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When/where does weight matter the most?

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My buddy and I were talking the other day about the light weight of the new KTM 450 SX.  He's a die hard Yamadawg, I bleed orange.  When I mentioned the weight difference being 11 lbs, he responded that it doesn't matter especially since he's 6' tall and 40 lbs overweight. 

 

But the Yamaha has handling issues on corner entrances, and it feels vague in the corners according to the reviews I've read.  I wonder how much the extra weight adds to these Yamaha drawbacks.  Frame geometry is a factor too, I'm sure.  They focused so much on centralizing the mass, that they forgot to reduce the mass.

 

Obviously 11 lbs of unsprung weight would be detrimental to the bike's handling (been there dun that with double wrapping HD tubes to prevent flats).  11 lbs around your gut would be sprung weight.. and I would think 11 lbs on the bike, unsprung or sprung, would affect your riding more than 11 lbs on your body.  Am I alone in this?

Edited by LovingOffroadPain
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I think you read too many MXA reviews. You should go ride a Yamaha and decided for yourself if the weight matters.

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Where you went wrong in overthinking this is you forgot to take into account the superior engineering of the Japanese motorcycle builders. 11 pounds with their engineering skill is meaningless. 😉

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I don't think 11lbs matters. I think the logic of it not mattering because hes a big overweight guy is flawed.

We know the weight difference isn't a difference in un-sprung weight so we can take that variable out of the equation. But yes unsprung weight impacts performance more than sprung weight. 

I think the suspension, how its set up, frame geometry, tires and riding technique/body positioning are going to have way more impact on corner entry than 11lbs. Corner entry behavior is pretty subjective anyways. 

 

For conversations sake... changing the weight of the bike will have more of an impact on the performance of the bike than increasing weight of the rider assuming the suspension is always designed for the weight of the bike and set up properly for the rider. It also greatly depends where that weight is added and how it impacts the center of gravity of the bike. Centralizing and optimizing mass have much more impact on performance than reducing it when we're talking about 11lbs. If we were talking 40lbs than reducing mass would have a greater impact.

Changing the weight of the rider doesn't have much of an impact on the performance of the bike because you can dynamically change your own center of gravity and as such, the dynamic center of gravity of the bike/rider unit. A heavier person is going to have more influence over the dynamic center of gravity but that involves body positioning and technique so it pretty much becomes a moot point.  

 

11lbs isn't really enough for anyone to notice unless the weight change made a massive change in the center of gravity and we know that isn't the case. 

 

So in short, the physics of it tell us a weight difference of the bike itself impacts bike performance more than weight difference of the rider. In your buddies case, an out of shape, overweight rider has their own performance issues independent of the bike (endurance, strength, range of motion..etc)

Edited by SenorThumpy
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Front end feel is completely subjective. People have been complaining about Yamaha handling since long before the reversed cylinder or mass centralization. But every weekend there are people hauling the mail on them at the track and trails.

As for the extra weight, just think about where that weight is going to show up. Rapid accelerations of the chassis. The two places it would be most noticeable, single track where you are throwing the bike around, and corners where you are trying to rapidly lean the bike over. The difference is easily experienced riding a 250 two stroke and a 450 back to back. it's easier to quickly lean and cut down on the 250. So think about an 11 pound difference. Negligable.

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Wait cannot be entirely subjective or no bike would handle corner better than any other! Nothing would be good or bad in this world!

Saying that weight does not matter is like saying that heifer Sally's 300 pound ass did not prevent her from getting laid it in high school.

Last Saturday, I could feel the mud way to packing onto my bike is I rode. I could feel it while I rode, while I loaded the bike, while I unloaded the bike, it was detrimental to how well the bike handled.

Saying that handling is completely subjective is like saying that the 1997 CR 250 chassis was only stiff on a subjective basis! Whatever guys, the Japanese need to go on a diet.

But that was not my point of this. You guys turn that into the point. My original intention of this thread was to discuss weight distribution and where it matters.

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Too many factors to say if 11 pounds is a positive or negative thing.

Assuming you have two identical bikes, weight placement can have a huge effect. Imagine 11 pounds sitting on your forks. (like a head light and instruments/horn/signals/mirror). Or 11 pounds on the rear fender. Or 11 pounds under the engine (below axle center line).

But to compare two bikes, with different distribution of weight, frame geometry and a myriad of other things is like arguing about which direct is better, east or west. In truth, if one goes east and the other west, they will eventually end up meeting at the half way point around the globe.

 

Lighter is generally better. But a lighter bike with all its' mass up high will feel heavier than a heavier bike with all its' mass down low.

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Wait cannot be entirely subjective or no bike would handle corner better than any other! Nothing would be good or bad in this world!

Saying that weight does not matter is like saying that heifer Sally's 300 pound ass did not prevent her from getting laid it in high school.

Last Saturday, I could feel the mud way to packing onto my bike is I rode. I could feel it while I rode, while I loaded the bike, while I unloaded the bike, it was detrimental to how well the bike handled.

Saying that handling is completely subjective is like saying that the 1997 CR 250 chassis was only stiff on a subjective basis! Whatever guys, the Japanese need to go on a diet.

But that was not my point of this. You guys turn that into the point. My original intention of this thread was to discuss weight distribution and where it matters.

Front end feel is subjective. He didn't say weight was.

 

The mud you rode in wasn't designed into the chassis.

You made it sound like you were bashing Yamaha (I don't know if that was your intention or not) by paraphrasing an MXA review.

