why light wheels make your bike turn easier

Hobot, with a road racer it always pays to go fast slowly, and work up to speed. Practice makes perfect.

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I suspect about everyone but me picked up a Norton on purpose then worked up skills. Not me first ever Norton ride wheelied me like a flag off bars to end in perfect locked up frame side slide like a stunter bounced up right on curb infront of houses. totally expecting to die the whole time. Got ok on handling the power after that but never could learn leaning on the dragster. Then landed in Ozarks to crash every ride for days and often afterwards just making it to terra firma. No creeping up on it so finally went bezerk to tackle THE Gravel then moved on to tarmac and a corner school I found limits of normal handling then made myself do what I came to, NAIL it it knowing it was going to really break loose at high speed but not what would happen after. Similar to just tooling along safe rate on THE Gravel and front rolls up a walnut size stone the rear hits like a marble, Bingo flat tracker stunt rider clown act on surface that now acts like snot. Some energy barriers ya can't tip toe across but must freaking commit to the leap. I repeat even though I got to take on the local squids with Suvee no way can I get her powered up to set up to even practice Peel's entries let alone the higher loads the rest the way around. I repeat watching elite racers is counter productive and all I can see it how limited their cycles are and how I'd go around them this way or that as there is no perfect line on a totally neutral handling cycle as long as torque enough on tap to over come tire or bike mass reaction.

Past Peel was at least 50 lb lighter than started out but same steel rims and heavy dual purpose tires/tubes that may of added to the fork twist/rubber band connection action-reaction delays. But that resolved with RGM fork brace after turmoil to fit right was well worth it. So what would lighter wheels do for Peel? They ain't all that lighter any way compared to what's been shown and done before. Peel never slipped w/o intending nor twitched even though I tried to find a way to induce it. Could crank over sharper and sharper on more and more power till she had all mass on rear and pulled sideways wheelie out of a peg sctaching lean angle, draining blood out of vision too. Could go in even faster and trade one direction speed for another by over power rear at next to last instant from edge of road so whole bike mostly side ways to motion would hook at last instant to fling up off surface like a sling shot in the right direct to smash patch down to take even more power out of there. No more throttle cut than to snick a speed shift, which Peel would do in mid turns running out of rpm. I just ain't got much respect for cycles that scare me or hurt others attempting this.

Would Peel break free easier or take longer to hook back up with lighter wheels? Could I flick forks faster with lighter wheels? As it was I just let the bars tank slap one half cycle on their own way faster harder than I could move em myself. Would I be able to fling Peel over faster with lighter tires? As It was in some turns I was powering up so harsh where everyone else on brakes she instantly trip out on a slight tip for rear spin to a peg foul then I'd pick back up so rear'd hook up a leap forward and repeat a few times till corner cleared and solo rest of the way. Would Peel fly further or less far side ways on a phase 4 leap? Would she wind up frame tighter to fly higher than expected with lighter wheels? Will I tear the spokes out so have to go with a cast wheel? Will lighter wheel tend to spin tire or bead more on drag launches? Will lighter wheels be more scary on THE Gravel?

hobot said:

Sorry to say Al but a straight perfect made Commando only helps to assemble easier and isolate sooner not much help to its innate floppy eared scary handling. .........Peel's frame was about dead on, and the mis-manufacture of engine surfaces squared to each other too but still ran into THE Hinge w/o the rump rod, the top and front links helped smooth the ride sense but did not stop the wobble/weave onset at some point. Believe me or not i'm not the one missing out but have no more concerns worries or thoughts to better handling -beyond the dangerous unpredictable moderns- so just lightening up and adding MO Power to have more fun faster. I've had pow wow's with Ken Augustine and he told me his process to sharpen up Cdo handling involved shortening the wheel base by taking up the space between engine and tranny, which surprised his race riders and the competition, but of course ran out of hp in the wide opens.........

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Hi hobot,

If yourself and others still insist on using the spine tube as a datum then, sorry, but your methods are flawed, which is backed up by your on-road experiences re 'hinged in the middle' handling. My bike did have these traits, although the bikes are not hinged in the middle, it may feel like they are but the problem is the relationship between rear wheel and swing arm pivot, swingarm pivot to steering head axis and rear and front wheel to frame CL. Once all this is checked accurately, the only way I can think of is using a surface table, and corrected as required, then, believe me, the bikes steer and handle.

