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Having difficulty figuring this one out; riding home a few miles last night and throttled up to catch a mate when the front went to jelly - just like a front puncture!

Managed to keep her under control and limped home very carefully the last few miles with every corner feeling like I'm on ice.

So I jacked up the rear today and checked for swinging arm/wheel bearing movement and tyre pressure/nails etc., everything was solid and free of foreign objects.

Jacked up the front and checked head & wheel bearings for movement; all solid.
Checked front tyre similar to rear and all looks good although the front tyre [Cobra AV71 @ 50psi] does look a bit flat.

So I now wonder what the hell was going on there...?

You say 50 pounds of air pressure in the front tire.
Is this when it looked "a bit flat"???

Paul H

Yep, 50 in the front and 45 rear, as mentioned in The Book.

Tread is also good on both tyres but that front has a broad contact patch with the ground of about 6" looking at it from side on.

Damn weird!

Maybe belt separation causing it to spread? I would call Avon to see what they say.

I've had that on a front tyre before and you're probably right Bill.
I'm unsure of the manufacture date and history so I've bitten the bullet and ordered a new Cobra today.
I do know Tom at MBH did fit a new rear before sending the bike.
Hopefully that'll fix it

RocketSteve wrote:...when the front went to jelly...

You weren't riding during the solar eclipse, were you?

Funny you should say that, there was an Alien element to it all

Have you checked your tire pressure with more than one tester. If you say it's got b50psi and looks flat maybe your tester is not accurate? Just a thought?

misfit wrote:Have you checked your tire pressure with more than one tester. If you say it's got b50psi and looks flat maybe your tester is not accurate? Just a thought?

My thoughts too so I ran a 2nd test with a more expensive pump, 50 psi result was the same.
It's like the middle part of the rubber tread has gone very soft.
Pick up my new tyre tomorrow so we'll see what it's like inside...

Hi Steve,

I checked my front = 6" contact patch from the side is good - Michelin Commander @ 48psi. But the tread is definitely not 'soft' on any part of the tyre. It feels very firm, even rock-hard I'd say. Any softness would be a handling disaster as you described and indicate delamination.

Sounds defo like a case of belt separation - notably the main causes are bad pothole hits (had a good few of those on our roads) especially to high pressured tyres (ours are higher than on most, if not all, other bikes). Another possibility is chemical issue on manufacture but it does sound like the hard tyre/pothole hit scenario.

Glad it wasn't at higher speeds - thinking I was out a lot this weekend regulalrly hitting 80-100 - a delamination then would be major diaper-time! I'll be getting a new tyre on in the next 2 months.

Hi Gordon,
I'm off to Vancouver via Calgary in a week or so and will need to chat before I fly - call you tomorrow night maybe?

check your frame behind the rad. Aldo's bike was acting weird a few years ago and the front frame, we took off in three pieces. check the upper motor mounts also.
Drink less beer!!!!

Checked as suggested V8Norm and found a few lines on the front mounts, unsure if these are cracks or standard as they're the same on both sides.

Took a few photos of the top front right side.

Just my 2 cents worth. Frame cracks/splits don't usually happen in a perfectly straight line like the photos you are showing us. Good luck in your troubleshooting!

If these lines don't appear on other Hosses then I think these are very likely to be cracks, do any others in the Forum have these lines?

If they need welding it looks like it can be done with just taking off the radiator and tank...

I would thoroughly clean the areas of the suspected cracks and do a dye penetrant test to verify whether or not you have cracks.

I second Marks suggestion. Also, you could put it in gear, give a little throttle and have the motor torque over and see if the crack increases.

Hi Steve,

Looks like possible paint cracks, I have a few areas where the paint has cracked and lifted off the frame metal and no crack underneath. I would expect that any cracks that lead to riding instability would be big noticable ones, with clear movement of linked cycle parts when jacked up.

I'd strip the paint and test the base metal on the upper mounts, then fingers crossed it's just some repainting needed. The headstock is unlikely to be fractured to that extent of instability without being more obvious.

I'm in tonight (Thurs) or on the mobile tomorrow.

Thanks for the heads up guys, I'm now fearing the worst and will be following your guidance on checking it out...

Gordon, got back late yesterday from Marks funeral in Coventry so haven't had a chance to ring you, will try during the week ahead.

Took the Radiator off this morning and my Welder assessed the whole steering head - he concluded it was free of cracks, the lines I found appear to be either fabrication or casting lines.

The black frame paint is so hard that if anything untoward took place underneath, it would also crack the paint and show up on the surface.

Better photos taken with the Rad removed; see what you think guy's...

Getting the front tyre changed this afternoon so we'll see if that was the original problem.

Just as I suspected, no cracks. The frame paint is powder coating, that is why it's so hard. Is your BH a bike or trike? If it's a trike I highly recommend mounting a new Avon "TRIKE" front tire on it. I really like mine. Again, Rocket Steve, good luck.

It's a bike Ron, fitted a new Avon Cobra MT90 B16 earlier today and (with a magnifying glass) I noticed it says 40 psi max on the side wall.

The Book says 50 psi so I'm going to playing safe with 40.
Hope to finish getting all the bits bolted back on tomorrow then take her for a careful test...

RocketSteve wrote:It's a bike Ron, fitted a new Avon Cobra MT90 B16 earlier today and (with a magnifying glass) I noticed it says 40 psi max on the side wall.

The Book says 50 psi so I'm going to playing safe with 40.
Hope to finish getting all the bits bolted back on tomorrow then take her for a careful test...

Personally I would not run below 45 lbs on a smallblock

My Michelin commander says 42psi cold (for normal bikes) my manual 49psi, but I run 46 as that's only 9% over tyre max and 9% under recommended and haven't had any cupping or stability issues.

The higher pressure is based on the higher weight we carry and the importance of tyre rigidity on stability. More pressure = smaller contact patch (+hotter tyre).

I rode through 6 hrs of torrential rain in Belgium last year returning from Pullman City - through standing water with no grip issues.

I'd be interested to hear of others' views...

My uneducated view - never exceed the tire manufacturer's recommendation. The MAX PSI on the tire is the pressure the tire needs to hold the maximum weight on the tire.

If BH is telling you to run more pressure, I would question that their recommendation is for your specific tire, or whatever tire the factory was running at that time.

A few lbs in either direction wouldn't necessarily hurt anything, but if you fill the tire to max cold - it will be more when the tire gets hot, the mfr takes that into account.