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Weight savings more important on the front wheel or rear wheel?

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Weight savings more important on the front wheel or rear wheel?

Old 07-27-11, 12:30 PM
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Weight savings more important on the front wheel or rear wheel?

I just bought a Kinlin XR-200 that claims 390grams for my rear wheel and a Kinlin XR-300 that claims 460 grams for my front wheel.

Does it make sense to go with a lighter wheel in the back where you're applying your power?

Edit: To clarify, does it make sense with regard to speed and "moment of inertia" to put a lighter wheel on the back then the front.

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Old 07-27-11, 12:40 PM
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Those are rims - not wheels and the selection of front to rear has less to do with weight than it does with spoke drilling options and ultimately depth. You want the deeper rim in the rear. The only reason to even go with a XR200 rim in the front would be to save overall weight on the set.

In a wheelset approx 60-70% of the rider weight is carried on the rear wheel. Put that XR200 rim on the rear and see what happens.
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Old 07-27-11, 12:51 PM
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Originally Posted by Psimet2001 View Post
Put that XR200 rim on the rear and see what happens.
And this is a quote from your website: "XR-200 19mm deep. Ultralight alloy rim. This rim is THE choice when you are building up a light race or climbing set. I have seen rider weight limits in the 190 range."
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Old 07-27-11, 01:32 PM
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Originally Posted by BikeNube View Post
And this is a quote from your website: "XR-200 19mm deep. Ultralight alloy rim. This rim is THE choice when you are building up a light race or climbing set. I have seen rider weight limits in the 190 range."
Nice that you only quote the first part...here is the rest of it:

Originally Posted by my site
XR-200 19mm deep. Ultralight alloy rim. This rim is THE choice when you are building up a light race or climbing set. I have seen rider weight limits in the 190 range. On the surface I would agree with that, but its light weight is impressive and should only be used in the proper application.
I'm going to take a wild guess that you are more towards 190 than 120. I didn't say that I say it has a 190 limit. I say that I have seen (others) who list it at 190. I do not. I don't put weight limits on anything. Stupid to put a straight weight limit on only a rim. It would depend on the number, lacing and type of spokes used.
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Old 07-27-11, 01:41 PM
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Originally Posted by Psimet2001 View Post
Nice that you only quote the first part...here is the rest of it:



I'm going to take a wild guess that you are more towards 190 than 120. I didn't say that I say it has a 190 limit. I say that I have seen (others) who list it at 190. I do not. I don't put weight limits on anything. Stupid to put a straight weight limit on only a rim. It would depend on the number, lacing and type of spokes used.
Nope. Weigh between 144-148 lbs depending on hydration. Why would more towards 190 be your guess? Also, you're now saying other things are important than just the rim as opposed to what you first said about not being able to put a xr200 at all on the back??

I'm sorry for nitpicking -- I'm just trying to make sure I didn't just pick out a rim combo that's gonna fall apart on a training ride.

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Old 07-27-11, 02:00 PM
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Originally Posted by Psimet2001 View Post
Stupid to put a straight weight limit on only a rim. It would depend on the number, lacing and type of spokes used.
+1

also add the rubber you are using (tubular or clincher)

aside from any differences in 'handling' which might be affected by the wheel build, spinning up the wheels is a 'pair' thing.
Unless you are wheelie-ing, you accelerate both wheels. so even though traction is depend where the force is laid down, the effort to overcome current inertia is determined by the state of both wheels. Switching any component from one wheel to the other should have no overall effect on acceleration. Light rubber/rim up front and heavy in back, or vice versa, is a wash (traction considerations aside).
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Old 07-27-11, 02:02 PM
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I wouldnt think weight front or rear would matter since both wheels are usually connected and rotate together as one system.
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Old 07-27-11, 02:33 PM
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what drillings did you get these rims in?
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Old 07-27-11, 03:22 PM
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Originally Posted by pdedes View Post
what drillings did you get these rims in?
20/24
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Old 07-27-11, 03:29 PM
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I have XR200's in 24/28 for what it's worth, and the wheels are still only 1160 grams.
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Old 07-27-11, 05:05 PM
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Originally Posted by BikeNube View Post
Nope. Weigh between 144-148 lbs depending on hydration. Why would more towards 190 be your guess? Also, you're now saying other things are important than just the rim as opposed to what you first said about not being able to put a xr200 at all on the back??

I'm sorry for nitpicking -- I'm just trying to make sure I didn't just pick out a rim combo that's gonna fall apart on a training ride.
Sorry - lost on what you're confused on. Spoke count makes a huge difference but not as much as the rim you begin with does. You said you have an XR200 and a 300. Why in the world would you ever consider putting the 200 in the rear in that combination? Makes no sense. The rear carries most of the weight and outside of spoke count another large factor can be rim depth. The area moment of inertia increases as the rim depth increases. Think "I-beam" versus solid beam.

So what's your specific question? Maybe you don't have one and are simply wanting to discuss theory? No telling. But if I had a 200 and a 300 rim to make a set out of the 200 would be in the front as it is the weaker rim. Period.

As for my feelings on XR200 - You quoted my site. It says what I think. I don't like to directly "attack" other wheel builders, but my experience has been that too many think that the XR200 is an acceptable rim for daily riding. I personally have seen a 125 male rider destroy 2 within a year using them on a powertap. He bought the wheel from elsewhere - another internet builder - and had them replace the rim each time. Eventually he had me replace it with a 270. A couple of years later he is still riding it with no issues.

