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DannoXYZ · September 5th, 2018, 04:42 AM

So I towed exact same bike on exact same trailer with two different cars.

RWD

FWD

Now, guess what happened to my braking distances using normal pedal-pressure? It INCREASED!!! For BOTH cars!!!
Guess what happened to my braking distances under maximum braking? It INCREASED!!! For BOTH cars!!!

Don't wait until an emergency situation under maximum braking to discover that you can't slow down as quickly. It's simple physics, F=ma. With same braking force F, acting on higher mass m, gives you slower deceleration -a. Trying to lift 200-lbs over your head is gonna be harder than 120-lbs for same strength. So practice maximum-braking by starting with normal pedal-pressure braking, then increase it each time to get used to different feel. In fact, my Porsche had worse, more increased distance, than Wagon because it's lighter. So same weight of bike+trailer shoved lighter Porsche larger increase in braking distance than their unladen distances.

The dynamic nature of braking causes weight-shift to front wheels. Harder you brake, larger the force pushing backwards, and more weight shifts to front wheels.

You can see that tyres that are gonna be overloaded under braking is gonna be front ones. As can also be evidenced by differently sized brakes in front vs. rear. Same with autos, just not as extreme as with bikes due to lower C.O.G. and longer wheelbase. An FWD auto with 60/40 f/r weight distribution may reach 70/30% with the front tyres facing twice as much load as rear, completely overwhelming front ones.

That's why cars with rearward weight bias such as Porsche 911 with 37/63% f/r distribution have shorter braking distances than just about anything else. Because under braking, forward weight shift gives it perfect 50/50 f/r rear loading for maximum traction without overloading front tyres. Heck, even a Toyota MR2 with 43/57% distribution can almost rival 911's braking due to its rearward weight bias.

That's why racers of FWD cars do everything possible to lighten up front-end and move weight to back to improve braking performance. Most common is relocating battery to boot, some even put radiator back there.

So.... Practice your braking beforehand. Don't wait until panic situation and find out you can't stop as well. That will ALWAYS be the case, simple physics, and overloading front tyres will just make it worse. I get 15-18ft shorter stopping distances from 70mph by piling as much stuff in boot of Wagon as possible, compared to having it up front.

September 5th, 2018, 04:42 AM	#13
DannoXYZ ninjette.org certified postwhore Name: AKA JacRyann Location: Mesa, AZ Join Date: Dec 2011 Motorcycle(s): CB125T CBR250R-MC19 CBR250RR-MC22 NSR350R-MC21 VF500F CBR600RR SFV650 VFR750F R1M ST1300PA Valkyrie-F6C Posts: A lot. MOTY - 2018, MOTM - Nov '17	So I towed exact same bike on exact same trailer with two different cars. RWD FWD Now, guess what happened to my braking distances using normal pedal-pressure? It INCREASED!!! For BOTH cars!!! Guess what happened to my braking distances under maximum braking? It INCREASED!!! For BOTH cars!!! Don't wait until an emergency situation under maximum braking to discover that you can't slow down as quickly. It's simple physics, F=ma. With same braking force F, acting on higher mass m, gives you slower deceleration -a. Trying to lift 200-lbs over your head is gonna be harder than 120-lbs for same strength. So practice maximum-braking by starting with normal pedal-pressure braking, then increase it each time to get used to different feel. In fact, my Porsche had worse, more increased distance, than Wagon because it's lighter. So same weight of bike+trailer shoved lighter Porsche larger increase in braking distance than their unladen distances. The dynamic nature of braking causes weight-shift to front wheels. Harder you brake, larger the force pushing backwards, and more weight shifts to front wheels. You can see that tyres that are gonna be overloaded under braking is gonna be front ones. As can also be evidenced by differently sized brakes in front vs. rear. Same with autos, just not as extreme as with bikes due to lower C.O.G. and longer wheelbase. An FWD auto with 60/40 f/r weight distribution may reach 70/30% with the front tyres facing twice as much load as rear, completely overwhelming front ones. That's why cars with rearward weight bias such as Porsche 911 with 37/63% f/r distribution have shorter braking distances than just about anything else. Because under braking, forward weight shift gives it perfect 50/50 f/r rear loading for maximum traction without overloading front tyres. Heck, even a Toyota MR2 with 43/57% distribution can almost rival 911's braking due to its rearward weight bias. That's why racers of FWD cars do everything possible to lighten up front-end and move weight to back to improve braking performance. Most common is relocating battery to boot, some even put radiator back there. So.... Practice your braking beforehand. Don't wait until panic situation and find out you can't stop as well. That will ALWAYS be the case, simple physics, and overloading front tyres will just make it worse. I get 15-18ft shorter stopping distances from 70mph by piling as much stuff in boot of Wagon as possible, compared to having it up front.