Come on then brainiacs, give me a fix for this

[mickle]

My new-to-me 1990 Orange Clockwork has a problem. The tyres spin in the rims under braking. Ive taken it for precisely two little test rides up the road and back, nothing radical or remotely challenging. And when i get back both valves are at 45 degrees, evidence that the tyres are slipping on the rim under braking. Ive tried just wiping the surfaces with degreaser but this hasn't helped at all.

Rims are Mavic 231s. Tyres are Panaracer Rampage 2.1 and 2.3 with kevlar bead.

Got any ideas?

 

[Gunk]

What pressures are you running?

 

[sevenfourate]

100% sure tyres are correct size for rims - and of the right type for those rims ? Ie: Is the bead of the tyre seating and locking into the rim properly. As clearly it can’t be from what you’re saying……

 

[mickle]

What pressures are you running?

I dunno, the guage broke. Higher pressure might fix the problem, but would be too harsh to ride.

 

[mickle]

100% sure tyres are correct size for rims - and of the right type for those rims ? Ie: Is the bead of the tyre seating and locking into the rim properly. As clearly it can’t be from what you’re saying……

Rims and tyres are 559 - 26inch. The bead seats ok, the tyres run straight and true.

 

[mickle]

I run inner tubes and always talc the inside of my tyres. I wondered if this might be contributing to the problem so i cleaned off the relevant surfaces. But it didnt stop the slippage.

 

[Drago]

Alloy rims? Dismount the tyres and clean the, rough up the mating surface on the inside of the rim try again.

Useless fact - this used to happen under acceleration on early versions of the MG Metro turbo.

 

[Punkawallah]

Are the tyres and rims both ‘clinchers’?
https://www.sheldonbrown.com/tire-sizing.html

 

[lazybloke]

This doesn't help Mickle, but I've also had this problem on a borrowed bike that had solid tyres. I could especially feel the slippage when trying to pick my way down a very steep muddy bridleway (with brakes on hard)

Weird, and quite alarming.

 

[Big John]

New one on me. I was working on a 2.1 tyre the other day and that's one beast of a tyre.....or at least it is to me, a roadie. What's the inside width of the rim? I can only summise that the rim and tyre size aren't compatible but I'm only guessing. Is the tube the right size for the tyre? The rim I was working on was insanely wide, by the way. Not quite big enough for a fat bike but super wide for a 2.1.

Edit: The link above from Punkawallah is spot on and should help solve the mystery 👍

 

[Ajax Bay]

Mavic 231 rim 26" (559 x 17) and Tyres are Panaracer Rampage 2.1/2.3 (559-54/57)
This is well over Sheldon Brown's 2 max multiple (tyre width / inner rim width)
but (compatibility)
This combo is entirely normal for wheels/rims of this age: the whole 'wider rim' thing is 'new': 17s mounting 2.1s was (and is) entirely normal.
Tube, and pressure difference (at riding levels) will have minimal effect on this.
I think OP has taken the straightforward steps: clean off any talc. I wonder whether in cleaning the hook(part of rim) with degreaser they have actually been too well cleaned, lubricated even.
Need to increase the coefficient of friction between the bead and the hook. Having never had this problem with an inflated tyre I don't have a recipe (ETA: but @Yellow Saddle has: see below). But inside of the bead as well as the rim itself is a site for possibilities (not anything vulcanising): what about smearing some slime all round the bead?
Reasonable to assume the rim-tyre combo is on the loose side so maybe try another tyre (similar width) to see if that exhibits the same annoyance.

ETA: I should be out riding but it's too cold (history of frostbitten digits) so "just Sunday morning musing".

 

[Dogtrousers]

Maybe you are just unlucky.

Just as you can get some tyres that are nominally the right size but which are incredibly hard to fit while others are ok, so maybe you're unlucky and have tyres at the big end of the variation of how manufacturers choose to apply sizing numbers.

Using the same nominal size from a different manufacturer might be a different story.

None of that is from practical experience. Just Sunday morning musing. And it would be a pretty expensive theory to test. "Ok I've bought four new tyres and that's not the problem."

 

[bikingdad90]

The rim isn’t by any chance bowing outwards ever so slightly and no longer aligned so the bead slips?

 

[Yellow Saddle]

Belt dressing on the beads.

 

[si_c]

Take off the tyres, thoroughly degrease both the rims and the tyres - remove the rim strip if possible. Put new rim tape on and pump thre tyres up to the correct pressure - I'm guessing that's probably around 45-55psi.