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Ste
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PostPosted: 14:10 - 04 Mar 2018    Post subject: Reply with quote

It's no longer a supermoto if you fit knobbly tyres. Wink
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M.C
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PostPosted: 14:49 - 04 Mar 2018    Post subject: Reply with quote

Ste wrote:
It's no longer a supermoto if you fit knobbly tyres. Wink

Well the DT 125 SM also had an larger front brake disc over the standard model but the tyre thing was kinda my point.
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Teflon-Mike
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PostPosted: 15:19 - 04 Mar 2018    Post subject: Reply with quote

M.C wrote:
I guess someone should let supermoto manufacturers know they should be fitting knobblies to their bikes.

They probably should.. or simply not have taken the knoblies off a perfectly good MX bike to fit Road-Race slicks to the things, to make a mongrel of compromises with table top landing gear for suspension to tear around a relatively flat dirt-track!?!?!?

But then that's 'Marketing' for you...... the science don't matter very much to the sales figures and profit/loss book....

And if customers scare themselves having a tyre do a little jidder, and will use that to convince themselves they need EVEN fatter tyres as well as how much of a riding godd they must be to have 'saved' the full on tank-slappa... so much the better for floging even more bikes with overly wide rubber specced by the marketing men......

Seriously, a pretty average clubman push bike racer, weighs in at something like 80Kg; the actual bike adding about as much as a 'family' size bag of snax! And on a dyno, they can record a 'sustained' power-output more than a moped engine... 3bhp or so..... and for what they would term 'briefly' as in a mock 'break' or sprint, lasting maybe five minutes, as much as 8-10bhp.... And they put that sort of power to the road through tyres that are a mere 10mm in cross section, and perhaps only 2-3mm thick on the crest! They have to pump the things up to three figure psi's to stop the rider's weight crushing them on such a tiny contact patch, measured in square mm rather than square inches!

You REALLY don't 'need' 140 or more section rubber to support the weight or handle the paltry power of a 125cc motorbike, or stop it 'skiddding'!!!!

You don't even need that much rubber, 'really' to support a 200Kg bike with rider and pillion and luggage, and handle 100+bhp..... Just a bit of savvy.. like looking at the road for surface chit and NOT riding through it, banked over at speed, if you can help it! THAT no tyre width, compound or tread pattern can compensate for!

You put knoblies on tarmac? REAL knoblies, that is, not designer 'Adventure-sport' road tyres or old fashioned block-treads..... a) you wont be on them for long.... you'd swear some-one had fitted square wheels before your fingers went numb b) they wouldn't last very long before you had a slick, at least in the middle c) it would be even odds whether you'd be cursing either ahead of dreaded 'tread creep'.... and they STILL wouldn't do bog all for 'grip' even on a slurried road, because the knobles are designed to dig into peat and transmit force through actual mechanical contact and viscous resistance, not friction, and to do that the actual knobles are often as hard a rubber as they can get to act like paddles, and not just bend like a tea-spoon when put under load!

But hey, don't let the facts disued you from your prejudices, the marketing men wouldn't be able to meet their payments on the holiday home!
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M.C
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PostPosted: 16:35 - 04 Mar 2018    Post subject: Reply with quote

Teflon-Mike wrote:
M.C wrote:
I guess someone should let supermoto manufacturers know they should be fitting knobblies to their bikes.

They probably should.. or simply not have taken the knoblies off a perfectly good MX bike to fit Road-Race slicks to the things, to make a mongrel of compromises with table top landing gear for suspension to tear around a relatively flat dirt-track!?!?!?

But then that's 'Marketing' for you...... the science don't matter very much to the sales figures and profit/loss book....

So what about the supermoto racers? Looking at pics they seem to like slick or semi-slick tyres (I don't see any knobblies).
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ThatDippyTwat
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PostPosted: 17:02 - 04 Mar 2018    Post subject: Reply with quote

M.C wrote:
Forgive me if I don't trust BCF logic (can't hear loud exhausts when they're behind you etc.).


They echo, the sound is reflected off buildings etc. Deeper notes are better heard than higher ones, and typically free flowing cans will ahve a deeper note.
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Teflon-Mike
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PostPosted: 18:30 - 04 Mar 2018    Post subject: Reply with quote

M.C wrote:
So what about the supermoto racers? Looking at pics they seem to like slick or semi-slick tyres (I don't see any knobblies).

What about them? Its a very artificial class, to start with, picking a highly specialised dirt bike, and trying to mod it for road use, then find a course that the resultant mule favours!

It would be like taking a Massey-Furgason tractor.... fitting funny-car dragster tyres, and an turbo-charged F1 engine, and trying to race it in a World Rally Championship.... crying 'foul' when a Subaru kicks its arse and then writing a set of rules, specifically for F1 engined, drag tyred farm tractors to race in!