I checked a NOC members frame front and rear iso mounts, which were out, no surprise, but I said they could be corrected as first step of alignment. He decided to take the frame home, did some welding, got most of the way to completely assembling the bike, and then noticed some things didn't look right. Using various methods advocated on this forum (but no surface table) decided the frame was bent, as in had been crashed at sometime in it's life.

A second frame was purchased, again using alignment methods advocated on this forum, but no surface table, concluded the frame was straight. Everything went together. He's happy the wheels are in line. Running up a straight motorway at 75mph the bike breaks into a weave.

Do your bike and yourself a big favour and get the frame blue printed. It is well worth the effort and you only have to do it once. I'll be eternally grateful to Stevan Thomas http://www.vintagenet.us/phantom/wsc for his words of wisdom. You will be too if you get the work done.

Ok Al, I sure can't contest your experience nor wisdom to have everything as true as can be. I have not had straight line riding issues on mine only on lumpy, gusty turns going fairly fast and then mostly onset from old stiff tires. I've only done enough frame corrections to get stuff to mostly fit with the size hammers and levers and helper on hand and some heady steady shims still needed. On my still tweaked Trixie Combat, found I can run with the most expensive elites out there for a joy ride in Mt. roads w/o weave/wobble up to the speeds they were comfortable with, though was nerve wracking to stay just short of weave-wobble onset, which i think is innate on all un-tamed-tri-linked Cdo's. I only run into un-tamed Cdo upset when I try to ride for some corner thrills into rough &/or gusty turns. On nice smooth slightly banked turns I have pressed Trixie a number of times into rear tire step outs on hi throttle in 2nd or 3rd gear 70's to 90's mph w/o upset but a scary twitch to let me know that's the limit to avoid. What confuses me also is the long rides done on 2 Combats with fractured axles in Mt's and city traffic and freeway yet only got upset till speed over 5-6 mph then felt fine even hands off testing but just stayed with traffic flow not pressing turns any harder than needed to steer normal.

To stay on subject I wunder if lighter wheels would aggravate frame mis-alignments upsets or help avoid it.

Ken, the larger rake and trail geometry gives stability, however too much can cause the bike to stand up and turn the wrong way under brakes. I always use the TZ350 Yamaha as a bench mark. It has 26 degree head angle and about 35mm of yoke offset with 18 inch wheels. With a peaky motor, it will easily step out and high side you. My bike has 27 degree head angle and TZ350 fork yokes. It stays stable under brakes, and self-steers in the correct direction under power when laid over coming out of corners. I think that if I had a top end motor, it would easily highside. I've ridden very nasty bikes in my life, and when I ride I try always to be super smooth. If you gas my Seeley 850 hard coming out of corners, the motor is fairly gentle but fast in its power delivery, so the back end doesn't step out. I suggest a lot depends on the nature of the power band and gearing, as to what steering geometry can be safely used. I believe my bike is currently close to the safe limit and it really suits my riding style.

If I need to brake in a turn then I'm ashamed of myself for going in too fast so make dam sure ALL my brake use is upright-inline ahead of any leaning or tend to slip down or fly up unintended. I still have an open mind on wheel mass [after open wounds] so likely a Goodlie Locks compromise depending on the scope of what the pilot aims wheels at to deal with. Part of Peel's rub is how much performance [any way measured] can be gotten out of essenitally vintage technology, like spoked rims, on and off road. Here's more food for thot from bicyclers...

WHERE IS THE WEIGHT?
There are places on a bike where weight has a greater effect on performance and handling. Stout and heavy hubs have very little effect on how a bike feels. Their weight is low on the bike and at the center of the wheel. Weight on the wheels that is not rotational (at the outside of the wheel) is not as noticed when the bike is in motion. The reason disc brakes do not seem to detract from the bike's performance, even though they are quite a bit heavier, is that they are at the center of the wheel, not up on the bike's frame. Rims are at the outer edge of rotational weight, so they have a much more serious effect on accelleration. A heavy saddle or tools inside of a seat tube mounted pack cause the bike to resist subtle weight shifts during cornering or while making quick moves around and over obstacles. Weight that is carried low is always prefered to weight carried high. Weight at the center of the wheel is always prefered over weight at the outer edge. That said, a heavy rim and tire will make you much more stable when going fast over anything. The more the outer edge of the wheel weighs, the better the gyroscopic effect of the spinning wheel. To get a good picture of how important gyros are, grab your brakes while you are in the air on a jump and you will fall like a rock. If you let your wheel spin, your flight will be smooth, stable and controlled. The wind resistance of the tread also has great effect on this phenom. Of course, don't try this if you are not already a jumper. Using the spinning weight of a wheel is one of the more subtle skills in jumping. Grabbing the front brake means the front end falls. Grabbing the rear brake means the rear falls. If you ever get a chance to watch Robby Knevel in the middle of a huge jump, watch how he feathers the throttle to change the rate of his rear wheel gyro and in turn makes the front or the rear of the bike rise or fall.
http://www.dreambike.com/weight.htm

hobot said:

