Front Tire size vs braking ability

Hobot · May 20, 2012

After I poked a big hole in fluid resistance in Trixie's front brake and cleaned the surfaces I've having worries about locking up over 60's. Last year didn't go that fast on hard old tire to need much brake but this year on fresh meats and familiar with quirks and limits - seems too easy to squeal to loud over 60. I'm pondering next front in 110 instead of 100. Peel had 110's on front that seem more effective but also had re-sleeved master cylinder and race lever and hollowed out rotor. No way Trixie can brake like Peel but now Trixie has power enough, maybe one tire size up really helps the Whoa. Pretty dang happy with factory brake in my un-tamed Cdo I tell ya, but not guts enough yet on un-tammed Trixie to practice locks up to avoid. I was swayed last year by reports of easier handling with 100, well not that I can tell, but for more scary noise slowing in time. Don't get me wrong I try to lock up on many final stops at home but thats only a few mph with feet out. Traction theoretically should be the same with tires this close, as similar patch area per air pressure with bike mass. So what have other noticed?

pete.v · May 21, 2012

Any tire and brake system will lock up on gravel.

However, I have found that if I can get any tire to lock up with funky ass stock brakes, I am doing great, particularly the rear. After market has solved the front disc issue, rear shoes (even good one) are still iffy.

But then again, you are asking quantum related questions to the general Norton public. You really need to find out what forum Steven Hawkings is on to sort out your issues. You are waaaaaaaaaayyyyyy beyond scope here

Hobot · May 21, 2012

OH UGh, Don't Never Ever Again use words Brake and Gravel in the same sentence when communing with me. Either you go slow enough you don't need much of them or Man up to hit something or go down. But it has given me less of ham fisted sense - so much so if my conscious mind grips the level in panic my subconscious makes palm burn like a Red HOT Rod Witch test = so just as instantly completely let go. Only times I've ever crashed turning was already going pretty boring slow and added a tiny bit of brake while tire not perfectly in line with real blot upright. I never ever trail brake for most a decade now always enter w/o need of it so leave that to the experts. Straight line braking is all I'll do or just throw the dang bike down sideways, hoping not to get run over like another recent dead bike out here.

I removed the restriction on otherwise factory brake to be very pleased and with new-ish tires on and a year of working up to fouling limits and relearning untammed-unlinked wobble weave avoidance I've picked up my pace in the nice spots to get more noise before stray dogs, people edging up to road or just sharp 20 mph turns at end of long downhills or good pavement. Will see if google knows where Hawkins hangs out.

You do reveal some deep insights yourself mentioning the quantum level indeterminacy - uncertainly principles of electron-photon energy clouds interaction at their inter face.

I've done some instants of lock up over 60 on Trixie but that's more to test my bravery and brake power than actually pulling down as fast a possible. IN the end will just have to put 110 on and see for myself but would be healing inside to talk with someone that got some wits on this already. Its made me pensive I shot Peel in front foot with her new 100 Avon, which if does lower brake ability Trixie will inherit it and Peel gets a new 110.

Hobot · May 21, 2012

Ok you got me good on your lead, just like us local like to guide the tourists, hehehe, Looked up Hawkins and motorcycles so innocently to find the astrophysics I'm long familiar with and maybe a bit ahead of with the lesions learned on THE Gravel travel. My swamis and yogi Guru's know it all boils down to pure magic in the end after ya get bored counting turtles on turtles all within turtles shells of event horizon projecting reality as 3D hologram. Btw Steven is also a medical mystery I've learned the hard way too. he should of been dead a long time ago, but for his brain intelligence and will power to over come the physics of his disease, seriously look it up.

I'll leave you some my insights on my crazy moods last decade coming to identical conclusions as Hawkins...

So what does it mean that Hawking, who is arguably the Einstein of our era, is recommending a "Great Escape?" That he's saying we've doomed the planet and that we better find a way to live in space - SOON - if the human species is to survive?
Well, it probably means that we're doomed.

montelatici · May 21, 2012

hobot said:
After I poked a big hole in fluid resistance in Trixie's front brake and cleaned the surfaces I've having worries about locking up over 60's. Last year didn't go that fast on hard old tire to need much brake but this year on fresh meats and familiar with quirks and limits - seems too easy to squeal to loud over 60. I'm pondering next front in 110 instead of 100. Peel had 110's on front that seem more effective but also had re-sleeved master cylinder and race lever and hollowed out rotor. No way Trixie can brake like Peel but now Trixie has power enough, maybe one tire size up really helps the Whoa. Pretty dang happy with factory brake in my un-tamed Cdo I tell ya, but not guts enough yet on un-tammed Trixie to practice locks up to avoid. I was swayed last year by reports of easier handling with 100, well not that I can tell, but for more scary noise slowing in time. Don't get me wrong I try to lock up on many final stops at home but thats only a few mph with feet out. Traction theoretically should be the same with tires this close, as similar patch area per air pressure with bike mass. So what have other noticed?

