‘23 V4S stock forged wheels vs BST wheels

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panibadboy said:
With the fact that he was praising the effects of CF wheels that basically hide the issues with suspension setup.
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Okay so assuming that all things are equal and the suspension is set up well, are you arguing the reducing the rotating mass on the wheels by 2 to 4.5 KG doesn’t affect handling and how the bike feels?

If so I doubt you’ve ridden a bike with reduced rotating mass, and are simply voicing your opinion, instead of direct experience…because I’ve ridden back to back sessions after wheels changes at track between a heavier rotating mass setup and a lower one, and the difference is both pronounced and undeniable…whether that leads to faster lap times depends on many factors including how technical the track is or isn’t, rider skill etc…but with 100% certainty I can tell you that a bike with the same power and suspension setup FEELS way more lively and FUN with lighter rotating mass…and certainly doesn’t HURT lap times in any situation.
 
Light wheels are marginal gains. Cast >>> forged alu > forged mag ≥ carbon.

But even modern cast alu wheels are much better than the were 5-10 yrs ago. In WSS, they have to run the stock wheel and the championship winning V2 (which isn’t a far cry off the stock as far as I can read front the rulebook) can lap 7 sec quicker than a stock V4S at Jerez. Granted, the rider probably has a lot to do with it but my point is that heavy wheels are the least of a track day rider’s problem
 
SuperDomestique said:
Light wheels are marginal gains. Cast >>> forged alu > forged mag ≥ carbon.

But even modern cast alu wheels are much better than the were 5-10 yrs ago. In WSS, they have to run the stock wheel and the championship winning V2 (which isn’t a far cry off the stock as far as I can read front the rulebook) can lap 7 sec quicker than a stock V4S at Jerez. Granted, the rider probably has a lot to do with it but my point is that heavy wheels are the least of a track day rider’s problem
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Theres so much bollox in this statement we are going to need a wheelbarrow to carry them!
 
panibadboy said:
Hey mate, English is not strongest language but even I could comprehend whats written here

On the road, however, the effects of the BST wheels were more obvious and universally appreciated. More suspension compliance and better bump absorption (due to being able to run less fork and shock damping. Which made the bike more stable over mid corner bumps. With more time spent in the lower gears, the rate of acceleration due to lower MOI, resulted in more effortless acceleration (limited by TC/traction of course). Bike just felt lighter in all respect which was a great thing. The flightiness felt on the track wasn't reproduced on the road due to the lower speeds and lesser lean lean angles. And all these differences were abundantly noticeable on the V4R which already had reasonably light forged rims. I did the same test on my KTM Superduke which came stock with heavy cast boat anchors for wheels. And the difference was truly profound. Even more obvious than the effects I felt on my Duc.


Get suspension sorted on your street bike. I don't care much that you have v4r.
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Ah, I understand your confusion. Let me try to clear it up for you. Less rotating and/or unsprung mass allows you to back off on rebound damping since there is less mass being pushed by the expanding spring. So you ask, why not just run heavier wheels and more rebound damping? Well the answer is very simple. You want as little rebound damping as possible in order to keep a consistent contact patch (tire to pavement). If fact, you generally want to keep backing off of rebound damping until just before the bike starts to feel floaty. Many benefits of being able to run less damping (both C and R) that I'll be happy to get into the discussion takes us there. Also, many downsides to running too much damping (inconsistent contact patch, excessive tirewall deflection, poor ride quality, heating up shock/fork oil, shock ratcheting, etc,.).

Again, in no way am I saying go for light wheels in order to dial in your suspension. What I'm saying is that light wheels often require additional damping adjustments in order to get the suspension optimized. Without these additional adjustments, you will likely be running more damping than you need to. I can always invite my good friend Dave Moss who is very talented with suspensions set-up to the discussion. We have done a lot of work together over the last several years and I'm sure his input would be welcome.
 
The difference is three lbs less than 1 on the front according to the original post. Yes you can reduce the damping a bit but I will still argue that I can shorten the trail and get the same turn in and ability to flip it from side to side with forged wheels. Good for poseur perk but too expensive for the performance gain.
 
baggerman said:
The difference is three lbs less than 1 on the front according to the original post. Yes you can reduce the damping a bit but I will still argue that I can shorten the trail and get the same turn in and ability to flip it from side to side with forged wheels. Good for poseur perk but too expensive for the performance gain.
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With all due respect, I don’t think you have a firm grasp on this topic. The effects of changing trail is different than the effects of reducing unsprung mass. Sure, you can do different things to get similar (but not the same) results. But each different thing has its own unique effect (and side effect). I’d suggest talking with a competent crew chief or chassis guy and pitching your beliefs to him.
 
OpenFlash Performance said:
With all due respect, I don’t think you have a firm grasp on this topic. The effects of changing trail is different than the effects of reducing unsprung mass. Sure, you can do different things to get similar (but not the same) results. But each different thing has its own unique effect (and side effect). I’d suggest talking with a competent crew chief or chassis guy and pitching your beliefs to him.
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Specifically if you shorten the trail you get a quicker turning bike, but lose some straight line and braking stability. That you then have to correct somewhere else in the geometry, and becomes a rabbit hole of sorts, which is fine if you are into that kind of thing. The only real negative to losing ALOT of rotating mass is that you lose some gyroscopic forces that contribute to a feeling of less stability on the bike because it feels so much lighter. But that’s a negative that turns into a positive when you get use to it. More flickable.

I would argue that it’s not an ‘either/or’. Get the suspension dialed in the way you LIKE it, if that’s with sharper turn in and faster turning at the cost of straight line and braking stability as your preference in setup do that, but even after that’s done the bike will still feel lighter and better with less rotating mass.

