BT-023 and tracking

DavidR8

Site Supporter
Joined
May 31, 2017
Messages
1,220
Location
Vancouver Island, British Columbia
Bike
2013 BMW R1200RT
STOC #
8968
I have BT-023's on our ST1300.
When I encounter a tar strip or pavement crack that's parallel to my direction, the tires 'grab' it and really throw the bike off course. Almost like the front goes down one side and the rear down the other.
The disruption is so dramatic that I actively avoid them when riding.
Pressure are according to tire spec and I believe suspension is setup correctly.
I've never ridden a bike that reacted so dramatically to a tar strip.

Has anyone else experienced this?
 

pumper316

SaTx Speed Demon!
Joined
Feb 22, 2017
Messages
121
Location
San Antonio, TX
Bike
'04 ST1300A
It's the tires! Another reason why I love the Michelin PR4's. Absolutely no tracking over tar snakes even at 70-80 mph.
 
OP
OP
DavidR8

DavidR8

Site Supporter
Joined
May 31, 2017
Messages
1,220
Location
Vancouver Island, British Columbia
Bike
2013 BMW R1200RT
STOC #
8968
Thanks all! I'm glad it's the tires and not the bike.
Based on the 2000 kms I've put on these since buying the bike in Sept I'm really sure I won't be putting Bridgestones on STella in the Spring.
Likely PR4GTs as I ride year round which means rain from Nov-Feb.
 

BakerBoy

It's all small stuff.
Joined
Jan 31, 2008
Messages
5,454
Location
Golden, Colorado
STOC #
1408
I'll offer a little different view: it's not a BT023 problem. All tires do it--unless there's an outright tire failure underway, the squirrely response is normal. I don't recall any tire brand or model that I've used over the last 30+ years that was stable on tar snakes. And I've run many brands and models over the years on many motorcycles, and I ride almost exclusively in the freeze-thaw damaged roads of high elevations where tar snakes are very common.

A bigger effect [than tire] I've noticed is width of the tar snake, orientation of the tar snake (in line with lane vs. perpendicular to lane), whether it is in a corner or on a straightaway, whether the tar snake spans over a slight elevation change (one lip of the gap higher than the other), and what type of tar was used. Some tars are very slick, and others are less slick (or have had grit pressed into their surface, such as I've seen in Montana). And given that the roadway has cracked, there are forces leading to the surface cracking, and often the pavement is no longer flat across the gap--even if there was no tar over the gap, the slight elevation change makes the crack feel like it has slick tar on it.

I do expect there's some change of the squirrely feeling that can come in as the tire ages (how the tire has worn and/or carcass has reshaped), current pressure, road surface temperature, bike's rake, and other factors. But I think that is secondary to basic physics of a motorcycle tire.

With motorcycles, the outermost portion of the contact patch slides slightly all the time (as that outer portion is at a different wheel diameter than the center of the contact patch)--this happens even when going straight or when riding through a turn on a smooth (non-tar-snaked) road, but in that case the slippage/flexing is continuous, doesn't disrupt the bike's line, and just isn't noticed.

All tires will shift a bit when transitioning from pavement to tar and back (each surface having different grip and as the contact patch moves over the tar, the tire flexes and pulls in response to the transitions).
 
OP
OP
DavidR8

DavidR8

Site Supporter
Joined
May 31, 2017
Messages
1,220
Location
Vancouver Island, British Columbia
Bike
2013 BMW R1200RT
STOC #
8968
With motorcycles, the outermost portion of the contact patch slides slightly all the time (as that outer portion is at a different wheel diameter than the center of the contact patch)--this happens even when going straight or when riding through a turn on a smooth (non-tar-snaked) road, but in that case the slippage/flexing is continuous, doesn't disrupt the bike's line, and just isn't noticed.

All tires will shift a bit when transitioning from pavement to tar and back (each surface having different grip and as the contact patch moves over the tar, the tire flexes and pulls in response to the transitions).
Thanks, All I can say is that the difference between the ST and my Tiger 955 on Anakee 2's is really dramatic.
The first time it happened I darn near came off because it felt like the beginning of a tank slapper. Since then I've avoided riding over them. Yesterday in the rain, due to traffic conditions I had no choice but to hit a crack about 8 ft long and maybe 2 inches wide. Scared the living cr@p out of me.
 

jfheath

John Heath
Site Supporter
Joined
Mar 18, 2006
Messages
2,786
Age
69
Location
Ilkley, W Yorkshire, UK
Bike
2013 ST1300 A9
2024 Miles
000679
STOC #
2570
Agree with everything said so far, but I have to say that my experience with the 023 was not good. First of all, they need to be the GT version for the ST1300, and they may not be.
Second, the BT023GT wore down quite rapidly on the sides, and they started wallowing about half way through their life - which for me was about 2000 miles. Plenty of tread in the centre, but anything off centre was badly worn - I'll come back with a pic that I posted here at the time.

Undoubtedly, white lines and tar strips will affect the bike, but the tyres can make this better or worse. The BT020 F rated and the T30 GT rated are both pretty good in comparison.

Don't go away - I'll find this picture.

Here you are - See my pics in post #1 and replies from others.
 
Last edited:
OP
OP
DavidR8

DavidR8

Site Supporter
Joined
May 31, 2017
Messages
1,220
Location
Vancouver Island, British Columbia
Bike
2013 BMW R1200RT
STOC #
8968
Thanks John,
That's some really nasty wear.
I don't know how many miles are on my BT-023's but they are not worn out. I will ride through to spring on them and then swap them out.
Perhaps the prices on the PR4's will come down now that the 5's are out.
 

jfheath

John Heath
Site Supporter
Joined
Mar 18, 2006
Messages
2,786
Age
69
Location
Ilkley, W Yorkshire, UK
Bike
2013 ST1300 A9
2024 Miles
000679
STOC #
2570
I don't know how many miles are on my BT-023's but they are not worn out.
Sorry - i wasn't suggesting that yours were worn out - i am sure you would have considered that - i was commenting that on my one and only pair, the rear started to behave very differently on the sides after just 2000 miles. And i am no peg-scraper.
 
Joined
Feb 25, 2016
Messages
4,759
Location
Northumberland UK
Bike
VStrom 650
Agree with what's been said and +1 baker boy, all tyres do it and wear will make it worse. On my 11 the 023's and T30's were better than Avon's. I found that if you don't fight the bitumen strip the bike will just correct itself, don't grip the bars too tight.
As an aside my car on wide run flats is far worse than the bike and can often veer a foot either way because of road defects, again just let it correct itself.
Upt'North.
 
OP
OP
DavidR8

DavidR8

Site Supporter
Joined
May 31, 2017
Messages
1,220
Location
Vancouver Island, British Columbia
Bike
2013 BMW R1200RT
STOC #
8968
Sorry - i wasn't suggesting that yours were worn out - i am sure you would have considered that - i was commenting that on my one and only pair, the rear started to behave very differently on the sides after just 2000 miles. And i am no peg-scraper.
No worries, I didn't think you suggested that. I was more musing that mine won't be replaced with another set of Bridgestones when they are worn out.

I ride a lot in the rain and want better security on wet roads. It think the PR4GTs will be my next set.


Sent from my iPhone using Tapatalk
 
Top Bottom