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How much impact does weight have on the grom

This is a discussion on How much impact does weight have on the grom within the Off-Topic forums, part of the Honda Grom Forums category; I see a lot of people cutting little bits of weight here and there and saying cutting like 1 pound of weight is significant on ...

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    How much impact does weight have on the grom

    I see a lot of people cutting little bits of weight here and there and saying cutting like 1 pound of weight is significant on this bike. In reality though how much of an impact does small weight savings actually have?

    A non ABS stock grom weighs about 229lbs and produces 8.6hp so the power to weight ratio is .0376. But in the real world how does that translate to acceleration and top speed? What can you compare it to? Say you add 5 pounds to that and get 0.368. How much of a difference is that?

    Basically I think people overestimate how much of an affect weight has, but I'm curious how/if we can prove that one way or another.
    2014 Grom
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    The most important weight to remove is rotating.

    Think wheels, rotors, and rotating parts on the crank shaft.


    Static, sprung weight helps of course, but after the obvious stuff the cost/benefit gets pretty bad.

    It's hard to quantify, especially with small changes, but once you add them all together there can be appreciable difference.

    Remember that people overestimate the effectiveness of pretty well everything they do to their bikes. The combination of money spent as well as the addition of ego (I did this therefore it's worthwhile) is very powerful. Combine that with a website full of stories from people who feel the same way and confirmation bias takes over. Very few people do any actual validation of the effectiveness of their work, so take it all with a grain of salt and consider the cost per benefit.

    Light wheels are the best single modification you can make to any bike. They transform the handling in a way nothing else can.
    Last edited by Wibbly; 07-15-2019 at 12:49 PM.
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    ^ truth. very much so. small differences definitely add up but holy crap does it get difficult and expensive to make any real difference. it took me a LOT of time and expense to drop 110-120 lbs off a stock bike (rd350 custom frame, etc), and its noticeable for sure, but was more an engineering exercise than anything. I don't recommend it. lol. But it was fun to me.

    an easy way to translate the HP to weight ratio into a relateble number is (for some) to compare it to cars. so, lets say a 2290 pound car has 86.0 hp. will adding or removing 50 lbs to that cars overall weight make that huge of a difference? probably not.
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    A bunch of old stuff that runs. 2stroke grom build...in process.. eventually...

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    My Grom weighs 214 pounds for a ratio p/w of 0.4018.

    I think rider weight can introduce a larger variable. Taking total weight of bike and rider and dividing it into horsepower would yield more realistic results. My total (bike+rider+clothes+shoes+helmet) is ~355 lbs. and assuming the stock benchmark of 8.6 hp yields a p/w weight ratio of .0242 hp/lb. My DRZ is .0788... three times more power to weight. (lol)
    2018 GROM: Modified for reliability longevity gas mileage... and fun.

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    best change besides Kitaco clutch side cover is , carbon fiber wheels, pricey but from all the grom owners that have them said it made the biggest difference.

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    Weight is everything. As was mentioned, rotating mass is the best weight to reduce, but any weight reduction is good for performance.

    Sometimes the easiest way to drop weight on a bike is to put the rider on a diet...

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    When I first started looking at these forums I remember looking into the HR shift shaft support. One of the posts was "how much does it weigh?" Like this tiny piece of aluminum weighs 20 pounds. That and the difference between o-ring chains and non o-ring in that the o-ring causes more drag. It's just something that's stuck in my head and made me think does it really matter that much? You can go take a nice dump and have more weight savings than buying that $100 lighter whatever.

    Rotational mass aside I was just looking for a way to prove it one way or the other and you guys make good points.
    Last edited by LordSquirrel; 07-15-2019 at 03:18 PM.
    2014 Grom
    Takegawa 143cc kit with S stage cam
    Kitaco clutch cover
    Takegawa oil pump with SUP modded catch
    PCX 150 injector
    SMR 6 disc clutch and 30% springs
    Koso clutch plate
    Opmid temp gauge
    Innovate MTX-L Plus AFR gauge
    EFIE
    Ebay exhaust, intake, and a bunch of other parts
    Seat Concepts seat
    OTB chain adjusters w/ spool
    14T/36T sprockets
    Pirelli SL26 tires

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    Quote Originally Posted by LordSquirrel View Post
    When I first started looking at these forums I remember looking into the HR shift shaft support. One of the posts was "how much does it weigh?" Like this tiny piece of aluminum weighs 20 pounds. That and the difference between o-ring chains and non o-ring in that the o-ring causes more drag. It's just something that's stuck in my head and made me think does it really matter that much? You can go take a nice dump and have more weight savings than buying that $100 lighter whatever.

    Rotational mass aside I was just looking for a way to prove it one way or the other and you guys make good points.
    Adding or removing 2 ounces isn't going to change performance a perceivable amount. But continually removing or adding ounces here and there can have big impacts.

    And doing it smart is the key. Sure, the Hard Racing shift shaft support weighs next to nothing, but it also doesn't do a single thing IMO. I added that weight thinking it would improve shifting and it does not. It's just unnecessary additional weight.

    This article claims to have removed 38 pounds from an OG Grom.

    https://www.motorcycle.com/manufactu...roadracer.html

    How much impact does weight have on the grom-9dbd4a52-2280-426a-bf20-57b49410b164.jpeg

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    I did some reading around, and the general consensus is one pound of rotating weight is worth about 2 pounds of static weight.
    2018 GROM: Modified for reliability longevity gas mileage... and fun.

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    Wow... the article claimed a 187 pound Grom! That's inspirational
    That's close to the weight of my Ruckus.
    At 214, I got a LONG way to go! (lol)
    Last edited by tooter; 07-15-2019 at 08:03 PM.
    2018 GROM: Modified for reliability longevity gas mileage... and fun.

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