Michelin Road 5 GT odd wear?

[pmatulew]

At almost 4,000 miles. What have I done to this Road 5 GT rear tire? The front looks normal and is actually wearing quite well. 42/42 Mixed riding mostly two-up.

 

[OkieRider]

That's called cupping and it's normally the result of under inflation. It comes from the tire squirming under acceleration or deceleration loads. It can also be caused by poor suspension condition or improper settings. If the tire is bouncing up and down off the road surface, it won't wear properly. My first guess is your rear suspension is not set up properly for 2-up riding.

 

[Igofar]

Yup, you need probably need to service your pre-load adjuster, correct your preload and damping settings, and get a better tire pressure gauge.

 

[CYYJ]

Yup, you need probably need to service your pre-load adjuster, correct your preload and damping settings, and get a better tire pressure gauge.

Here are links to posts in our forum that explain how to do the above:

Pre-Load Fluid replenishment

Adjusting Rear Shock Rebound

Both are fairly easy tasks, although the preload fluid replenishment will take you a few hours of work if you have not done it before. Best to do that job inside a heated, well-lit garage where you can leave the bike overnight if the job is only half-finished and you want to finish it the next day.

Do the rebound adjustment AFTER you have replenished the preload fluid.

Michael

 

[SMSW]

How many miles on your shock? A number of guys have said rear shocks last around 50,000 miles - some last longer, some less.

 

[SMSW]

Both are fairly easy tasks, although the preload fluid replenishment will take you a few hours of work if you have not done it before. Best to do that job inside a heated, well-lit garage where you can leave the bike overnight if the job is only half-finished and you want to finish it the next day.

IIRC, the first time I did the preload refill it took a couple of hours. Get your mineral oil and hypodermic fork oil filler ready, and go ahead with this service. When you pull the knob off the preload adjuster be careful not to loose the little ball bearing and spring that give you the detents. I spread an old sheet on the floor around the bike to grab that steel ball when I drop it.

I cannot tell from your pics if you have tread left over the wear bars. If you do, consider putting this service off for another month until your winter layup (you don't ride over the winter in PA, do you?). Then you will have plenty of time to change the tires, check sag front and rear, refill the preload adjuster, etc.

 

[Al Gully]

I've never tried Michelins on my ST, and never seen that type of wear on any Bridgestone's rears.
I normally wear the rear out till it's bald and change it out.

Also, never touched the Preload or rebound adjuster since I bought it in 2009.
Maybe I should start monkeying around with them. Lol.

I've tried all the Brigestones and find the "GT's" prefix are best for these heavy bikes.
BT 023 GT's, T30 GT's T31 GT's and now the T32 GT's

 

[dduelin]

The ST1300 with OEM suspension is undersprung for most American riders and all two up couples. The 900 lb spring simply cannot cope. The best we can do with 300+ lbs in the saddle and stock suspension is set lots of preload and set perhaps 1.5 to 2 turns in from full soft on the rebound screw. 42 psi in the tires.

 

[OkieRider]

I've never tried Michelins on my ST, and never seen that type of wear on any Bridgestone's rears.
I normally wear the rear out till it's bald and change it out.

Also, never touched the Preload or rebound adjuster since I bought it in 2009.

Much 2-up?

 

[Al Gully]

Much 2-up?

All 2 up and also with a uni-go trailer for a few years.
The T31 GT now is single rider as the wife has her own ride.
She keeps bugging me now to go riding, that's sure a change from years gone by

 

[OkieRider]

I'm on T31 GTs. I like Bridgestone tires, generally. What pressure do you run?

 

[ColinW1981]

and get a better tire pressure gauge.

As you've brought it up, inquiring minds would like to know what the ST Whisperer recommends for a tire pressure gauge?

 

[Al Gully]

I'm on T31 GTs. I like Bridgestone tires, generally. What pressure do you run?

I always run my Bridgestones spot on 42 psi. Seen them rise as high as 52 psi when it was 103 F out doing 85 MPH
I used to have continuous pressure and temperature readings on my TPMS.

 

[Igofar]

As you've brought it up, inquiring minds would like to know what the ST Whisperer recommends for a tire pressure gauge?

Intercomp 360067 $50
Longacre 53036 $45
Motion Pro Digital Tire Pressure Gauge 0-60 $88

 

[ColinW1981]

Intercomp 360067 $50
Longacre 53036 $45
Motion Pro Digital Tire Pressure Gauge 0-60 $88

Thank you kind Sir!

 

[Willsmotorcycle]

 

[pmatulew]

Did the preload adjuster at the beginning of the season. Have actually been running this year with more preload than I have in the past. Taller for my short legs to manuever but it seems to handle better. How much sag are we supposed to have? Haven't done anything with the rebound damper. Suppose I need to have a look at that.

 

[dduelin]

Did the preload adjuster at the beginning of the season. Have actually been running this year with more preload than I have in the past. Taller for my short legs to manuever but it seems to handle better. How much sag are we supposed to have? Haven't done anything with the rebound damper. Suppose I need to have a look at that.

Most tuners would have about 35 to 40 mm sag with the bike loaded with rider(s) and normal stuff carried in the bags. If the preload adjuster is in good shape it isn't difficult to get sag in this range by cranking in a lot of preload but when sag is measured with rider(s) off the bike, static sag, will be close to zero. This indicates the spring is much too soft. The result is the bike will be hitting the shock's bump stop often when loaded to normal riding weight and going down the road. Of course the bike can be ridden like this and we get used to the way it is. Every time I've done a suspension upgrade I'm reminded that until I get better suspension the suspension I had was good enough. We also have to remember that because both front and rear is undersprung, upgrading just one end or the other can make handling worse by raising the ride height and changing the steering geometry. With stock suspension the ST1300 does respond well to lots of shock preload with improvements to ride and to handling.

 

[OkieRider]

Doing one end of the other should be ok unless one end is much softer than the other.

 

[dduelin]

Doing one end of the other should be ok unless one end is much softer than the other.

That's the thing. Both ends are really soft. Under my geared up wt. of 165 lbs the forks had 47 mm of rider sag (44% of travel). I added fork preload to a target sag of 36 mm (33%) which slowed the steering geometry quite a bit. If I left the shock at the recommended 7 clicks the sag and resultant steering geometry was much slower than designed and I liked because the rear end was sagging so low. The bike ran wide in corner exits so I raised the fork tubes in the triple clamp as much as I could and ran about 30 mm of rear sag (24 %, or less than optimal) to sharpen the steering.

To the original complaint, previous Michelin Pilot Road generations did have a reputation for this lumpy wear pattern and I moved away from the brand but with the introduction of the Road 5s I came back to the brand and this type of lumpy wear I believed to be a thing of the past. Many believe, myself included, that low tire pressures contribute to the scalloping. I'm on a third set of Road 5s on my RT and I love them but the RT is much lighter. I'm not sure it's fair comparision to a two up ST1300.