Easy & cheap way to lose 4.73 lb of peripheral rotating weight - Yamaha R3 Forum
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post #1 of 9 Old 02-01-2018, 01:58 PM Thread Starter
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Easy & cheap way to lose 4.73 lb of peripheral rotating weight

Anyone who's serious about motorcycles knows that lighter weight makes a bike handle better. In addition, any weight reduction in a rotating part within the drivetrain adds to that basic weight saving dramatically by:

- Either reducing the power required to accelerate the bike (because the bike becomes lighter), OR increasing the rate of acceleration without modifying the engine's power (because less of the NET engine power is diverted to spinning up rotating driveline components and can instead accelerate the bike a bit faster.

However, reducing bike weight is generally very costly when measured on a dollars spent per pound of weight reduction basis!

Some typical examples on the R3 include (note cANADIAN prices, including taxes. U.S.prices are a bit better deal):

- Lithium battery versus stock lead acid battery:$225/4.2 lb = $54 / lb (This assumes using the Shorai lithium battery that Shorai recommends for street use, not the little bit lighter and less costly one used by racers for technical reasons)

- Typical full exhaust: $910 to $1140 / 6 to 11 lb = $83 to $190 / lb (CHECK the ACTUAL weight reductions, not the erroneous ones posted in way too many ads)

- Rear seat cowl versus stock rear seat: $180/1.45 lb = $124 / lb (The genuine Yamaha cowl is very costly, but the eBay ones are junk)

- Good rearsets $500 / 1 lb = $500 / lb (Rearsets are costly AND the weights of the stock footpeg assemblies are light enough to begin with that big reductions just aren't physically possible)

There are of course some exceptions that are "free", like removing passenger footpegs and even the left passenger footpeg support, or removing the crappy toolkit, but most weight reductions are expensive.

So, it is GREAT when you find a weight reduction that

Anyone who's serious about motorcycles knows that lighter weight makes a bike handle better. In addition, any weight reduction in a rotating part within the drivetrain adds to that basic weight saving dramatically by:

- Either reducing the power required to accelerate the bike (because the bike becomes lighter), OR increasing the rate of acceleration without modifying the engine's power (because less of the NET engine power is diverted to spinning up rotating driveline components and can instead accelerate the bike a bit faster.

However, reducing bike weight is generally very costly when measured on a dollars spent per pound of weight reduction basis!

Some typical examples on the R3 include (note CANADIAN prices, including taxes. U.S.prices are a bit better deal):

- Lithium battery versus stock lead acid battery:$225/4.2 lb = $54 / lb (This assumes using the Shorai lithium battery that Shorai recommends for street use, not the little bit lighter and less costly one used by racers for technical reasons)

- Typical full exhaust: $910 to $1140 / 6 to 11 lb = $83 to $190 / lb (CHECK the ACTUAL weight reductions, not the erroneous ones posted in way too many ads)

- Rear seat cowl versus stock rear seat: $180/1.45 lb = $124 / lb (The genuine Yamaha cowl is very costly, but the eBay ones are junk)

- Good rearsets $500 / 1 lb = $500 / lb (Rearsets are costly AND the weights of the stock footpeg assemblies are light enough to begin with that big reductions just aren't physically possible)

There are of course some exceptions that are "free", like removing passenger footpegs and even the left passenger footpeg support, or removing the crappy toolkit, but most weight reductions are expensive.

So, it is GREAT when you find a weight reduction that is not horribly expensive to begin with,but if done at the right time, can actually be essentially "free".

I'm talking about changing the tires you use on your R3, and preferably doing it when your current tires are worn out and you need to buy new tires ANYWAY.

Most people would be surprised to find the magnitude of the change, and most people fail to consider that the weight reduction achieved by tire changes is TRIPLY valuable because:

- The reduction in weight first of all lowers the weight of the bike as a whole

- But, the tires are also rotating, and they are THE MOST PERIPHERAL COMPONENT OF THE ENTIRE REAR WHEEL ASSEMBLY, so when you reduce their weight you have an immense effect on the wheel's moment of inertia, which has a dramatically beneficial effect on the (a) nimbleness and (b) handling of the bike. It is also noteworthy that the tires are in almost all cases the single heaviest individual component of a wheel, and their outermost peripheral location magnifies their impact tremendously compared to reducing the weight of other wheel components like brake rotors or sprockets

- And, since the tires must be accelerated rotationally as well as linearly when accelerating the bike, the reduced moment of inertia of a lighter tire again magnifies all other benefits even more.