If I need to brake in a turn then I'm ashamed of myself for going in too fast so make dam sure ALL my brake use is upright-inline ahead of any leaning or tend to slip down or fly up unintended.

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Then you will be ashamed when you are passed. No winning there.

The quickest way around a corner on a road racer it is to brake down well into it to the maximum speed for the middle of the corner, and then get immediately back on the gas with minimum rolling distance in the middle of the corner. If the corner is a tight hairpin, it helps if your bike can maintain a high rolling speed in the middle of the corner. Skinny tyres and a light bike are better as long as you have enough grip. Have a look how this guy does it ;

http://www.youtube.com/watch?v=V3BHLRQTBts&noredirect=1

A bit off topic but it is called feather braking. Not sure how effective (or wise) it is with drum brakes but it works a treat with disk brakes.

Hehe, Dances come on out and try that leaning steering while feathery trail braking on THE Gravel. Can't bluff me on your lack of brake physics. I broke bones and bike learning and its one of the things a lighter front definitely helps any cycle on. I do chicken out when leaning and feathering brake on off slope Gravel turns so steep tire scratching ABS like so not locked up still don't slow bike from gaining speed, what do ya do then? If you are on a corner cripple then only straight lines can be taken fast so they then tippy toe around the turns braking on half the effective tire patch than upright. Its was the dominance of Ms Peel shooting past sluggish trail brakers or the even funnier ones using front brake and rear throttle at once!!! LOL> Consider the difference in sensation and sense of security being hard on throttle where all the good pilots on unstable bikes are haf-fast hard on brakes mostly trying not to fall over, sheeze. When ya get going fast enough tarmac gets as loose as THE Gravel then lecture me on how misguided I am. All the magazine testers and racer interviews always talk about how deep in they brake and how soon after apex they can get on power. Duh, After Apex?> what about the funner half of turn before that? Of course at some point swinging hi G's around turns can lift tire right off the surface. I like that and makes brakes completely useless to slow but helpful to turn in some conditions or save a low side if ya over do trail brake. If ya really must slow in middle of a turn or worse stop, best way is lock both brakes and sling bike sideways so both tires doing full duty.

hobot said:

When ya get going fast enough tarmac gets as loose as THE Gravel then lecture me on how misguided I am.

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That's easy - how misguided, very misguided. Lecture over.

hobot said:

All the magazine testers and racer interviews always talk about how deep in they brake and how soon after apex they can get on power.

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Otherwise known as feather braking.

hobot said:

Duh, After Apex?> .

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Well duh, certainly not before the apex, otherwise you were going too slow.

Think about it for a minute here. Your ripping along and get on the brakes and propose to get all your deceleration done before turn in yet you are not using up all your traction during turn in - what a waste. Keep on the brakes (feather braking) to load the front end to increase traction to facilitate turn in and reduce the effective head angle to further facilitate turn in. If you are off the brakes and initiate the turn without needing to feather brake you are going slower than you need to so all that time while you are turning in at a slower speed someone else will zip by you while decelerating towards the apex.

And not on THE gravel. Asphalt is not gravel - that will be my next lecture if you don't start making sense here.

And why were you not at Barber?

Oh gads zooks Dance, have I've gotten to enjoy your slapin's. The only times I've crashed trying to change direction has been on THE #^&* @vel and that was because I was being so wise, careful and slow to drag brake a bit >SPLAT SPLAT etc.
You and all the rest of the world my well be able to handle turns faster by braking effectively on leaned front tire edge pointed away from the turn direction, just not me ever again if in a hurry. Gave this some deep thought about Peel sticking with single rotor for less spun mass and my avoidance of leaned on braking for taking on track times and seeing if anyone can chase Peel around turns with a camera at Barbers. The G forces Peel delivered some years ago is still a constant high to me, not the moderns I've tried. If there is over 45' leans involved I don't ride like normals, but if only 45' or less then its not really a turn to me just a power to mass vs air drag contests handling hardly matters. I don't like to break free per say as that cuts the acceleration but some times its worth the hesitation to change directions w/o loss of momentum. I don't trust the front any more but to hold frame off ground if not lifting by engine power and slowing enough inline to get set up to let er rip on the tip over zoom around part. Homestead repairs like big tree taking down shed power line and door, slow work and long trip alone again in a cage with yuky weather just to get ganged up on at Barbar's, not this year. Big buck took out car lights and grill last week, as i'd slowed up so much on trail braking around a sharp down hill it was able to out leap car and got ahead of me then stopped to look and cock head at the horn sound WHUMP, 25 mph so didn't kill it and no pistol so it got up and away. If it'd just finished its last leap over the fence I was slow enough to miss.