So.....I guess I don't sit and debate theory. I just go off of direct real world experience. I don't recommend the 200 for anyone as a daily rider. If the customer insists then I put a 270 on the rear and leave the 200 for the front because the rear carries most of the weight. When making an uber light weight climbing set for specific events then yes the 200 front and rear can work just fine and I have used them. Sold a set to someone on here just last week that came in at something like 1260.

Again - my philosophy - but a handful of grams doesn't change your ride, but at some point constantly trying to shed them can lead to some poor decisions that can directly affect your ride by leaving you stranded.
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Old 07-27-11, 05:06 PM
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To touch on the spoke count thing - if someone came to me at 170 and wanted an uber climbing set and wanted 200's I would overspoke them and x the lacings to give them as much durability as I could
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Old 07-27-11, 05:17 PM
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Originally Posted by BikeNube View Post
20/24
You might actually want to consider putting the 20h XR-300 on the rear, but I would not have even considered the combination you chose. I remember a long time ago getting a deal on some NOS GEL280 and GL330 rims, and some old guy telling me to put the 280 on the rear for acceleration. It didn't make sense then and it doesn't make sense now. You generally want the stronger rim (weight aside) on the rear.
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Old 07-27-11, 05:47 PM
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Well the 300 is a tab bit narrower and the aero profile does the most benefit up front since it's hitting the air first.

But this is way off topic, my first post says nothing about weight or aerodynamics. As my first post asks, does moment of inertia apply to both wheels and not just the rear where you're applying your power?
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Old 07-27-11, 06:56 PM
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So you want to debate theory with no regard to what you will actually use? Regardless - you don't get energy for free. You have to "accelerate" both wheels. Sorry. They don't start spinning for free or on their own.
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Old 07-27-11, 07:04 PM
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I though the aerodynamics involved with rims of this height are minimal anyways. I thought you had be over 38mm or 40mm to even see any advantage.
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Old 07-27-11, 07:33 PM
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Originally Posted by BikeNube View Post
Well the 300 is a tab bit narrower and the aero profile does the most benefit up front since it's hitting the air first.

But this is way off topic, my first post says nothing about weight or aerodynamics. As my first post asks, does moment of inertia apply to both wheels and not just the rear where you're applying your power?
1) The aero benefit of a rear wheel has been determined to be about 75% of the front, so it's not a big difference.
2) I believe we already answered that question. It applies to both wheels, so it doesn't matter where the weight is.


Originally Posted by save10 View Post
I though the aerodynamics involved with rims of this height are minimal anyways. I thought you had be over 38mm or 40mm to even see any advantage.
Another myth created by people who want a line drawn instead of recognizing progressive results. All else equal (which it rarely is), 30mm is more aero than 20, 40 is more aero than 30, and so on.
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Old 07-27-11, 08:27 PM
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Originally Posted by urbanknight View Post
1) The aero benefit of a rear wheel has been determined to be about 75% of the front, so it's not a big difference.
2) I believe we already answered that question. It applies to both wheels, so it doesn't matter where the weight is.


Another myth created by people who want a line drawn instead of recognizing progressive results. All else equal (which it rarely is), 30mm is more aero than 20, 40 is more aero than 30, and so on.
Yes but to put the weaker rim on back to get a "aero" benefit from the 300 is silly.
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Old 07-27-11, 08:36 PM
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Originally Posted by save10 View Post
I though the aerodynamics involved with rims of this height are minimal anyways. I thought you had be over 38mm or 40mm to even see any advantage.
My understanding is that the weight penalty you take isn't offset by aerodynamic advantage in this range of depths. The aero gains will doubtless increase as the rim gets deeper but the extra weight means the gains are effectively cancelled out, and there is a leap in terms of watts saved at around 40mm. Which explains why there is a cluster of wheels that depth in the marketplace.
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Old 07-27-11, 08:53 PM
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Originally Posted by jsutkeepspining View Post
Yes but to put the weaker rim on back to get a "aero" benefit from the 300 is silly.
Precisely
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Old 07-27-11, 09:04 PM
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For reference, I don't think you could ever find a wheel set build (like the one you have planned) being ridden in a pro event. You are really going against all conventional wisdom with this planned build.
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Old 07-27-11, 09:07 PM
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Originally Posted by GDA View Post
For reference, I don't think you could ever find a wheel set build (like the one you have planned) being ridden in a pro event. You are really going against all conventional wisdom with this planned build.
hey its bf and the 41, stupidity is normal.
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Old 07-27-11, 09:18 PM
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Originally Posted by jsutkeepspining View Post
hey its bf and the 41, stupidity is normal.
Well then.... Long live the king!
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Old 07-28-11, 08:12 AM
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Originally Posted by Minion1 View Post
My understanding is that the weight penalty you take isn't offset by aerodynamic advantage in this range of depths. The aero gains will doubtless increase as the rim gets deeper but the extra weight means the gains are effectively cancelled out, and there is a leap in terms of watts saved at around 40mm. Which explains why there is a cluster of wheels that depth in the marketplace.
This is hogwash. Rim shape has more to do with rim shape than rim depth.

As for the OP's core question, you have to accelerate both wheels so the weight from both rims is going to count equally... unless of course you plan to be able to power-slide your rear end. Back wheels are typically so much weaker than fronts because the bracing angle is limited by the cassette. Given a choice, you should always put your stronger rim in the rear. Of course, with you getting the 200 in 20h and the 300 in 24h, it's probably a bit of a wash. Psimet could advise further. You're fairly lightweight though and if you're smooth then it shouldn't matter much.

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Old 07-28-11, 10:14 AM
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Thermodynamics....

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*this message brought to you by the committee for spreading the concept of conservation of energy through the basic laws of Thermodynamics - here at the CSCCETBLT we like to say, "You can't win, You can't break even, You can't even really know where you are."
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