BUT, AFAIK, they use the softest, stickiest tyre permitted by the regulations for the class... same as any other.. they have just written them rules to suit the special they have created!

Though, perversely, a lot IS still down to them marketing men, who really DGAS how quick a bike can get round a track, or what is technically the best way to do so, but flogging spectator tickets or TV rights and getting the poor buffoons on the bikes top put on a show... where having them slip and slide about is all so much more spectacular than if they did it properly!

In trials, where the 'regulation' block treads size and tread pattern is very well defined in FIM/ACU law, and the 'trials-slicks' we use are that exact same tread pattern, moulded in a compound soft enough you can literally twist a 'knobble' a quarter turn on itself with your fingers! May look like the 'klnoblies' they fitted as OE to bikes like the DT125 in the show-room, but that's only because of the regs, in the case of the DT for C&U and for trials in the hand-book.

As to 'knoblies' I suspect your idea of what may be one is probably also little errant; BUT see above, they are designed so that bludy great spikes of rubber 'dig in' to a soft surface and provide traction through that actual physical/mechanical interface, not friction.

They don't work very well on a hard surface where they cant do that, or on a surface that's either very shallow or very loose, like say sand, where they wont find enough purchase to dig and and drive, just dig in.... More agressive block-treads, or duel-purpose tyres, really just AREN'T knoblies... or work in the same way, or on such veriety of alternative surfaces, hard or loose.

One of the reasons for the trials 'slick' is actually to cover the greatest veriety of surface with a single tyre; from hard rocks, to moss covered bolders, to shale or sandy stream beds, often with the stream still in them, through peat and bog and clay, wet or dry, all the way to tarmac... where they do still work pretty well, actually, though tread-creep and the blocks bending when you lean at any speed can be a little disconcerting...... they just dont last many miles yards!!!!!

But if you want to ponder the anomalies, consider why, in road racing, where a on a hard tarmac surface a sticky 'slick' tyre, of any size is always preffered for maxiumum traction, why, in the wet they actually use a hot poker to cut relief grooves in the things and give them a tread pattern!?! And still often use narrower section tyres to stilletto through the surface water better. Regs would let them use a wide, untreaded slick if they were daft enough, and there have been enough GP's where riders have... often because they have usually wrongly predicted a short shower and drying track, and guessed an advantage as rain stops and track starts to dry, or been out in the rain, on full-slicks, and made the decission not to loose extra time coming in for an 'early' or probably an 'extra' tyre change, but man-it-out on what they are wearing.

Which is all more 'chaff'... what is used or done in practice, for various reasons isn't always, and in fact can rarely be, what is predicted as the 'ideal' by the science.... but that doesn't make the science 'wrong'. The science is the science, and the laws of motion the laws of motion... A-N-D what we always get back to, is that for ALL the various variables in applying that science, first ultimate grip is by far and away most significantly effected by how soft the tyres is.. next, the money-men almost always get the last say, not the wingineers!
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ThatDippyTwat
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PostPosted: 18:35 - 04 Mar 2018    Post subject: Reply with quote

Teflon-Mike wrote:
What about them? Its a very artificial class, to start with, picking a highly specialised dirt bike, and trying to mod it for road use, then find a course that the resultant mule favours!


Go ride one, in anger, then come back and talk. It's a whole different world. Wink

Just because they didn't have them back when you were pretending to be an instructor, or you know fuck all about them, doesn't mean they're shit.
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Teflon-Mike
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PostPosted: 19:11 - 04 Mar 2018    Post subject: Reply with quote

Lol! We were muggering about with the things back in the early 90's when I was still at college!
One mate had a road-legal CR250 with TZ wheels, after bending a bus with a VT500, and reckoned it was a lot easier on his broken back!
Another had a Miaco 'Bitza' created with a lot of left over Triumph bits, cos they wouldn't give him the miles to ride home to Somerset on a 'classic' policy for his trumpet.
Meanwhile I never said they were shit, or they weren't 'fun'... just an anathma, with a race class created arse about face to suit the mutant special, rather than a bike actually designed for competitive advantage....
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M.C
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PostPosted: 19:41 - 04 Mar 2018    Post subject: Reply with quote

ThatDippyTwat wrote:
M.C wrote:
Forgive me if I don't trust BCF logic (can't hear loud exhausts when they're behind you etc.).


They echo, the sound is reflected off buildings etc. Deeper notes are better heard than higher ones, and typically free flowing cans will ahve a deeper note.

The BCF scientists say they only project sound backwards Folded arms

Teflon-Mike wrote:
a quarter turn

How many?