The R3 is a particularly attractive target on which to reduce tire weight, because the stock Michelin Pilot Street tires, as well as being bias ply versus radial, are also very heavy:

The rear Michelin Pilot Street 140/70-17 is hard to find a weight for online, even on the Michelin website (Michelin must be reluctant to confess its high weight), but 2 different sources indicate it weighs at least 13.75lb. To put that high weight into perspective, the Pirelli Diablo 240/40ZR-18 rear tire on my last Harley, a tire that is 9-1/2 inches wide!, weighed just 16.0 lb.

The front Michelin Pilot Street 110/70-17 is even harder to find a weight for, but at least one source says it weighs 8.8 lb.

So, the total weight, rear + front, = 22.55 lb

The day I bought my R3 a few days ago, I ordered a pair of much lighter tires: Bridgestone Battlax BT-090 Tires.

The specs for these claim 10.20 lb rear, 7.9 lb front.

But the actual weights on the tires I received yesterday are 10.14 rear, and 7.68 front.

So, my new total tire weight rear + front = 17.82 lb

This is an astonishing 4.73 lb weight reduction juist by changing the tires!

Can you imagine how much acceleration, handling, and nimbleness effect this large a weight reduction will have on an R3 that only weighed 366 lb stock in total with a full tank of gas?

Note that the tires I actually recieved weigh less than the nominal specs. A tire weight variation from spec is not unusual, because of the way that manufacturers make tires. But unfortunately, the variation can be in EITHER direction - down or UP.

So, when shopping for tires, try to visit a dealership that has a LARGE inventory of the tire you want, so that you can bring an ACCURATE digital postal scale with you (not a typical bathroom scale!) and weigh a few and pick the lightest.

If this is not possible given your location and available dealerships, at least LOOK at the spec weights and, ALL SAFETY AND HANDLING AND DURABILITY VERSUS SENSITIVITY CONSIDERATIONS BEING EQUAL, go with a brand and model that has lower weights versus higher weights, unless you really, really want unsophisticated tires that will last a huge number of miles but feel like wood. There ARE people, mostly long range tourers or commuters, who want long tread life and don't care about the tire feeling wooden because their entire bike feels wooden because it weighs so much! But, this being an R3 "sportbike" site, I suspect we have very few of those folks here.

And no, I am not suggesting that you go out and buy lightweight tires when your current tires still have good tread, nor am I suggesting that you disregard other factors important to you besides tire weight. But, if all other factors on 2 different sets of tires are reasonably equal, why would you pick the heavier ones? ASK what the tires weigh.

By the way, my stock Michelin Pilot Street tires will be removed from the bike tomorrow, and have just 29 kilometers on them. If there is a Canadian reading this posting, shoot me a PM with a reasonable offer for them. No American or other foreign buyers, as the shipping costs and cross-border hassles just don't make sense for either seller or buyer!

Jim G
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post #2 of 9 Old 02-01-2018, 05:59 PM
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Will weigh your stock Michelin street pilot tires when removed? I find that the weights mentioned for those tires in this thread seem to be high at 8.8 lbs and 13.75 lbs. I changed out the OEM tires last month, but I do not have any way to make an accurate weight measurement other than a sloppy bathroom scale. Already gave the rear away, but I think I might have the front somewhere laying around, I will check it on the bathroom scale if I can find it.
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post #3 of 9 Old 02-01-2018, 06:06 PM Thread Starter
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Originally Posted by kiko View Post
Will weigh your stock Michelin street pilot tires when removed? I find that the weights mentioned for those tires in this thread seem to be high at 8.8 lbs and 13.75 lbs. I changed out the OEM tires last month, but I do not have any way to make an accurate weight measurement other than a sloppy bathroom scale. Already gave the rear away, but I think I might have the front somewhere laying around, I will check it on the bathroom scale if I can find it.
Don;t waste your time using a bathroom scale on the tires. A bathroom scale's accuracy is very poor even when used for readings in its "normal" range (people's weight range), and ususable for weights as low as these tires.

