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I think that's what the modern world calls 'Calculus' ;-)

Posted by: Mirror|rorriM on 2002-11-15 22:16:30
Account #: 11167

In Reply to: A little flawed on rotational inertia. You have to chop the wheel in a thin pizza slice... posted by Audiboy on 2002-11-15 15:24:12

You don't need to integrate anything is you assume that 1) the radius is constant, and 2) the density is constant.

Like I posted below, Toy_Guy's post is giving an absolute best case scenario. Realistically, the keyboard tuners are even further off than his post indicates. Hugely so.

Mirror|rorriM
I've ridden a total of 52 days so far this season
I got to snowboard a total of 45 days in the 06-07 season.
I got to snowboard a total of 58 days in the 05-06 season.
I got to snowboard a total of 139 days in the 04-05 season.
RYAN SMITH ("GOLFRSI" or "BIADesigns") STOLE MY A-PILLAR. DON'T DO BUSINESS WITH THIS FRAUD

RYAN SMITH ("GOLFRSI" or "BIADesigns") STOLE MY A-PILLAR. DON'T DO BUSINESS WITH THIS FRAUD

My First Post

Thread:

A study investigating the effective inertial weight of wheels. Warning: technical in nature. - Toy_Guy 2002-11-15 12:38:48 (8165 views)

Craig 0wnz j000!! - Xr8edS4 2002-11-16 08:09:26 (930 views)

I just edited my post to add some clarification. - Toy_Guy 2002-11-16 06:04:34 (824 views)

you know what's funny - frank 2002-11-15 16:52:31 (1069 views)

The only variable with a wheel is the weight (within a given size) - this is not the case with tires - Mirror|rorriM 2002-11-15 22:20:29 (990 views)

Actually - squidix9 2002-11-16 21:43:13 (1558 views)

Those look mean ; ) - Singletrack 2002-11-17 16:25:40 (799 views)

That's what - squidix9 2002-11-18 05:37:05 (648 views)

That's a cool site, couldn't find the video though. - Singletrack 2002-11-18 07:17:19 (636 views)

Rat's - squidix9 2002-11-19 06:04:46 (608 views)

Yeah I saw the pics - totally nuts. How did you get into ice racing? - Singletrack 2002-11-19 06:59:43 (685 views)

I got into ice racing because - squidix9 2002-11-19 13:18:56 (725 views)

Very cool man, thanks for all the info : ) - Singletrack 2002-11-19 14:35:36 (489 views)

Other than being F*&^&!g cold winter is cool for racing - squidix9 2002-11-19 20:12:02 (542 views)

I looked into this. Toyo TS-1 is the lightest in a given size. Bridgestone S0-3 is real heavy. - PhoenixS4 2002-11-15 17:08:59 (1676 views)

And don;t forget, a 235 is about a pound heavier than a 225. - PhoenixS4 2002-11-15 17:39:23 (614 views)

but - BSOD 2002-11-15 17:07:09 (652 views)

Good point. I speced out my winter vs summer weight about a month ago and - Singletrack 2002-11-15 17:00:48 (776 views)

werd, and tires are cheaper than bling bling rims - frank 2002-11-15 17:02:27 (1233 views)

unless you're sensible... OZ SL's are light and well priced. - S4 from GT 2002-11-16 01:22:13 (926 views)

A little flawed on rotational inertia. You have to chop the wheel in a thin pizza slice... - Audiboy 2002-11-15 15:24:12 (1242 views)

I think that's what the modern world calls 'Calculus' ;-) - Mirror|rorriM 2002-11-15 22:16:30 (689 views)

woah...old man of the internet...aim# 9!?! and I though I;d been here a while - SwampGTI 2002-11-15 17:04:20 (697 views)

oops, nevermind, I just read George reply. - Audiboy 2002-11-15 15:26:39 (664 views)

Nice analysis ... - sj6spslvrS4sdn 2002-11-15 15:12:22 (635 views)

Sounds about right to me. I have always gone by 1lb unsprung equals around 3 times sprung. - Singletrack 2002-11-15 14:08:09 (605 views)

Is this in Engrish? - Ben AKA NUHuskyfan 2002-11-15 14:02:20 (575 views)

Don't forget the Moment of Inertia for the Brake rotors, etc... ;) - reefer_bob 2002-11-15 13:58:37 (793 views)

I think saving 16 lbs. on brake rotors felt like it saved me 19.2 lbs. based on this... - LCP 2002-11-15 15:34:14 (715 views)