hobot said:

To stay on subject I wunder if lighter wheels would aggravate frame mis-alignments upsets or help avoid it.

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Heavy wheels generate a larger gyroscopic force than lighter ones so on a smooth surface in a straight line they should contribute to a steadier ride. On a bumpy surface, with the swingarm axis not square to the steering head axis, then the rear wheels relation to the frame centre line is constantly changing and will set up a frequency as well as give the symptoms of worn swingarm bearings, which manifests it self as a weave. A heavier wheel will create a greater force again so requiring greater rider input in an attempt to control the bike. Not 100% sure of my technical terms but pretty sure this is what happens.

Dances with Shrapnel said:

Keep on the brakes (feather braking) to load the front end to increase traction to facilitate turn in and reduce the effective head angle to further facilitate turn in. If you are off the brakes and initiate the turn without needing to feather brake you are going slower than you need to so all that time while you are turning in at a slower speed someone else will zip by you while decelerating towards the apex.

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UK police and others advocate not loading the front end into and going through a corner. The reasoning is you want the front suspension to be able to do it's job as well as possible which it does best unloaded. So they recommend gripping the tank with your knees, to minimise body weight transfer under braking to suspension via the handlebars and holding the bars lightly. This reduces unwanted rider input a lets the steering and suspension get on with doing it's job as designed to. The rider should then accelerate through the bend to maintain speed.

Also if a tyre is already loaded due to breaking then there is less cornering grip, not more.

So does Ago do it correctly ?

I suggest there might be a balance to be maintained between wheel weight (gyro effect) and steering geometry (lightness and self-steering effect). If the bike self-steers the right way, you can get on the gas much earlier, at the risk of a high-side experience if you get careless. There was recently a magazine article on the MV3-500 Evoluzione which Ago was building and selling on for a big number. It mentioned that the fork yokes were made to Ago's preferred specification. Draw your own conclusions after watching that video clip I linked to in my earlier post. In most corners he is either braking or on the gas, never rolling.

A tyre has so much grip. There's a trade off between braking grip and cornering grip. The more you brake the less cornering grip is available and vice versa.

Bing-0 Al - I ride about like everyone else if just trying to commute somewhere with police and hazards all about, ie: I share - slit - divide and subtract tire traction loads as plenty to spare, like the racers demo lifting a rear entering on a counter steering front tire dependent turns - while rest of the pack piles up behind, so new race bunch starts about each good turn.

When I get in a hurry though I never ever *divide* split *subtract* tire vector loads, I Only Do One Thing At Once on a tire, pure brake in line, pure acceleration in line or pure rear thrust turning loads. The front is only thing with traction when I brake hard, the rear is only thing in traction when I accelerate and turn hard. By putting most or all the loads, bike/pilot/power mass, on one tire at a time it increases the traction on that tire above what can be had if still some load on the other. Patch gets rather bigger in these instants of spike loads too. Smooth riding is not the fastest way around unless stuck on rails, think ricochets off objects and the tank splapping low-hi side crash antics faster than a pilot can control -[ on corner cripples]. I've seen a few racers pull off some of this single tire turning loads, where front or rear gets air, but only in a few special places, while a good motorcyle allows it any where in any turn, if still enough power on tap.

