ty 250 improvements

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Guy53
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Re: ty 250 improvements

Postby Guy53 » Wed Aug 29, 2012 9:27 am

Good lord.
I do not want to start a war but for the second time this friday I attended a class on how to ride a TS and the first point was the riding position to make sure NOT to load the fornt wheel. I certanely won't go to a trial with section made by you FM.
Guy



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Re: ty 250 improvements

Postby David Lahey » Wed Aug 29, 2012 10:21 am

I just did some calcs using that table that FM350 provided a link for. I'm guessing that FM350 is looking at the unladen weight balance in that table for his theory about front end loading but bikes are not able to ride themselves so I worked out the load on the front wheel with a 180 pound rider aboard for the 2003 GasGas, TY250 mono and TY250 twinshock, using moments about the rear axle for bike weight and rider weight, assuming all the riders weight is applied to the footpegs (just like we are taught to ride).
Gas Gas 0.513x150+180x17/53=134 pounds
TY250 mono 0.468x184+180x14.25/52.25=135 pounds
TY250 TS 0.45x201+180x15.5/52.5=143 pounds
So the oldest design has the most weight on the front end, and the TY250 mono has slightly more than the 2003 Gas Gas
Maybe a different explanation might be required for why modern bikes are easier to ride (rather than front wheel loading).
I think the main contributing factors are improved mass centralisation and reduced weight.


relax, nothing is under control

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Re: ty 250 improvements

Postby FM350 » Wed Aug 29, 2012 5:07 pm

David Lahey wrote:I just did some calcs using that table that FM350 provided a link for. I'm guessing that FM350 is looking at the unladen weight balance in that table for his theory about front end loading but bikes are not able to ride themselves so I worked out the load on the front wheel with a 180 pound rider aboard for the 2003 GasGas, TY250 mono and TY250 twinshock, using moments about the rear axle for bike weight and rider weight, assuming all the riders weight is applied to the footpegs (just like we are taught to ride).
Gas Gas 0.513x150+180x17/53=134 pounds
TY250 mono 0.468x184+180x14.25/52.25=135 pounds
TY250 TS 0.45x201+180x15.5/52.5=143 pounds
So the oldest design has the most weight on the front end, and the TY250 mono has slightly more than the 2003 Gas Gas
Maybe a different explanation might be required for why modern bikes are easier to ride (rather than front wheel loading).
I think the main contributing factors are improved mass centralisation and reduced weight.



I guess you have never tried altering the steering angle on an older bike? The vast improvements to be found here come from increasing front wheel grip, by moving the front wheel spindle closer to the crank centre line. As motorcycle tyres have improved over the years, steering angles have gradually become steeper, mainly in order to increase front end traction and improve steering. Some very interesting information on steering geometry can be found in Tony Foales excellent book covering motorcycle chassis design.



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Re: ty 250 improvements

Postby FM350 » Wed Aug 29, 2012 5:14 pm

Guy53 wrote:Good lord.
I do not want to start a war but for the second time this friday I attended a class on how to ride a TS and the first point was the riding position to make sure NOT to load the fornt wheel. I certanely won't go to a trial with section made by you FM.
Guy



Try riding a tight and very slippery turn with all your weight over the back end of the bike (as you have been taught) and then give it a go with weight over the front to provide more traction.



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Re: ty 250 improvements

Postby David Lahey » Wed Aug 29, 2012 6:19 pm

FM350, have you ever ridden a trials bike in a trials section?


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whitehillbilly
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Re: ty 250 improvements

Postby whitehillbilly » Wed Aug 29, 2012 6:41 pm

How would we ever know David ???? someone on his laptop a million miles away, as we can all read anything that out there. At least we can see photos of you at Trials.

whitehillbilly



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Re: ty 250 improvements

Postby FM350 » Wed Aug 29, 2012 7:12 pm

David Lahey wrote:FM350, have you ever ridden a trials bike in a trials section?



I have been riding since the early 70s, and always find first hand experience counts for quite a lot. On very easy sections though I wouldnt expect old style weight distribution, and steering geometry are going to make much difference though. Updates to these areas do make a great deal of difference when riding sections intended for modern bikes though, and tend to make older bikes easier and more fun to ride.



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Re: ty 250 improvements

Postby Guy53 » Wed Aug 29, 2012 7:48 pm

Maybe the fact that I never go to a trial comp organise by a modern bike association ( even if they advertise that TS are welcome ) make me think differently from you FM. I am cheering for every organiser that promote non-stop trial, probably because that's the way I learned or because I simply like it when my fellow riders look and talk to me as if I was a good friend and not as if I was an old fool hoocked on the early seventy. Ho! no I won't try your tight slipery corner with weight on the front wheel, my dental work ( including my gold tooth like in the early 70 ) cost to much money.

GUy



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Re: ty 250 improvements

Postby FM350 » Wed Aug 29, 2012 9:22 pm

Like it or not if you try making a very tight turn on a slippery surface, or want more precise control in more difficult conditions, the increased front wheel grip provided by more modern machine lay out, will work far better than the older style bike set up, which was designed to work with rear tyres which didnt grip very well.



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Re: ty 250 improvements

Postby Jon V8 » Wed Aug 29, 2012 9:54 pm

I can confirm that Chris does actually ride trials,though I have never seen him finish one.I may be alone,though in not having front wheel grip problems on any of my bikes which range from a 1950 rigid AJS to my "newest" bike a 1979 Ty175 with the Serow engine in it.They all have perished or worn or both front tyres.Strangely enough the rear tyres are all new/nearly new IRC's.The trials I rode back in the mid eighties were far harder than the stuff we do now,but the TY250R I had was never wanting - it was my ability/confidence that let it down...
PS, Guy - my Majesty project is on hold at the moment as I'm concentrating on riding trials for a while,rather than building bikes.Plus going on holiday. :wink:




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