It should go without saying with this very educated crowd that reducing rotating mass has a compounding affect on the feeling of weighty-ness. And on how well the bike accelerates and brakes. Anecdotally I’d say it’s about 7 to 1, meaning for each pound of rotating mass you reduce, it FEELS like you lost 7 pounds of static mass. Overall I think I’ve dropped roughly 11 pounds of rotating mass off my bike, which in turn FEELS like dropping 77 pounds off the bike…that’s huge even on liter bikes…affects how the bike feels so much that when I ride other peoples bikes they feel heavy and leaden to me. The HP4 Race I rode was the only liter bike I’ve ridden that felt close as quick and nimble.
 
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Steven31371 said:
Specifically if you shorten the trail you get a quicker turning bike, but lose some straight line and braking stability. That you then have to correct somewhere else in the geometry, and becomes a rabbit hole of sorts, which is fine if you are into that kind of thing. The only real negative to losing ALOT of rotating mass is that you lose some gyroscopic forces that contribute to a feeling of less stability on the bike because it feels so much lighter. But that’s a negative that turns into a positive when you get use to it. More flickable.

I would argue that it’s not an ‘either/or’. Get the suspension dialed in the way you LIKE it, if that’s with sharper turn in and faster turning at the cost of straight line and braking stability as your preference in setup do that, but even after that’s done the bike will still feel lighter and better with less rotating mass.

It should go without saying with this very educated crowd that reducing rotating mass has a compounding affect on the feeling of weighty-ness. And on how well the bike accelerates and brakes. Anecdotally I’d say it’s about 7 to 1, meaning for each pound of rotating mass you reduce, it FEELS like you lost 7 pounds of static mass. Overall I think I’ve dropped roughly 11 pounds of rotating mass off my bike, which in turn FEELS like dropping 77 pounds off the bike…that’s huge even on liter bikes…affects how the bike feels so much that when I ride other peoples bikes they feel heavy and leaden to me. The HP4 Race I rode was the only liter bike I’ve ridden that felt close as quick and nimble.
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Exactly. My buddy Eric successfully races a Superduke in AFM. It's done a lot of work on getting the trail optimized. He even manufactured his own adj triple clamps which he now sells to other owners. Before the triple clamp, he had to adjust trail by playing around with front and rear right height. He had to raise the back so much that he even had to design a new shock linkage that offers more clearance between it and the shock. And then he found that in order adjust the trail for improved steering in and out of a corner, the braking stability was compromised. So exactly what you referred to as going down that rabbit hole. He has a great YouTube channel talking about motorcycle dynamics/set-up/etc,. It's worth watching if you are into motorcycle tech.

https://www.youtube.com/@superduked33
 
OpenFlash Performance said:
With all due respect, I don’t think you have a firm grasp on this topic. The effects of changing trail is different than the effects of reducing unsprung mass. Sure, you can do different things to get similar (but not the same) results. But each different thing has its own unique effect (and side effect). I’d suggest talking with a competent crew chief or chassis guy and pitching your beliefs to him.
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It's two things unsprung mass and lessened gyroscopic forces. Shortening the trail will lessen the gyroscopic force you feel at the bars. Simply as that. The couple of pounds of extra unsprung mass can be tuned out. Want to get rid of some rotational weight take the alternator rotor off and run constant loss or put an early belt drive alternator on.
 
Steven31371 said:
Okay so assuming that all things are equal and the suspension is set up well, are you arguing the reducing the rotating mass on the wheels by 2 to 4.5 KG doesn’t affect handling and how the bike feels?

If so I doubt you’ve ridden a bike with reduced rotating mass, and are simply voicing your opinion, instead of direct experience…because I’ve ridden back to back sessions after wheels changes at track between a heavier rotating mass setup and a lower one, and the difference is both pronounced and undeniable…whether that leads to faster lap times depends on many factors including how technical the track is or isn’t, rider skill etc…but with 100% certainty I can tell you that a bike with the same power and suspension setup FEELS way more lively and FUN with lighter rotating mass…and certainly doesn’t HURT lap times in any situation.
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your math is totally off mate

BST Carbon Fibre Wheels*
Front: 2.480 Kg
Rear: 4.002 Kg

1704489397303.png



I have no idea how you come up with 2kg. But who cares any way - whatever good for Starbucks, good for everyone
 
More important than just comparing wheel weight, it’s more useful to compare where the mass is located on the wheel. Most of the weight on a BST wheel is in the hub portion of the wheel. The outer rim is very light and much lighter than a forged aluminum wheel that may only weight slightly more overall. But we all now that the effects of rotational mass increase the further away from the center of rotation. Hence why the effects of CF wheels are so evident upon riding.
 
Dunlop brought out a 120/70 (soft DOT) that's about 10% shorter than the current ones. So I put one of those on a forged wheel and a normal height one on the CF wheel. Then I blindfold you... I'm going to try one at some point. Should turn in more readily. Has to be lighter and that weight is further out yet.
 
The short version for most people is forged OEM will do fine but if you're inclined to change then get the wheels you like and can afford, it's not going to make a life changing difference. No need to be a Luddite, carbon wheels have proven benefits but there are a couple of minor negatives as discussed.
Performance improvement is always a case of knowing when to stop as there is literally no limit to how much you can spend to get ever decreasing gains FYI MotoGP bikes are only 1 or 2 % faster than WSBK bikes on the same tracks despite millions of development dollars between them, arguing the benefits of carbon vs forged wheel etc is not an argument thats worth winning.
 
Reminds me of arguing the difference between ........ like say 54 DD and Small Tits as in an A-Cup. But both are natural ones of course, not those silicone jobs.
 

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