Author Topic: Fitting M+ onto Mavic disc rim  (Read 483 times)

velosam

  • '.....you used to be an apple on a stick.'
Fitting M+ onto Mavic disc rim
« on: December 15, 2018, 02:44:41 pm »
I have been struggling for about 3 hours to get a m+ tire onto a mavic disc rim.

I have finally got the tire on, with a judicious amount of packing tape,as I have no cable ties etc handy.

However, the tire will not seat onto the rim.  It simply keeps popping out - could the tire be too big for the rim or would it be something else?

I have inflated and deflated the tire several times and am now at my wits end!

vorsprung

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Re: Fitting M+ onto Mavic disc rim
« Reply #1 on: December 15, 2018, 03:28:06 pm »
On the one hand you seem to be saying that the tire is too small as you had trouble fitting it

On the other hand it's too big as it keeps "popping off".   Which is it?

Photos of the labels on the tire and tech details of the wheel/rim please
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velosam

  • '.....you used to be an apple on a stick.'
Re: Fitting M+ onto Mavic disc rim
« Reply #2 on: December 15, 2018, 03:40:36 pm »
the tire is a marathon plus 700 x 38c.

I don't know the rim as its what came with the bike.

I suspect its a mavic disc rim as I am pretty sure the vendor stated it had been and I know it had 28c tires on when I bought it. I have run M+32c on it with no issues.

If I had to guess I would state its the disc equivalent rim of the a719 as it looks similar.


Re: Fitting M+ onto Mavic disc rim
« Reply #3 on: December 15, 2018, 04:05:51 pm »
I had a similar thing recently with a 28mm tyre. There are 3 sizes of 28mm tube. 19-28, 25-32 and 28-47. I was trying to fit a 28-47 tube which was too big. Switched to a 19-28 and tyre fitted fine.

Re: Fitting M+ onto Mavic disc rim
« Reply #4 on: December 15, 2018, 06:55:12 pm »
I have seen something similar (M+ tyre and DT swiss tubeless rim).  The cure; new rim.

  I think that some tyres need a pronounced hook bead to seat correctly and some tubeless rims don't have one that is suitable.

You may get away with a narrower version of that tyre but then again if really want to use the wider one then a different rim may be necessary.

cheers

velosam

  • '.....you used to be an apple on a stick.'
Re: Fitting M+ onto Mavic disc rim
« Reply #5 on: December 15, 2018, 07:20:58 pm »
Now sorted, thanks all.  Turns out the tire is so out of size that you can safely fit a hand between the tire and the rim!!

New tire I think.

Re: Fitting M+ onto Mavic disc rim
« Reply #6 on: December 15, 2018, 11:33:06 pm »
apologies if this is obvious but if the tyre blows off the rim (for any reason) the forces are immense, and after a few times this can turn a tyre that was about the correct size when you started to one that is a really baggy fit on the rim.

 If/how quickly this happens depends on how well made the tyre is; in the case of a M+ there is a coil of steel wire that is inside the tyre bead, normally about three turns. The ends of this are (amazingly) only secured by virtue of the fact that during the tyre moulding process, rubber infuses the tyre bead and this bonds the turns together so that the coil doesn't just unwind.  However


a) if the rubber hasn't infused fully and/or

b) if the tyre flexes in the bead area repeatedly (which can happen if the tyre is run too soft for example, or refitted repeatedly) and/or

c) if the bead sees an abnormally high tension force (which happens if the tyre blows off the rim)

then the tyre bead wire can start to  unwind and render the tyre a slacker fit on any rim.

Bottom line; the tyre can start to blow off the rim for any reason but once it has blown off the rim a few times it may just carry on doing so.

So it is possible that the tyre was a bad fit from the start, and that they tyre wouldn't have worked on any rim. From your description of it, it certainly wouldn't work now. However in view of the fact that I have seen this exact happenstance before, I think it is quite likely that part or all of the problem is caused by the rim, in that tubeless rims like the Mavic one (which is UST compatible) have little or no lip on and this seems to cause problems when fitting M+ tyres especially.

cheers