Most exciting test proof on corner cripples for me was Kieth Code angry ordering a show down with his chief instructor who was already PISSED OFF pulling me off track to send me home but being told let me go out again by Code. So he took off w/o a word or warning heading for his X mark in what would be labeled a 35 mph sweeper turn in public, I hesitated an instant in shock but took off on my own line, skipping the rear out 3x's while hugging the curb to pop upright 3x's for 3 short inline drag sprints then shifted to 3rd to finish and ran to top of 3rd 13,000-14,000 rpm into the open, then covered brakes sat bolt upright and looked around to see where he was before I changed position on track in case he might run into me, Not a chance as saw him just finishing his apex way way behind. Then I slowed up to let him catch up as I was about to go too fast for his dual X apex chicane I turned into one apex in between the turns so both turns done in pure inline dragster mode. Just like I have to do on THE Gravel [marbles/arrowheads]. So up to 90 mph in the rear chrip outs faceting and 120 coming upright exiting. Peel could put more accelerating G's down which flabbergasted me no end. Ninja topped out mid 140's, Peel only mid 130's though.

Can't beat a light ray path around and out to facet turns...

So i think Peels Excel spoked rims should be light enough

Al-otment said:

Dances with Shrapnel said:

Keep on the brakes (feather braking) to load the front end to increase traction to facilitate turn in and reduce the effective head angle to further facilitate turn in. If you are off the brakes and initiate the turn without needing to feather brake you are going slower than you need to so all that time while you are turning in at a slower speed someone else will zip by you while decelerating towards the apex.

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UK police and others advocate not loading the front end into and going through a corner. The reasoning is you want the front suspension to be able to do it's job as well as possible which it does best unloaded. So they recommend gripping the tank with your knees, to minimise body weight transfer under braking to suspension via the handlebars and holding the bars lightly. This reduces unwanted rider input a lets the steering and suspension get on with doing it's job as designed to. The rider should then accelerate through the bend to maintain speed.

Also if a tyre is already loaded due to breaking then there is less cornering grip, not more.

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Then along your line of reasoning, all the very fast racers are doing it all wrong. The UK police recommendation is very quiant and makes some sense for street riding only in that it suggests conservative corner speeds. So was the UK police recommendation during the era of drum brakes or disk brakes, I think that would have a bearing on the context. The UK police probably do not advocate passing in a turn nor racing. Furthermore, road surfaces can be very unpredictable (THE gravel) whereas a closed circuit road course should more or less remain the same, lap after lap so THE gravel should be a non issue.

In most instances the turning in does not use up all your traction and loading the front wheel increases the traction available to turn in. I suppose if one has truely crap suspension where gross quantities of stiction are realized under braking then that is another matter. One example of where one can run out of traction when initiating a turn is coming over a rise hard on the throttle while needing to flick from one side to the other; it can get real interesting while the front wheel is in the air. There is a lot to the dynamics of the act of initiating the turn and maintaining the turn that is not readily evident without a little reading and experience.

I am not advocating that everyone should be using feather braking all the time but it is a skill that can save your skin on the street if used wisely. I recall this line of thought was covered on this board at least once before.

Alright DanceswithShrapnel,

Ideally, you get all your braking done before turning into the bend. If you go round a corner on a constant throttle you slow down, applying the front brake also slows you down and gives you less grip for cornering. As the bike is leaned into the corner then the throttle is smoothly opened to maintain speed or accelerate through and out of the corner as you wish.

It is current police recommendation on taking a corner as in the police 'Roadcraft' training manual. It dosen't matter if the bike has drum or disc brakes, or if it's for road or race, the same laws of physics still apply.

Fair enough Al-otment but what is good for the goose is good for the gander.

How is it ok to accelerate out of a turn (and use up traction) yet not ok to slow down through feather braking leading into the turn(and use up traction)? Your assertion seems inconsistent since the laws of physics still apply.

So is it easier to drag a locked wheel with 100 kg vertical load on it or 400 kg load on it? More front braking = more front loading = additional traction ...to a point.

Drum brakes to don't modulate well when compared to disk brakes; at least the ones I have used and the general rule on the track (for me) is to get all the heavy braking done before turn in with drum brakes unless I sense otherwise. Some drum brakes tend to be somewhat self actuating and are not amenable to feathering out when you need a light touch.

The whole point of feather braking is to:
Load the front wheel for additional traction to initiate the turn in.
Load the front suspension so it has additional travel to extend as the bike is flicking over about it's center of mass (front wheel needs to extend to reach the road surface as the bike "falls over").
Reduce the effective head angle to facilitate a quicker turn in, and
take advantage of so many meters (ft) of distance to decelerate rather than putter/roll through a turn.

The concept is to be off the brake when you need maximum traction while in the turn; that's where feathering out the braking comes in. If you have not done it then it may be difficult to understand.

The current police recommendations cited are most likely for street use. As I stated earlier, it is not to be used by someone who does not have a sense of feather braking nor the skills nor experience.