Belt Drive

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JAG
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Re: Belt Drive

Good morning half_crazy and pittsy,

Went for a nice ride yesterday. The weather was perfect, full blue sky and not too hot. The old bike ran pretty good.

Thank you half_crazy for the link to calculate RWHP based on weight and MPH. I have used them before. I agree with you, with an experienced rider the calculator and 1/4 mile times are a good way to estimate maximum RWHP.

With your link I came up with 112.16 RWHP for your bike.

I did some quick number crunching with your 1/4 mile times.

So far some interesting results.

60' = 1.73 seconds (35 ft/sec)
330' = 4.80 seconds (69 ft/sec)
660' = 7.3 seconds (90.4 ft/sec) and 94 MPH
1000' = 9.6 seconds (104 ft/sec)
1320' = 11.6 seconds (114 ft/sec) and 115 mph

my findings:

NOTE: These findings do not take account for air resistance. They are also an average rate of acceleration.

0 - 60' = 1.73 seconds - speed reached at the 60' point = 47.3 MPH
Average rate of acceleration during those 1.73 seconds = 1.246 G-force
Linear thrust of 1.246 G-force at 970 lbs. = 1208.6 pounds of thrust

At 1.246 G-force, the force pushing you back would be 1.246 times your body weight. Just holding on must be a challenge.

If you know the rear wheel's outside diameter you can get an idea of the average amount of RWHP you are putting to the ground at the 60' point.

That first 60 feet must be a handful to control, especially at 970 lbs. including the rider. To be honest, I am impressed. Acceleration rates of 1.2 G-force and up are quite impressive for any street bike, especially as I think you indicated, you are probably not at the engine's maximum torque RPM during that first 60 feet.

NOTE: If the 1.73 seconds also includes your reaction time then the G-force acceleration would be even higher.

Thanks again,

Regards,

JAG

half_crazy
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Re: Belt Drive

pittsy wrote:
Your bike is properly "sorted".

Chassis is all factory stock, but for the tires and brake rotors.

pittsy wrote:
Half crazy, on a personal level I'd be interested to know your thoughts now on what constitutes rear wheel torque, but also at forum level.

At this point, all I can do is use the measuring tool that is pretty much the industry standard. What it says the bike makes at the rear wheel is all I have to go by. If you calculate it, it would change with every gear, every increase or decrease in RPM... not to mention weather conditions, elevation above sea level... I'm not so anal that I care that much.

On THIS VERY DYNO, with the same correction factors applied for weather and elevation, the bike in stock form put out 75/92. Now it makes 126/134. The best I can hope to do is see if the modifications gave the desired results. In reality, I was disappointed that it didn't make 130/140, which was the goal. We should have kept the old cams...

half_crazy
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Re: Belt Drive

JAG wrote:
Thank you half_crazy for the link to calculate RWHP based on weight and MPH. I have used them before. I agree with you, with an experienced rider the calculator and 1/4 mile times are a good way to estimate maximum RWHP.

With your link I came up with 112.16 RWHP for your bike.

The Trap speeds shown there are always high (calculator is for cars). I use the ET calculator below and ignore the trap speed.

If you put in 970 lbs and 122 HP it shows almost exactly the ET I ran. On the latest dyno tune the bike made 122 HP before tuning and 126 after.
If you put in 970 lbs and 126 horse it shows 11.50 for an ET, which sounds a bit optimistic to me, but we will soon see...

JAG wrote:
0 - 60' = 1.73 seconds - speed reached at the 60' point = 47.3 MPH
Average rate of acceleration during those 1.73 seconds = 1.246 G-force
Linear thrust of 1.246 G-force at 970 lbs. = 1208.6 pounds of thrust

Thank you for taking the time to do this, but in the real world what will we use this information for? Here's a tidbit for you, whatever reduction you can achieve in the 60' time will be almost twice that reduction in 1/4 mile elapsed time.

JAG wrote:
NOTE: If the 1.73 seconds also includes your reaction time then the G-force acceleration would be even higher.

Your front wheel is between two beams. When you break the forward beam (move) your time starts. If you break the beam too soon you get a red light and you are disqualified. Elapsed time is measured from when you break the beam at the starting line to when you break the beam at the end of the track.

When you launch, your reaction time is displayed on the timing boards at the end of the track, when you break the beam at the end, your ET and MPH are displayed.

pittsy
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Re: Belt Drive

Half crazy said: "The best I can hope to do is see if the modifications gave the desired results."

Keep me informed.

Thanks a lot for engaging in discussion. I've learned a lot through our sparring. Thanks to jag also.