With all the weight transfer to the front wheel, on dry tarmac in a straight line with half decent rubber, with even the most optimized stock front single rotor disc, it would be very difficult to lock up the front wheel I would think. I don't think tire size would make much difference, smaller effective cross section under braking of the thinner tire would present just a little less surface area with a little more pressure on that slightly smaller patch area. Rear brake is a different story, even with the drum. Many, like myself, don't use the rear brake for street riding.

Hobot · May 21, 2012

With all the weight transfer to the front wheel, on dry tarmac in a straight line with half decent rubber, with even the most optimized stock front single rotor disc, it would be very difficult to lock up the front wheel I would think. I don't think tire size would make much difference, smaller effective cross section under braking of the thinner tire would present just a little less surface area with a little more pressure on that slightly smaller patch area. Rear brake is a different story, even with the drum. Many, like myself, don't use the rear brake for street riding.

montelatici That is exactly how I thought I understood it and may turn out to just so, ie: I've about hit limits of regular Commando no matter what tire on front. I'm a bit of a Tribology student so know surface area ain't really what matter most. Over 70 Trixie front is ABS like but below that I've locked it an instant now and then tasting traction before the need of it. Tire was pretty warm on Satrudays joy ride but not hot. Not sure I can run a regular Cdo get hot tires anyway w/o letting most the air out.

When I first got Trixie I was surprised by her rear brake ability to lock up at 30+ mph on tarmac. I found when rear locked at 30-ish you can steer a skewed path using straight steer like in a parking lot. After deer strike I rebuilt wheels and can't get rear lock up power again. I know what each brake is best used for and Trixie front stopping is still good enough to unload the rear brake effectiveness on hwys.
I don't seem to get dive enough to bother me or her thank goodness.

montelatici · May 22, 2012

I should probably explain that I have the front and rear CNW Brembo brakes on my Norton with the floating discs and the rear will lock up with the tiniest of taps (so it goes unused outside city traffic at slow speeds). The front, as powerful takes a handful to lock it up. In fact, with the single Brembo, it is possible to do sportbike style stoppies (locking the front) but it takes some concentration. So it is my contention that before you will lock up and slide the front tire, it would be more probable that you would flip over if the front brake was truly powerful enough!

xbacksideslider · May 22, 2012

Tire air pressure has a lot to do with it too.

I try to find a pressure that high enough to ensure stability in high speed transitions yet soft enough to increase the area of the contact patch under braking to the point short of squirming under hard braking. Lower tire pressures also alleviate deficiencies in your suspension, again, short of loss of high speed stability. Then too lower pressures speed tire warm up. Yeah, tire mileage goes down some, its lousy already.

Hobot · May 22, 2012

I don't believe a normal un linked Commando can do a stoppie beyond barely lifting rear out of traction and maybe an inch just before complete stop, as the isolastic frame won't stay centered enough for pilot to prevent it swooping ends. Any more brake power applied will lock the tire and slip w/o stoppie.

My inquiry has nothing to do with lack of brake power but the opposite, more brake power than I can get tire to hold. Remember I live on THE Gravel so feathering brake for best slowing w/o lock up is only way I can make it routinely on slopes with sharp bends and hazards. I get scared when I hear loud Gravel scratching sounds or loud tarmac squeals. I scream sometimes when so steep loose I can't use front brake as just locks and rolls off tops of rocks so only engine drag and rear brake work, after not starting down too fast first.

I run 28 PSI rear and 26 front mostly to stand the jarring off pavement, its plenty soft to smash down wider patch compared to the PSI most others brake on. Its about as soft aired to still allow good power leans on pavement, much lower and tires distort and tend to wallow on power leans, which onsets THE Slap and THE Hinge.