I have a high precision scale that I weigh all my parts on, and yes, I will be weighing the michelin take-offs after the tire changeover, as produciton tire weights vary by a huge amount. I recall that one time when I was buying tires (I forget the brand and model), the weight variance across 3 "identical" tires was close to 2 lbs, although it's usually less than that!!

Of course a tire also loses weight as it wears out its tread, and I wonder if a tire's weight changes at all in use or with age (like framing lumber does ).

By the way, on that Harley I mentioned where the 240 size tire weighed 16 lb: The stock Dunlop on that bike weighed 22.5 lb!! When I changed to the Pirelli, it honestly felt like the bike had lost a pair of concrete overshoes.

Jim G
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post #4 of 9 Old 02-01-2018, 06:18 PM
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I agree the bath scale is somewhat lacking in precision. I found the used front OEM tire and was really surprised that it did weigh on the digital scale at 8 lbs. Had about 10,000 miles on it. I would have guessed more like 7 lbs by the feel of the tire in my hand. I weighed myself then took a second weighing with the tire in hand. Tire alone on the scale never registered.
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post #5 of 9 Old 02-01-2018, 06:59 PM Thread Starter
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Originally Posted by kiko View Post
I agree the bath scale is somewhat lacking in precision. I found the used front OEM tire and was really surprised that it did weigh on the digital scale at 8 lbs. Had about 10,000 miles on it. I would have guessed more like 7 lbs by the feel of the tire in my hand. I weighed myself then took a second weighing with the tire in hand. Tire alone on the scale never registered.
If that's how you weighed it, your accuracy is at BEST =/- half a pound! Normal bathroom scales, unless you buy a very costly one, have a couple of important-to-know features:

- They have a huge +/- range
- Many don't even give you the same reading a minute later
- They ALL favor low readings rather than high, as the market is mostly women, and women don't want the truth!

Jim G
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post #6 of 9 Old 08-12-2019, 06:10 PM
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Jim, I only joined the forum because when I googled "OEM weight front rotor R3" your thread came up.

Thank you for asking the same question I found myself asking. I hate threads, and the majority of people on them excluding yourself of course and if anyone takes offense, well I am sure you earned it.

the time people take to type so much negative crap in response to your simple question (last time I checked that is what threads were really meant for) not posting all the other things that threads offer, that have nothing to do with the thread

Anyway, to let you know I am in phase 2 of my R3 road racer, and am hoping to achieve a 52 lb weight reduction and will keep that number honest as I am running a google sheets with weight (projected as for now) but will refine that data and do a total bike weight when phase 2 is finished. Phase 3 will be power plant full mod.

I am limited in access to parts locally so I have to fly them in, suitcases at a time (yeah fun) but even with the phase 1 I did (exhaust/PCVwIgnwAutotune/some aesthetics tail tidy simple stuff) got Hooke and it's time for fly in phase two upgrades.

I will do my best to get back on here and post some data with my phase 2 weigh reduction, but already I am having an issue getting my lightweight swing arm ordered, can't work that issue until end of Aug but hey staying positive except in the credit card department wakawaka

Ok, again, thanks for taking the time to post positive information, I hope I will be able to share some too next month

cheers
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post #7 of 9 Old 08-12-2019, 06:57 PM
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Hey Mark, welcome to the forum! If you read this thread by Jim here, you'll have the full detailed descriptions of his weight reduction program.


https://www.r3-forums.com/forum/289-...ot-racing.html


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post #8 of 9 Old 08-12-2019, 07:03 PM
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And this is relevant as well - he changes the wheels: https://www.r3-forums.com/forum/289-...l-project.html


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post #9 of 9 Old 08-13-2019, 09:49 AM
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I put S20s on a few months ago. Out of curiosity I did look up listed weights at the time: roughly a 4 pound weight reduction over the bias ply OEM. However, these tires are *so* much stickier than the stock Pilots, I can't tell you whether I notice the weight. Suffice it to say, the bike is transformed.
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