Darksiders beware...

Gaoler said:
I recently watched a video that touched on the DS and it's potential for maybe not being such a good idea...
'Granted the guy doing the talking is a representative of a motorcycle tire manufacturer so he has a vested interest in people buying motorcycle tires over car tires, but... What he revealed made a lot of sense.
Cross sectioning and comparing a bike tire's construction to a passenger vehicle tire and explaining the differences between them as well as the reasons for the differences leads me to conclude... apples and oranges.
In my mind they're different enough to just leave well enough alone.

Oh, and he didn't like balance beads either 😁
Click to expand...
Fair enough. I would love to see two roughly equivalent bikes and riders on a track with one on normal motorcycle tires and one with a normal car tire. That should be a reasonable wort-case scenario. If the car tire has similar pace and survives, that seems good enough. Added longevity is a win for the car tire.
 
GreyGhost said:
Fair enough. I would love to see two roughly equivalent bikes and riders on a track with one on normal motorcycle tires and one with a normal car tire. That should be a reasonable wort-case scenario. If the car tire has similar pace and survives, that seems good enough. Added longevity is a win for the car tire.
Click to expand...

On the track, when cornering at the limits of traction, the moment the bike tips in, it's gonna be low-side city.

So yes, the tire may fare better at the end of the lap, but the rest of the bike...?

Based on their V-shaped profile, motorcycle tires are designed to increase contact patch at initial tip-in for more grip. That car tire has a 90-degree edge for a contact patch.
 
Lightcycle said:
On the track, when cornering at the limits of traction, the moment the bike tips in, it's gonna be low-side city.

So yes, the tire may fare better at the end of the lap, but the rest of the bike...?

Based on their V-shaped profile, motorcycle tires are designed to increase contact patch at initial tip-in for more grip. That car tire has a 90-degree edge for a contact patch.
Click to expand...
Maybe. It might not be as bad as you expect though. That's why the test would be interesting. Car tire is miles below it's max load so there is a chance the profile is more curved than we expect. I suspect that out at the limit, the car tire will have substantially less grip than a bike tire but I don't know for sure. If you compared race tires to car tires, I expect a big gap but not many people are running race tires on the street (and if they are, they don't have enough heat in them and they are probably the slipperiest and shortest life option).
 
Lightcycle said:
. It would have happened much earlier and worse on a car tire.
Click to expand...
Why a definitive statement without experience to back it up? You expect the harder compound is a guaranteed issue? You think the transition from vertical to leaned over is too harsh and that will upset the bike? I think you're probably correct but given the anecdotal experience of darkside riders, I'm willing to maintain an open mind until I have actual data. It would be interesting to have a camera set to watch the shape of the car tire as you lean over. I won't be surprised if the tread remains mostly in contact with the road until you get close to the lean limit (especially on a cruiser where they are typically fitted).
 
GreyGhost said:
Why a definitive statement without experience to back it up? You expect the harder compound is a guaranteed issue? You think the transition from vertical to leaned over is too harsh and that will upset the bike? I think you're probably correct but given the anecdotal experience of darkside riders, I'm willing to maintain an open mind until I have actual data. It would be interesting to have a camera set to watch the shape of the car tire as you lean over. I won't be surprised if the tread remains mostly in contact with the road until you get close to the lean limit (especially on a cruiser where they are typically fitted).
Click to expand...

If car tires were equal to motorcycle tires in cornering grip *and* superior in longevity, why aren't professional racers using square tires? Tire life is a major issue during the course of a full-length race and if going DS solves that, then surely square tires would be the obvious choice at all levels of motorcycle racing.
 
Lightcycle said:
If car tires were equal to motorcycle tires in cornering grip *and* superior in longevity, why aren't professional racers using square tires? Tire life is a major issue during the course of a full-length race and if going DS solves that, then surely square tires would be the obvious choice at all levels of motorcycle racing.
Click to expand...
We're not talking about racing. We're talking about safe tires on the street (and most likely on a cruiser) and how to quantify that. As I said before, a motorcycle race tire will win in ultimate grip on the track.
 
GreyGhost said:
We're not talking about racing. We're talking about safe tires on the street (and most likely on a cruiser) and how to quantify that. As I said before, a motorcycle race tire will win in ultimate grip on the track.
Click to expand...