Ugh to know what works best for me, will have to keep slowing up more ahead of time - till front changed back to a 110. Not that big a deal as I don't risk maxing out on a factory Combat. But sometimes one ain't got a choice, stop fast right now or smack!

montelatici · May 23, 2012

hobot said:
I don't believe a normal un linked Commando can do a stoppie beyond barely lifting rear out of traction and maybe an inch just before complete stop, as the isolastic frame won't stay centered enough for pilot to prevent it swooping ends. Any more brake power applied will lock the tire and slip w/o stoppie.

My inquiry has nothing to do with lack of brake power but the opposite, more brake power than I can get tire to hold. Remember I live on THE Gravel so feathering brake for best slowing w/o lock up is only way I can make it routinely on slopes with sharp bends and hazards. I get scared when I hear loud Gravel scratching sounds or loud tarmac squeals. I scream sometimes when so steep loose I can't use front brake as just locks and rolls off tops of rocks so only engine drag and rear brake work, after not starting down too fast first.

I run 28 PSI rear and 26 front mostly to stand the jarring off pavement, its plenty soft to smash down wider patch compared to the PSI most others brake on. Its about as soft aired to still allow good power leans on pavement, much lower and tires distort and tend to wallow on power leans, which onsets THE Slap and THE Hinge.

Ugh to know what works best for me, will have to keep slowing up more ahead of time - till front changed back to a 110. Not that big a deal as I don't risk maxing out on a factory Combat. But sometimes one ain't got a choice, stop fast right now or smack!

I never tried to do a stoppie when I had the stock front disk brake, the thought never crossed my mind, but I don't think the stock brake will do a stoppie at all, but I don't think it will slide either. On tarmac that is.

Hobot · May 23, 2012

Dude I live in another orbit of Commando performance and that includes brake power on un-restricted Lockheed factory brake or Ms Peels re-sleeved 13 mm brake. Braking is the most important thing to me and force myself into working up panic attacks with locked front tire both on factory and up-graded brake power. I have full lock up on tap by either brake below 60 mph on 100 to 110 tires, brake power may limit everyone else but not me, I've no worries on power enough to lock up, its the dang surface and tire grip that I'm so concerned with. Follow my stupid against the grain advice or stick within your limits wisely.

Both my Combats have brake power enough to stoppie, especially Ms Peel, which slowed/stopped better than any cycle I've tried or tested against. I even tried stoppie on steep down hill tarmac, gives me fear spikes in groin ok, but could not stay on bike braced like a maniac, always had to back off or be thrown over the bars. No way can other bikes stop that harsh, they stoppie or slide first so must back off the deceleration or crash. I really don't ever want to stoppie in real life as interferes with hi G pull downs, but it looks so cool I would like to get Peel to do it, maybe on pure race tire some day.

But no way can I get enough front traction on new 100 tire on un-tammed Trixie to do more than just slide front barely unloading rear enough its totally useless to help slow. I sometimes jab rear an instant ahead of front brake to squat bike first but thats more for the loose stuff than on pavement. I'm been too scared to slide Trixie's front for a few bike lengths slowing down like i did almost daily on Peel trying with all my might and 'skill' to get a real stoppie. I am only brave enough on Trixie to slide locked front while speeding up from walking speed with feet out - just in case THE Hinge onsets like a blow out front can do ya. I got too freaked out on down hill on Peel with my butt thrown up where head was and my head/trunk thrown over head light with rear tire lifted to what felt like a few inches and suddenly trying to pass the squalling front tire, but had no pilot control ability left as not really on bike to work controls like hold brake lever or bars. Only way I avoided crashes doing this is that Ms Peel is a one in a row tri-linked so will twist up chassis more than any other cycle yet not rebound but to Neutral instantly when loads suddenly cut. When I hopped on my SV with hotted up softened race tire I popped unintended stoppies on the first few pull downs I do going over all crests into unknown hazards I encounter so often. Then would pop un-intended wheelies to speed back up after cresting view ahead opens up. Ms Peel easy generated more control loads than race like bike *** just on her mere committing speeds to get to appointments, not even trying to kick up heels in a joy ride way.