JAG
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Re: Belt Drive

Hi half-crazy and pittsy,

Looks like I may have screwed up my calculations based on half_crazy's 1/4 ET times.

You wouldn't think calculating acceleration and speeds was so complicated. If it wasn't for half_crazy's ET times at different distances and times I would have never caught my errors.

It's been a good experience for me too. I have learned a lot.

What this clearly does show to me is the importance of real world experience and actual measured results.

When I work it out I think I will put it in the power thrust thread. It probably belongs there.

Regards,

JAG

Captain Scarlet
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Re: Belt Drive

"Let me put this just as arrogantly as you choose to take it. Neither of those graphs is a bone stock bike"
... I provided a link to one graph only. The site themselves claim the lower figure is for a stock standard bike. That is 'the facts of the matter', as you put it. But like I said, similar figures aren't hard to find. E.g. http://www.motorcycle-usa.com/71801/Motorcycle-Photo-Gallery-Photo/2011-.... Arrogance isn't particularly attractive and so I retract the clever compliment. Knowing how complex stuff works but acting as though one is never wrong, post proof, doesn't make for an oracle. If you acted less of an idiot savant then people would better warm to your often very interesting and thought provoking contributions.

"Others have been marginalizing this, saying it is somehow getting a softer power application"
... you can dress it up anyway you wish, but it was your example, and it is what it is.

"I was just making the point AGAIN since no one seems to have been listening the last several times I made it"
... maybe change the tone and sentiment if you want folk to value your contributions more?

"Maybe I'm just not fitting in here at the good ol' boy's country club. Maybe it's the language barrier. Who knows?"
... could be, but keep trying. We all like triers. Just don't be right all the time. Even if you are sometimes! ;-D

"It just seems incredible to me that the rear wheel would rotate at that speed (13000 rpm) without bursting."
... road going NSR250RR's used to redline at about 19,000 RPM I think?

"Half crazy, as captain scarlet said. You're a very clever guy, even if your manners are appalling."
... I never said his 'manners are appalling'. I probably wouldn't have been that gracious! ;-D

"If I ever get insulted, I'll let you know."
... oh no you won't, oh yes you will, oh no you won't - it's a pantomime thing, you'll have to Wikipedia it.

"the bottom line is, gearing down means more rear wheel torque, and high revving engines are geared down a lot more"
... thanks for the clear explanation. And the other posts in this thread Kev. I know you do this malarkey for a living, but that's just as well, in terms of you having the gift to deliver laymen terms technical clarity in your posts.

"Point being that this is accomplished through a belt final drive, dispelling the claims made early on in this thread that belt final drive systems are limited to low-torque applications."
... and I for one still agree with you on that, without having to reference Boss Hoss's or tuned American V-Twins. Those more rare examples may put out more torque than the latest production Harley's and Victory's, but the production bikes still put out healthy torque, roughly twice that of a supersport 600. And Victories sell reasonable numbers and Harley still manage to sell 100,000 or whatever each year, without continual warranty claims/law suits for belt breakages and the resultant carnage. That is already proof enough for little 'ole me that belt is a viable option for most road bikes in standard trim.

"Why you are so dead set agaist accepting this is beyond me"
... as your word is unequivocally incontestable, I did wonder what Pitts was playing at myself? ;-D

"I see us doing this as brothers in arms as opposed to enemies"
.... on a you're hiding nothing to (anag).

"We both must feel fairly strongly about this"
... stop being so competitive you two. Play nicely! :-D

"Chain or belt?"
... I would just like to take this opportunity to thank you JAG, for remembering what the bloody thread is supposed to be about! I don't give a monkeys what a VicZX-Eleventy V8 makes at the third cleft spiggot. I just want to conjure why belt isn't perceived as a good alternative for a lot of mainstream naked, adventure and lightweight touring bikes? Matters not how much bigger my todger is than the next or not. Except to Miss S, natch.

I'm usually all for threads veering off at a fractal tangent. One thread I started on the TeX forum ended up being a lengthy multi page chat about which was the best biscuits (cookies) you can buy. And jolly interesting reading it was too, especially as a garibaldi and chocky bourbon fan!

However, it would be good to perhaps reign this one back in from power claims and the measuring thereof, back towards the technical or even gut feelings as to why belt isn't the preferred option of manufacturers by choice?

pittsy
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Re: Belt Drive

Captain scarlet said: " I don't give a monkeys what a VicZX-Eleventy V8 makes at the third cleft spiggot. "

Am I right in saying the first part of that sentence dismisses half crazy and second part dismisses me?