Teflon-Mike wrote:
But if you want to ponder the anomalies, consider why, in road racing, where a on a hard tarmac surface a sticky 'slick' tyre, of any size is always preffered for maxiumum traction, why, in the wet they actually use a hot poker to cut relief grooves in the things and give them a tread pattern!?! And still often use narrower section tyres to stilletto through the surface water better. Regs would let them use a wide, untreaded slick if they were daft enough, and there have been enough GP's where riders have... often because they have usually wrongly predicted a short shower and drying track, and guessed an advantage as rain stops and track starts to dry, or been out in the rain, on full-slicks, and made the decission not to loose extra time coming in for an 'early' or probably an 'extra' tyre change, but man-it-out on what they are wearing.

Which is all more 'chaff'... what is used or done in practice, for various reasons isn't always, and in fact can rarely be, what is predicted as the 'ideal' by the science.... but that doesn't make the science 'wrong'. The science is the science, and the laws of motion the laws of motion... A-N-D what we always get back to, is that for ALL the various variables in applying that science, first ultimate grip is by far and away most significantly effected by how soft the tyres is.. next, the money-men almost always get the last say, not the wingineers!

The grooves are for clearing water? Confused You use the correct tyre for the job, except it seems in this instance.
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redeem ouzzer
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PostPosted: 21:41 - 04 Mar 2018    Post subject: Reply with quote

Teflon-Mike wrote:

Meanwhile I never said they were shit, or they weren't 'fun'... just an anathma, with a race class created arse about face to suit the mutant special, rather than a bike actually designed for competitive advantage....


But they do have an advantage, certainly in lower speed situations, where the short gearing, light weight and wide bars help them out corner the typical race rep type bike. It's a fairly small window of advantage granted, but it does exist (the extent of the advantage depends on the powerplant, being that the term supermoto seems to cover everything from a DTR 125 through converted MX bikes and even big V-Twins). I've been stalked by a converted CR250 on a track day and it took much bravery and use of the straight bits to break the tow.
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pikey666
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PostPosted: 01:34 - 05 Mar 2018    Post subject: Reply with quote

[quote="Teflon-Mike"]
M.C wrote:

Seriously, a pretty average clubman push bike racer, weighs in at something like 80Kg; the actual bike adding about as much as a 'family' size bag of snax! And on a dyno, they can record a 'sustained' power-output more than a moped engine... 3bhp or so..... and for what they would term 'briefly' as in a mock 'break' or sprint, lasting maybe five minutes, as much as 8-10bhp.... And they put that sort of power to the road through tyres that are a mere 10mm in cross section, and perhaps only 2-3mm thick on the crest! They have to pump the things up to three figure psi's to stop the rider's weight crushing them on such a tiny contact patch, measured in square mm rather than square inches!


standard nonsense.

1hp is approx 745 watts.

chris froome as a tour de france winner has a sustained power output (called ftp in cycling terms) of 419 watts or just over half a hp.

https://www.cyclist.co.uk/news/691/chris-froome-s-numbers-what-do-they-really-mean

In an interview with Cycle Sport, mark Cavendish said he puts out over 1500 watts of power (about 2hp) in a sprint but would not be able to do that after a 200 kilometres race.

https://bicycles.stackexchange.com/questions/21294/when-mark-cavendish-says-hes-sprints-at-1500-watts-how-long-is-that-for

these figures are well above the average clubman.

also most race bike use 23 or 25mm wide tyres.

unsubstantiated regurgitation of pseudo facts make everyone look dumb.

Wub


Last edited by pikey666 on 21:35 - 05 Mar 2018; edited 2 times in total
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M.C
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PostPosted: 03:03 - 05 Mar 2018    Post subject: Reply with quote

^for the love of god fix your quotes Razz
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Baffler186
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PostPosted: 10:16 - 05 Mar 2018    Post subject: Reply with quote

Mephysto wrote:
I’m kinda drawn at present between the Yzf and mt
IMO the YZFR125 looks silly, it is styled around a race bike but that's a bit like styling a Ford Fiesta to look like an F1 car. There is also a lot of fairing to be scratched or broken if you drop it. The MT looks nice, and doesn't look to be trying too hard to look anything other than what it is.

That said, even a used MT will be more expensive, but if those are the boundaries you are sticking to then I'd certainly pick the MT
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pikey666
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PostPosted: 12:09 - 05 Mar 2018    Post subject: Reply with quote

M.C wrote:
^for the love of god fix your quotes Razz


Laughing

fixed, i'm so used to the tefisims that i didn't even notice.
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ThatDippyTwat
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PostPosted: 14:39 - 05 Mar 2018    Post subject: Reply with quote

Teflon-Mike wrote:
...blatherings...


