Author Topic: S6 tyre pressures  (Read 4530 times)

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Offline Michael Scott

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S6 tyre pressures
« on: 07 Sep 2009 at 14:49 »
I now have a few miles under my belt and making progress with clutch slip
The next problem to be chased is tyre pressures. Although I have reached 42psi for the front tyre I still ground the rim on even quite small pot holes. This explains the "dings" on the rims as received!
I have not done the calculations but it does not take much guessing to arrive at the conclusion that the weight of the bike exceeds the capacity of the tyre to resist the forces.
Any solutions, bright ideas?
Driving slower comes in around plan Z!
Michael

Offline Chris

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Re: S6 tyre pressures
« Reply #1 on: 07 Sep 2009 at 15:33 »
Hi Michael
     Are you sure that your pressure gauge is working correctly and indicating the correct pressure? I do not possess an S6 but I have never ever "dinged" a rim even with much lower pressures than 42psi on any of my machines with either beaded edge or wired edge tyres. In severe pot holes I have bottomed the fork suspension without the rim coming into contact with the road. I have never had this problem reported to me before by friends owning an S6. Has any other S6 rider suffered the same problem? Chris.

Offline eddie

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Re: S6 tyre pressures
« Reply #2 on: 07 Sep 2009 at 18:48 »
Hi Michael,
                 I am in agreement with Chris - there must be a problem with your tyre gauge - or you have an old type connector that doesn't lift the Schrader valve, thus giving the pressure needed to lift the valve rather than the pressure in the tube. Assuming you have a 3.25 x 19 front tyre, I would expect 24-26lbs to be plenty. Any more will make the steering very light, and also increase the chance of the front breaking away. I am also puzzled by the fact that you report that the rim is 'dinged' by grounding on potholes, but you don't mention any punctures. I would have expected the tube to get cut before the rim suffered any damage (unless, of course, the rims are old and rusted from the inside, and therefore, close to collapse anyway).
         Just for reference, I run my F31 based sprinter with tyre pressures 22 in the front(3.00 x 21 tyre) and 16 -18 in the back (3.50 x 18 tyre) without any problems.
                                Regards,
                                            Eddie.

Offline Ian

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Re: S6 tyre pressures
« Reply #3 on: 07 Sep 2009 at 22:18 »
Just to clarify - is the S6 beaded edge or well wheels ? My OC is beaded edge 26x3 and I run about 35PSI - no problems at all. For well wheels (19") we run about 20-25 PSI on the bikes I have with them including some very sporty late 20s and 30s machines with never a problem.

Offline graeme

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Re: S6 tyre pressures
« Reply #4 on: 08 Sep 2009 at 00:01 »
The S6 should have well base wheels - ie, wired edge tyres fitted. On my S6 I run 20psi in the front and 22 in the back - any more and you get an increasingly uncomfortable ride. When I used to race a vintage Rudge I had 18psi in both tyres, so the rubber got sticky. 42 psi is clearly wrong - you would surely end up on your ear quick with that sort of pressure.

Offline Michael Scott

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Re: S6 tyre pressures
« Reply #5 on: 14 Sep 2009 at 08:07 »
I have at last found time and nice weather to really concentrate on my problem.
Not sure what a"well rim" is but my my tyres and rim are perfectly conventional beaded edge and sound after following grit blasting and powder coating. But with pre-existing little dings!

Careful inspection of the tyre shows no witness marks/damage to the walls. So the above and wise heads in the local VMCC confirm that what it feels like to me as I am riding cannot be the source of the "crash"  Incidentally I am now back to 32 psi

Careful inspection of the forks shows no witness marks to show what is hitting what.  The only possibility is the "damper" in the centre of the spring and that needs to be dismantled to check.  Heading that way because the forks will come to pieces to be painted in the next few weeks.

It is hard to see what is happening when you are riding because things happen so quickly.  Normal riding is nice and comfortable with the suspension seeming to work quite normally.  Sleeping policemen, potholes, drain covers and slightly raised kerbs across entrances need to be approached very slowly.

I will concentrate on this over the next few weeks and post a note when I think that I have solved the problem.

Thanks
Michael

Offline Ian

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Re: S6 tyre pressures
« Reply #6 on: 14 Sep 2009 at 22:02 »
Well rims are what most people would consider "normal" for bikes from mid-late 20s onwards. Beaded edge the rim has a hooked edge that mates up with a corresponding flange on the tyre to hold it in place. Most veterans and early-mid vintage had those.

 

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