If we're going to compare chains and belts (which was the point of the thread) you'll need to know. I'm convinced I was wrong saying that belts are limited to relatively low power bikes. Well, out of date let's say. My original comments were taking in mind the use of HTD belts, which seem to have been superseded by the "polychain GT" type, using a different tooth profile, as well as other differences. (I notice the latest thing is polychain carbon, claiming another 25% better rating).

Captain scarlet said: ". ""It just seems incredible to me that the rear wheel would rotate at that speed (13000 rpm) without bursting."
... road going NSR250RR's used to redline at about 19,000 RPM I think?"

I was referring to the rear wheel. You'll need to read a few posts to understand the context of why I said that.

Captain scarlet said: "Harley's and Victory's, but the production bikes still put out healthy torque, roughly twice that of a supersport 600."

In what gear? Don't forget, a belt (chain/shaft) is attached to the back wheel and so is affected by the gear being used. I would go so far as to claim that being a FACT.

I've not seen one these threads yet, that doesn't veer off onto different, but obviously linked topics. They're linked! The torque/power thang will raise its head in connection with a host of other related topics. We're talking motorcycles!

half_crazy
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Re: Belt Drive

Captain Scarlet wrote:
maybe change the tone and sentiment if you want folk to value your contributions more?

You can tell "tone" and "sentiment" by reading a post here? Amazing...
I'm not here to win your approval. If you value my contribution, great, if not, that's great too.

Captain Scarlet wrote:
However, it would be good to perhaps reign this one back in from power claims and the measuring thereof, back towards the technical or even gut feelings as to why belt isn't the preferred option of manufacturers by choice?

It is the preferred system for some manufacturers.

half_crazy
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Re: Belt Drive

pittsy wrote:
Keep me informed.

My friend, I am done with chasing power from this bike. I will ride it as is until the engine wears out. Maybe when that happens it will get bored to 116 cubic inches and make 140/140... but that will be a few years out. A rebuild is cheaper than a new bike and it's such a good daily driver that I'll probably keep this one forever no matter how many bikes I have.

JAG
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Re: Belt Drive

Hello half_crazy,

I for one am grateful for your contributions. If it wasn't for your hard data and comments about your drag racing experiences and how the ET times are done I would have continued making wrong calculations resulting in incorrect conclusions.

It was a pleasure having someone like yourself of your experience to communicate with. Thankyou.

Pittsy always has provided interesting and valid points of view. His poor old Kawasaki has been a real workhorse for me. His suggestions in the power thrust curve thread helped me a lot.

Our Captain Scarlet's extensive experience with so many bikes is also a great asset for me, plus he's a very good word smith. I have no idea how he can write so well on so many topics.

Regards,

JAG

half_crazy
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Re: Belt Drive

Thank you, JAG. I'll have to check out the thrust thread.

pittsy
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Re: Belt Drive

Pittsy said: "In my eyes a fact is an interpretation of data. As such it is liable to change. A good opinion could quite conceivably change a fact."

Half crazy said: "We can all choose to ignore the facts, but it will never stop them being the facts.
I don't believe in gravity or math... funny thing though, when I drop something it still falls straight down and if I have 2 apples and someone gives me 2 more I still have 4 apples. Evidently, what I believe is inconsequential."

When viewd from "space" and as a consequence of the earth spinning on its axis, whilst at the same time orbiting the sun, which in turn orbits the centre of the Galaxy, which in turn..........if we traced loci of the tips of your fingers and the object you let go, woundnt both the loci trace rather strange three dimensional curves, until the object came to rest on the ground? You say it drops straight down. I say you and it move away from each other in a weird curve.

Captain Scarlet
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Re: Belt Drive

"Our Captain Scarlet's extensive experience with so many bikes is also a great asset for me, plus he's a very good word smith. I have no idea how he can write so well on so many topics."
... thanks for that comment, JAG. Acknowledging it three or four years later is a forte of mine :-D But we should not confuse experience with knowledge. For I and Jimi Hendrix are Experienced, but pittsy is knowledgeable. I.e. He knows about apples and stuff :-D

pittsy
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Re: Belt Drive

CS said: ".......but pittsy is knowledgeable. I.e. He knows about apples and stuff"

One hit me on the head once. Well, the back of the head, to be honest. Someone threw it at me. :D

Knowledgeable! Er, that's all relative. I'm just an ape who thinks too much (and sometimes likes to play Devils advocate).

kharli
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Re: Belt Drive

Wow I read all that ! What I am looking for is a definitive answer to power losses between belt and chain ,,and shaft if anyone can throw that in . In rough percentage figures . The figures I pull from the net say chains 5% Belts around 14% and shafts around 20% but when I quote these I am disbelieved so I am returning to the one font of accurate information and sensible replies . cheers !