Actually, you were first to bring up the track:

GreyGhost said:
I would love to see two roughly equivalent bikes and riders on a track with one on normal motorcycle tires and one with a normal car tire.
Click to expand...

To me, the track means cornering at the limits. Can a sportbike fitted with square tires even provide any grip at 55-60 degrees of lean angle while while throttling out of the corner, much less do it safely?
 
Lightcycle said:
Actually, you were first to bring up the track:



To me, the track means cornering at the limits. Can a sportbike fitted with square tires even provide any grip at 55-60 degrees of lean angle while while throttling out of the corner, much less do it safely?
Click to expand...
I was using the track as a controlled environment to both see the performance vs typical street tires and to stress the ds tires to the max. If the bead stays seated when hot on the track, it should be fine on the street. In no world was I ever suggesting that ds is the best option for a track bike.

Have you ever seen a darkside sport bike? They are almost exclusively cruisers.

Darkside riders say cornering performance is solid. Going head to head would move that from anecdotal (and potentially biased) to real numbers.
 
Lightcycle said:
RyanF9 to the rescue:


Actual video starts at 2:30
Click to expand...
He made no comment about grip in a corner for the rear. He didn't like the self-righting nature and he rightly pointed out that you waste some front traction fighting the darkside when leaned over. A front washout really sucks. Playing with tire pressures can drastically change shape and handling characteristics. He made no comment on that. Manufacturers recommended pressure applies to the recommended size so I have no idea what he picked.
 
GreyGhost said:
He made no comment about grip in a corner for the rear. He didn't like the self-righting nature and he rightly pointed out that you waste some front traction fighting the darkside when leaned over. A front washout really sucks. Playing with tire pressures can drastically change shape and handling characteristics. He made no comment on that. Manufacturers recommended pressure applies to the recommended size so I have no idea what he picked.
Click to expand...

It's not just about static grip given a level of lean, it's the about the transition from straight-up to tip-in.

A motorcycle tire has a smooth, rounded profile that doesn't upset the chassis at tip-in, thus preserving contact with the ground.

Even if there is a bit of flex on the DS tire to maintain grip, there is always going to be a more noticeable transition going from straight-up to tip-in on a square tire vs a rounded one. I've read many darksider accounts that confirm this - most common DS response is "you expect it, so you just adjust your riding for it". Fine if just piddling around at slower speeds on long sweepers, but when wicking it up on tight twisties, that transitional bump may be enough to upset the chassis and interrupt contact with the ground.

GreyGhost said:
Have you ever seen a darkside sport bike? They are almost exclusively cruisers.
Click to expand...

It's not a meaningful discussion if you're going to put parameters on what a darkside tire is good or not good for. As WB pointed out, you may not intend to ride above the limit of your tires, but extenuating circumstances forcing you to perform evasive maneuvers might require additional grip at transitions that you may not have planned for. Is saving that extra $ worth losing that safety margin?
 
Lightcycle said:
It's not a meaningful discussion if you're going to put parameters on what a darkside tire is good or not good for. As WB pointed out, you may not intend to ride above the limit of your tires, but extenuating circumstances forcing you to perform evasive maneuvers might require additional grip at transitions that you may not have planned for. Is saving that extra $ worth losing that safety margin?
Click to expand...
You brought up 55+ degrees of lean angle. A cruiser hits hard parts long before that. The extension of your argument is everyone should ride sport bikes as cruisers are heavy and have severely restricted lean angle so they are dangerous in emergencies. Like everything, it is all matters of degree. I suspect the difference in handling from a sport bike to a cruiser exceeds the change in handling for a cruiser going darkside.
 
GreyGhost said:
The extension of your argument is everyone should ride sport bikes as cruisers are heavy and have severely restricted lean angle so they are dangerous in emergencies.
Click to expand...

You could look at it that way.

If you choose to ride a cruiser, you know you won't be able to perform evasive maneuvers as well as other bikes do.

However, why would you handicap yourself twice by choosing to put a lesser-capable tire on a lesser-capable motorcycle?

I know of no dark-sider that will claim a square tire will handle better than a round one. It's purely a $$$ savings measure.
 
You must log in or register to reply here.
Back
Top Bottom