The way you write/waffle makes it seem you have a very dim and dismissive view of them. As long as you can't out-gun it, they will stick to you like shit on a blanket, no matter if you're on the Latest Ducati V4 or a strung out IL4. I'm sure it was you that pointed out, in a long spergy waffle-fest, that 'they' created racing classes for the 600's which were not eligible for existing classes, so why is SM so wrong for doing the same? They're fun, people want to ride and race them, so manufacturers, tracks etc all accommodate that.

While I'm a little further away from deaths door than you, I was pissing around with KX500's on the road around say '95-'99ish, and mates had a variety of interesting kit (70's Bultaco springs to mind - it's road wheels cost more than my KX500). One mate still hoons around on a Maico 700 I have to resist buying every time I see it. I really want a play on one of the Husky 701's. I like them so much, I'm even debating the older MT-03 because I like a thumpy single, even though it's not a SM 'styled' bike.

It should be noted, we're talking "proper" SM, not cack factory look-alike's that are punted out to the kids.
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Freddyfruitba...
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PostPosted: 14:54 - 05 Mar 2018    Post subject: Reply with quote

pikey666 wrote:
M.C wrote:
^for the love of god fix your quotes Razz
fixed, i'm so used to the tefisims that i didn't even notice.

Nope not yet...
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Mephysto
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PostPosted: 15:38 - 05 Mar 2018    Post subject: Reply with quote

[quote="Baffler186"][quote="Mephysto"]I’m kinda drawn at present between the Yzf and mt [/quote] IMO the YZFR125 looks silly, it is styled around a race bike but that's a bit like styling a Ford Fiesta to look like an F1 car. There is also a lot of fairing to be scratched or broken if you drop it. The MT looks nice, and doesn't look to be trying too hard to look anything other than what it is.

That said, even a used MT will be more expensive, but if those are the boundaries you are sticking to then I'd certainly pick the MT[/quote]

Yea I’ve defunately decided against either of those thanks to the guidance of forum members, I don’t like the ybr though, never enjoyed the cbt on it,might be for other reasons like trying to o remember everything and having the instructor chirping in ur ear whilst trying to get to 60 in a decent wind, as yet I’m undecided but am looking at the not showily flash crap that’s probably been ridden wrong but hasn’t lived long enough to tell you how bad.
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M.C
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PostPosted: 15:40 - 05 Mar 2018    Post subject: Reply with quote

Baffler186 wrote:
IMO the YZFR125 looks silly, it is styled around a race bike but that's a bit like styling a Ford Fiesta to look like an F1 car. There is also a lot of fairing to be scratched or broken if you drop it.

That's what I find hilarious, the gap between the fairing and the frame, you can fit your whole arm down there Smile
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GSTEEL32
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PostPosted: 15:51 - 05 Mar 2018    Post subject: Reply with quote

Mephysto wrote:
Yea I’ve defunately decided .... thanks to the guidance of forum members


For the love of God, Nooooooooooooooo..........
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Mephysto
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PostPosted: 21:08 - 05 Mar 2018    Post subject: Reply with quote

[quote="GSTEEL32"][quote="Mephysto"]Yea I’ve defunately decided .... thanks to the guidance of forum members[/quote]

For the love of God, Nooooooooooooooo..........[/quote]


Just decided not to go for the boy racer thrashed bikes not which one I will go to relax bro.
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ThatDippyTwat
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PostPosted: 22:59 - 05 Mar 2018    Post subject: Reply with quote

Go ride a non-thrashed YBR before you discount a good slice of suitable, used, affordable bikes based on riding a fucked, thrashed, training school YBR a grand total of once. You may be pleasantly surprised. It's miles better than the CG.
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M.C
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PostPosted: 23:33 - 05 Mar 2018    Post subject: Reply with quote

ThatDippyTwat wrote:
It's miles better than the CG.

How so (genuine question)?
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ThatDippyTwat
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PostPosted: 23:47 - 05 Mar 2018    Post subject: Reply with quote

M.C wrote:
ThatDippyTwat wrote:
It's miles better than the CG.

How so (genuine question)?


Far more confidence throwing an abused training school YBR into a corner than any CG, abused or not. A looked after YBR on decent tyres (Avon Streetrunners etc) is surprisingly fun to throw around corners.

I find it a bit more reliable, and easier to work on. All CG's I've worked on/had lose oil. Yet to meet a non-fucked YBR that loses any.

Aesthetics are personal, but I prefer them over the CG's very 80's look.

Lastly, but won't apply to everyone. - the CG is great for midgets. I've not been under 6' since i was 13.
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