On Trixie and SV I need brakes for the down hill sharp turn entries but not on Ms Peel so Peel is an abnormality, going too fast into turns for any brake slowing ability only can toss sideways to scrub speed off one direction to convert to energy in a new direction. On Peel at speed brakes can only be used to change direction or lean angle, either to slap down a low side or save a low side by the hi side. Had to do that a couple times on my SV 40 mph when traffic accident blocked my way on sand covered sharp blind 10 mph marked turn and stupidly fear reflex grabbed front brake while leaned and front washed right out into low side, stomped foot on rear, jerked bike back up, but then was aimed at tangent across oncoming lane right into the railing, with car approaching, but gritted teeth and got hard on front with bike totally inline upright till slowed enough front could be jerked to pull me back in my lane then hard on brake again to stop under a bike length from impact. I about pissed and shit and sweated and vomited all at once. Pure luck in panic state with nothing to lose saved me - not really my intended skill or practice level I could expect to repeat with Grace of God I no longer believe in.

montelatici · May 23, 2012

hobot said:
Dude I live in another orbit of Commando performance and that includes brake power on un-restricted Lockheed factory brake or Ms Peels re-sleeved 13 mm brake. Braking is the most important thing to me and force myself into working up panic attacks with locked front tire both on factory and up-graded brake power. I have full lock up on tap by either brake below 60 mph on 100 to 110 tires, brake power may limit everyone else but not me, I've no worries on power enough to lock up, its the dang surface and tire grip that I'm so concerned with. Follow my stupid against the grain advice or stick within your limits wisely.

Both my Combats have brake power enough to stoppie, especially Ms Peel, which slowed/stopped better than any cycle I've tried or tested against. I even tried stoppie on steep down hill tarmac, gives me fear spikes in groin ok, but could not stay on bike braced like a maniac, always had to back off or be thrown over the bars. No way can other bikes stop that harsh, they stoppie or slide first so must back off the deceleration or crash. I really don't ever want to stoppie in real life as interferes with hi G pull downs, but it looks so cool I would like to get Peel to do it, maybe on pure race tire some day.

But no way can I get enough front traction on new 100 tire on un-tammed Trixie to do more than just slide front barely unloading rear enough its totally useless to help slow. I sometimes jab rear an instant ahead of front brake to squat bike first but thats more for the loose stuff than on pavement. I'm been too scared to slide Trixie's front for a few bike lengths slowing down like i did almost daily on Peel trying with all my might and 'skill' to get a real stoppie. I am only brave enough on Trixie to slide locked front while speeding up from walking speed with feet out - just in case THE Hinge onsets like a blow out front can do ya. I got too freaked out on down hill on Peel with my butt thrown up where head was and my head/trunk thrown over head light with rear tire lifted to what felt like a few inches and suddenly trying to pass the squalling front tire, but had no pilot control ability left as not really on bike to work controls like hold brake lever or bars. Only way I avoided crashes doing this is that Ms Peel is a one in a row tri-linked so will twist up chassis more than any other cycle yet not rebound but to Neutral instantly when loads suddenly cut. When I hopped on my SV with hotted up softened race tire I popped unintended stoppies on the first few pull downs I do going over all crests into unknown hazards I encounter so often. Then would pop un-intended wheelies to speed back up after cresting view ahead opens up. Ms Peel easy generated more control loads than race like bike *** just on her mere committing speeds to get to appointments, not even trying to kick up heels in a joy ride way.

On Trixie and SV I need brakes for the down hill sharp turn entries but not on Ms Peel so Peel is an abnormality, going too fast into turns for any brake slowing ability only can toss sideways to scrub speed off one direction to convert to energy in a new direction. On Peel at speed brakes can only be used to change direction or lean angle, either to slap down a low side or save a low side by the hi side. Had to do that a couple times on my SV 40 mph when traffic accident blocked my way on sand covered sharp blind 10 mph marked turn and stupidly fear reflex grabbed front brake while leaned and front washed right out into low side, stomped foot on rear, jerked bike back up, but then was aimed at tangent across oncoming lane right into the railing, with car approaching, but gritted teeth and got hard on front with bike totally inline upright till slowed enough front could be jerked to pull me back in my lane then hard on brake again to stop under a bike length from impact. I about pissed and shit and sweated and vomited all at once. Pure luck in panic state with nothing to lose saved me - not really my intended skill or practice level I could expect to repeat with Grace of God I no longer believe in.

Well, exciting stuff. But, I ride very conservatively (read slow) on the street whether with the Guzzi or the Commando. I leave the exciting stuff to the little Yamaha TD-3 on the track.