I run - squidix9 2002-11-15 13:50:04 (732 views)

What size is the OZ forged wheel and what does it look like? - PhoenixS4 2002-11-15 14:08:55 (1075 views)

I've got a bunch of 15X7's and 15X8's - squidix9 2002-11-15 21:23:46 (971 views)

The analysis is valid for no loss of traction. A burnout has different dynamics. - Toy_Guy 2002-11-15 13:59:20 (562 views)

True, but my point is the ability to - squidix9 2002-11-15 21:19:23 (623 views)

OK!!! All fixed up with the sub/superscripts added in. - Toy_Guy 2002-11-15 13:44:17 (735 views)

You're a swell guy. =) - LCP 2002-11-15 15:21:38 (616 views)

I would stress in the beginning its a 10 lb reduction PER wheel/tire just to clarify - Stealth4 2002-11-15 13:34:39 (614 views)

So ultralight tires is where the smart money's at!! - RichmondS4 2002-11-15 13:28:41 (764 views)

so my effective weight loss, if i bought lighter wheels, doesn't justify my effective wallet burn. - Mr. Piggie(mike01s4) 2002-11-15 13:12:22 (808 views)

...and that's why manufacturers don't do it either... - LCP 2002-11-15 13:14:57 (820 views)

No - making the wheels *heavier* can aid fuel economy - Mirror|rorriM 2002-11-15 14:10:04 (759 views)

I think that's a stretch - stiles_s 2002-11-15 14:48:35 (637 views)

I know it's a stretch...it really depends on what the EPA uses for their test - Mirror|rorriM 2002-11-15 15:02:10 (557 views)

for mfg'ers, cost of a heavy/stong wheel << cost of a light/strong wheel - BSOD 2002-11-15 13:45:48 (718 views)

Please edit your post to include subscripts. It's permitted HTML. See Forum FAQ. - LCP 2002-11-15 12:56:39 (551 views)

why dont you do it :) - Stealth4 2002-11-15 13:15:25 (679 views)

Toy Guy did enough as it is! - Mr. Piggie(mike01s4) 2002-11-15 13:09:43 (629 views)

Thats close, but not quite right... - George @ BostonAudi 2002-11-15 12:55:16 (1001 views)

By pretending the mass was all at the radius of the wheel/tire, he gave the best case scenario - Mirror|rorriM 2002-11-15 14:05:19 (666 views)

Exactly, Jeff. I'm glad you follow the simple physics! - Toy_Guy 2002-11-15 14:15:39 (533 views)

I think the internet tuning business would die if we started scanning the books on our shelves :-) - Mirror|rorriM 2002-11-15 14:17:38 (531 views)

George, why don't you try reading my post in entirety before commenting? - Toy_Guy 2002-11-15 13:45:37 (620 views)

I read the entire post. Twice now... - George @ BostonAudi 2002-11-15 13:59:03 (724 views)

It's sound. - Mirror|rorriM 2002-11-15 14:16:11 (710 views)

Agree. I was thinking of acceleration and braking, not constant velocity when I posted above. - Audiboy 2002-11-15 15:33:13 (576 views)

The same math applies, regardless of acceleration - Mirror|rorriM 2002-11-15 22:22:48 (547 views)

Well, I'll back out in disagreement... - George @ BostonAudi 2002-11-15 14:29:56 (635 views)

Sorry, my terminology was misleading - Mirror|rorriM 2002-11-15 14:40:29 (598 views)

"how the car is driven" == AWD vs 2WD, not driver skill :) - George @ BostonAudi 2002-11-15 14:00:59 (1018 views)

That only affects dyno numbers, not the actual #s put down on the pavement - Mirror|rorriM 2002-11-15 14:11:18 (596 views)

george, he's calculating it as if all the weight was all the way - BiTurboBoy 2002-11-15 13:02:39 (762 views)

Right... I've always seen approx 4x equivalence... - George @ BostonAudi 2002-11-15 13:04:43 (772 views)

damn, engineering is hard to read without subscripts.... - BiTurboBoy 2002-11-15 12:45:02 (679 views)

You could be totally wrong and I would have no clue, but it sounds good =) - 2k2S4 2002-11-15 12:41:09 (548 views)

I read it on the internet.... ;-) - Mirror|rorriM 2002-11-15 14:18:17 (565 views)

It's not wrong, trust me :-) - Toy_Guy 2002-11-15 12:43:49 (631 views)

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