo's back on my christmas list...
When the wider rim wheels first appeared they were much heavier. As I remember, Cervelo and possibly Zipp had a chart of grade versus speed when the aero wheel's reduced drag required less power for the same speed as the KOM wheelset counterpart. The typical break point for the P/1/2 is 8% and the rest of us 5 to 6%. I cannot find the reference any longer. If you are really slow climbing then a KOM wheelset is the only solution.

These wheels are now much lighter. Our Easton Tempest IIs 50 mm carbons are 1250 gm for the tubular set. These wheels are more aero and just lighter and faster.

As a point, I have not been in a road race, TT, crit, or track race where I have not had a set of race wheels optimized for the event.

I wanted a training set of wheels that were not carbon, aero and light. The System 30s have a deep rim for an alloy wheel with a competitive weight and I could have a PowerTap hub. My point was that the System 30s were technically more aero (less spokes on the front wheel with a deeper rim) than my Bontrager Race xxx lite carbons. I feel that at some point climbing, the added aero advantage will offset the heavier weight. It is not possible to quantify, test or prove my hypo. And Williams is a sponsor so we get a very good deal on the wheelset.

With respect to the power meter, I suggest purchasing the Allen / Coggan book. You will have no problem (as I recall, you do math / science work) reading the book and figuring out if a PM is right for you. And they discuss the various types of power meters strengths and weaknesses. Learning to use the power meter, software and interpretation of the information is on par with learning to use an electronic spreadsheet with complicated formulas embedded in the software.

The key difference between power and heart rate is that you need to test yourself to determine and input the most relevant metric which is threshold power. There is no easy way to get this number other than do what they say to do in the book. Hill intervals may seem like an upside to testing yourself for threshold power. Once you input your threshold power into Training Peaks software, it calculates your power zones. After each ride, it calculates your Total Stress Score, Normalized Power and Intensity plus a myriad of other metrics relevant to the ride and your weekly averages. You test yourself monthly to see if the threshold power is changing. If it increases, you input a new number into the software and all the power training zones are increased.

So this is where the rubber meets the road...it is a very expensive instrument that makes you work even harder than you have ever done before. You either like that or you do not. If you want to work very hard and build the engine, this is the way to do it. Couple a PM and a coach together and you have a perfect communication link. The coach prescribes the workout and the athlete executes. The coach reviews the results and it is discussed and new targets set.

Last edited by Hermes; 08-08-09 at 02:45 PM.
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Old 08-08-09, 03:08 PM
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Thanks Hermes - I will get teh book.
Yes - I am also an EE - and still practice same in a research lab, good data and the theory to process it is the key to making anything better. I will get the book.
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Old 08-08-09, 03:09 PM
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Hermes,
Thanks for the data. Is it know what the main contribution to wheel aerodrag is? Is it the rim profile (for a given width) or the spokes?

Also, do these number scale with speed as v^2?
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Old 08-08-09, 04:30 PM
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Originally Posted by cyclinfool
Thanks Hermes - I will get teh book.
Yes - I am also an EE - and still practice same in a research lab, good data and the theory to process it is the key to making anything better. I will get the book.
Perfect...once you read the book, you will understand power meters. We can certainly revisit the discussion.
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Old 08-08-09, 05:00 PM
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Originally Posted by The Smokester
Hermes,
Thanks for the data. Is it know what the main contribution to wheel aerodrag is? Is it the rim profile (for a given width) or the spokes?

Also, do these number scale with speed as v^2?
This is where I am a smart dumb guy i.e. smart enough to speculate with some certainty.

Look at it from boundary conditions to understand the physics. The perfect wheel is a disc. There are no spokes and the surface is designed for "good" airflow across its surface at various wind angles. The other extreme is a band with spokes connected to a hub. The spokes act like an poor airplane propellor and create drag as they spin. Move the wheel through the air horizontally and the air will hit the spinning spokes producing more drag. Now, let's consider a 50/50 spoke disc combination. Less propellor drag better air flow.

So wheel manufacturers like Zipp make different depth rims to optimize the aero drag at different wind angles and use less spokes to reduce propellor effect and drag. At indoor track racing, pursuit riders use a front and rear disk. If you have too much rim depth, cross winds will render the bike not rideable.

The formula for drag is related to moving a volume of air out of the way. The equation is a cubic function V^3. That is why it takes a lot of power to go just a little faster as speeds begin to increase.
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Old 08-08-09, 08:18 PM
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Great discussion. Well at least if you are an EE! Beginning to remind me of dynamics classes......

I saw or read something where it talked about companies now looking at the point of rotation of the wheel-ie, the upper front half of the wheel and it being a critical part of "knifing" through the air. It helped to support the idea of deeper dish rims reducing drag.

For the type of riding I do, I still lean towards overall weight for most of my riding as there are some the mid range hills. I don't seem to have an issue hanging with groups or accelerating and closing gaps on relatively flat roads but I'm a terribly slow climber and really have to work my tail off to keep up on hills. It doesn't help when you have tooth picks for legs!!

I do have special wheels for the few TT's I do and have enough data to show where they reduced my times by about 4% over 10 miles on a relatively flat course. That is huge!
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