FWIW, my 250FX is spec'd at an even heavier weight than the 450, at 247 lbs. It is the best cornering bike I have owned, includding my KTM250exc and YZ250.  I only notice the weight on technical downhills, and only because I suck on downhills and go too slow.  A 450 does have more gyroscopic effect from the motor, making it harder to lean over. Beside that, I don't know what the problem with the 450 is. Since I haven't ridden one and I don't know what 'vague' means in MXA's terms.

 

Since I haven't ridden the 450, my best guess is that the 11 lbs doesn't matter, and they needed to run more sag. This is based on the fact that I ride a bike with a similar design that weights 9 lbs more and handles just fine. No doubt shaving some weight probably wouldn't hurt.

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Interesting topic and Dirt Bike has a pretty good review of the YZ450FX vs the 450XC-F (not the SX) and they say the YZ is 23ib heavier without gas http://dirtbikemagazine.com/home-features/off-road-shootout-ktm-450xc-f-vs-yamaha-yz450fx

 

Now with that said my normal ride is a 05 CRF250R and I've recently had the opportunity to do a few rides the KTM 150SX (awesome nimble light weight woods weapon) and I've done a  a lot of rides on an older DRZ400E. I'm not going to find all the weights but lightest to heaviest  150SX, 250R, 400E.

 

Overall  IMO I think bike weight effected me more but I really could not appreciate the weight difference when I first started riding. Now I can understand the bike weight but it does really effect how I ride - not sure if this makes sense.

 

For example about a year ago my 250R was done and we where going on a 4 day trip to an area where IMO the 250R works awesome but there was some STEEP hills where I struggled. The 250R was down so I borrowed the 400E. Honestly I did not notice the weight and in fact the 400E made the steep hills easy and actually help me go back and do them on the 250R.

 

I'm stoked to see the Yamaha is stepping up with the FX and at least they have 2T.

 

IMO I get the US vs world wide market for bikes but really we live in an incredible time for dirt bike options but the future is off road/enduro etc and if the big 4 do not step up they are going to lose out in to KTM, Husky, Beta,

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I'm not sure about the bikes so much, but 11 lbs extra on a woman is a huge problem!!

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Lighter is generally better. But a lighter bike with all its' mass up high will feel heavier than a heavier bike with all its' mass down low.

A good example of this is in the adventure bike segment.  The new Honda Africa Twin is 10-20 pounds heavier than a KTM 1190, but if you sit on them both and do the classic bike shake between the legs test, the Honda feels lighter and smaller.

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I have a really big heart that has come in handy more than once

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Last Saturday, I could feel the mud way to packing onto my bike is I rode. I could feel it while I rode, it was detrimental to how well the bike handled.

Yeah. Right. Sure you could feel a 1% difference

Let me guess. When a tire wears down and loses 1 oz of weight you can feel that too? Or when you go down 1/4 tank of fuel too?

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Just ride the dam thing!3oy7d1.jpgIf someone is worried about any motorcycle weight they need to hit the gym and pump some iron. most bikes have a nice power to weight ratio, so one should be able to cope! If not try bad mitten, or cricket, or perhaps tiddly winks!beavis-and-butthead-settle-down-t-shirt-6.jpg

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Yeah. Right. Sure you could feel a 1% difference

Let me guess. When a tire wears down and loses 1 oz of weight you can feel that too? Or when you go down 1/4 tank of fuel too?

You've obviously never ridden or raced in a mudder where clay is prevalent such as Ohio or Georgia. You can easily pack 70 or 80 pounds of mud on the bike. And you most definitely notice it when you're digging the bike out of a bad rut you got stuck in! Heck, I've had a race where at least 5 pounds of mud has built up on each boot. 20 pounds on my enduro jacket.

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Yeah. Right. Sure you could feel a 1% difference

Let me guess. When a tire wears down and loses 1 oz of weight you can feel that too? Or when you go down 1/4 tank of fuel too?

No, I prolly gained 20-30 lbs of mud. I had to scrape it off with my hands. It's not 1% it's more like a 10% increase.

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The slower you go the more the weight matters. 1st gear technical riding will prove it. Even with modern mass centralzation ,which helps, you feel it.

The tough guy just work out idea isn't always readable. There are guys here with bad knees, shoulders, wrists... Alot of older guys migrate towards lighter bike's.

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Yeah. Right. Sure you could feel a 1% difference

Let me guess. When a tire wears down and loses 1 oz of weight you can feel that too? Or when you go down 1/4 tank of fuel too?

Just thought I'd throw in a pic for reference 😉

DSC_1640.jpg

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The slower you go the more the weight matters. 1st gear technical riding will prove it. Even with modern mass centralzation ,which helps, you feel it.

The tough guy just work out idea isn't always readable. There are guys here with bad knees, shoulders, wrists... Alot of older guys migrate towards lighter bike's.

 

That makes sense.  My buddy rode my 300 on that muddy day, and I rode his 450 which was also packed with mud.  Suddently I couldn't keep my buddy in sight!  I was gapping him, and he was gapping me on the 300.  In his words, "Man these two strokes are so flickable!  I love my 450 for faster stuff, but this trail you've cut out here is TIGHT."

 

Two strokes are def better for tighter riding.  I agree.

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lol The ol miserable mud slog! Reminds me of a certain hare scrambles race I did yrs ago. Doable the first lap or 2.. Then you come around later in the race, and its looked like that. You felt like you won the lottery after you finally got tho it. 

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