Tire/Tube Came Off Rim
(PeteCresswell)
heard of "Samson Champion".
Put one of the WTB 55/55 Mutano Raptors that I've been using for
years with no problems on it.
Rim brakes.
Going down a fairly steep hill at (thank G-d!!) a fast walking
pace and BAM!... all-of-a-sudden the rim is riding on dirt and
the tire tube are all squished up. Tube still has air in it, but
not for long since the valve stem got ripped out...
Post-mortem, I couldn't find any damage at all to the tire and
I'm 100% sure it had plenty air in it.
One of the pads was at an angle, but since there was no mark on
the sidewall, I think it got twisted when the tire/tube came off.
I've been riding fat tires since 1983. Had dozens and dozens of
flats and one blowout... but never, ever anything like this.
Can anybody speculate on what happened?
I've got a suspicion, but I'll keep it in reserve so as not to
pollute the answer space.
--
PeteCresswell
Tom Sherman °_°
I blame global warming. ;)
--
Tom Sherman - 42.435731,-83.985007
I am a vehicular cyclist.
Peter Howard
"(PeteCresswell)" <x...@y.Invalid> wrote in message
news:77jfj5d93abp9trn1...@4ax.com...
No *useful* bites yet so I'll kick off. That WTB Mutano is quite a wide tyre at
2.4". Is your obscure and probably Chinese rim no less than 25mm wide? Does it
actually have a hooked edge? Is it measurably undersized in diameter?
Local kid had 2.35" Maxxis tyres mounted by LBS on rims of 19c width. Thought
that was asking for trouble and he got it with beads popping off and tubes
bulging out obscenely if tyre was either over or under inflated. LBS either
don't know or don't care which is why I avoid them.
PH
(PeteCresswell)
>Is your obscure and probably Chinese rim no less than 25mm wide? Does it
>actually have a hooked edge? Is it measurably undersized in diameter?
>Local kid had 2.35" Maxxis tyres mounted by LBS on rims of 19c width. Thought
>that was asking for trouble and he got it with beads popping off and tubes
>bulging out obscenely if tyre was either over or under inflated. LBS either
>don't know or don't care which is why I avoid them.
That pretty much describes my scenario: 19mm width. That is
definitely less than Schwalbe's recommended width for Mutano
Raptors, although my other rims are about that width (maybe even
a hair less) and I've had no problems at all.
My suspicion is that the no-name rim is undersized. I can't get
a precise measurement bco the hub/axle getting in the way of the
tape.
I tried putting two wheels side-by-side and laying a level across
the rims, but they came up apparently level.
OTOH I have this 1.25" cross tire that's been on the shelf for
over a year after I found out that it took three tire irons, a
few bruised knuckles, and a lot of strong language to get on and
off my regular rims. Turns out that I can mount that tire on
the no-name rim with my bare hands and get it off just as easily
as I can the Mutano Raptors off of my regular rims. To me
that's a slam-dunk: the no-name rim is smaller.
Before this, I had no clue about rim width vs tire size. Now I
know. I consider myself *really* lucky not to have a
catastrophic crash bco my ignorance.
--
PeteCresswell
mike.a...@gmail.com
<deleted>
> My suspicion is that the no-name rim is undersized. I can't get
> a precise measurement bco the hub/axle getting in the way of the
> tape.
>
> I tried putting two wheels side-by-side and laying a level across
> the rims, but they came up apparently level.
>
> OTOH I have this 1.25" cross tire that's been on the shelf for
> over a year after I found out that it took three tire irons, a
> few bruised knuckles, and a lot of strong language to get on and
> off my regular rims. Turns out that I can mount that tire on
> the no-name rim with my bare hands and get it off just as easily
> as I can the Mutano Raptors off of my regular rims. To me
> that's a slam-dunk: the no-name rim is smaller.
>
> Before this, I had no clue about rim width vs tire size. Now I
> know. I consider myself *really* lucky not to have a
> catastrophic crash bco my ignorance.
> --
> PeteCresswell
Speaking of which, 700C size has a 622 MM bead diameter, and 26 in has
a 630MM bead diameter.
Is there a standard distance from the bead hook to the actual outside
of the rim?
In 2005 I was at hilly hundred in Bloomington IN and I was trying to
help a guy get these knobby tires on the rim and the bead was barely
fitting inside the outermost edge of the rim. Was that a 700C rim
instead? It did seem the tire bead was about 1/4 in high on from
where the bead sits all the way around. 25.4 / 4 MM = 1/6 inch
Peter Howard
"(PeteCresswell)" <x...@y.Invalid> wrote in message
Tsk. Double whammy for you. Empirical evidence suggests undersize rim *and*
definitely narrower than recommended. The Velocity rims I have on my 26"
wheelsets are all either 23c or 25c so I haven't encountered spontaneous bead
ejection myself. You might have got away with one of the problems but not both.
You could try a narrower tyre while testing and if the electric power works well
for you you'll need to invest in a wider rim and possibly spokes so you can use
your tyre of choice.
Just waiting for an Ozland discount electronics house to re-stock a quite cheap
e-bike wheel kit so I can try one. My work gives me access to any number of used
12v 24Ah SLA batts that have failed fairly stringent capacity tests so there
won't be any investment in batteries.
I will be abused by some for recommending Wikipedia as an authority on anything
but here's their page on ISO 5775, the bike tyre standard developed by ETRTO.
http://en.wikipedia.org/wiki/ISO_5775#Rims
Right near the beginning is a handy table I have tacked up in my workshop that
gives nominal tyre section widths versus standard rim widths.
PH
Kerry Montgomery
(Pete)
You could measure the circumferences of your two rims and compute diameters.
Kerry
Michael Press
<bc67209f-6db4-495e...@j19g2000yqk.googlegroups.com>,
"mike.a...@gmail.com" <mike.a...@gmail.com> wrote:
> Speaking of which, 700C size has a 622 MM bead diameter, and 26 in has
> a 630MM bead diameter.
Incorrect.
Nominal 26 inch has a 559 mm bead diameter.
--
Michael Press
thirty-six
> Before this, I had no clue about rim width vs tire size. Now I
> know. I consider myself *really* lucky not to have a
> catastrophic crash bco my ignorance.
Gap between rim walls should be around 0.7 of tyre section.
mike.a...@gmail.com
> In article
> <bc67209f-6db4-495e-9ae3-a13ee285f...@j19g2000yqk.googlegroups.com>,
>
> "mike.a.sch...@gmail.com" <mike.a.sch...@gmail.com> wrote:
> > Speaking of which, 700C size has a 622 MM bead diameter, and 26 in has
> > a 630MM bead diameter.
>
> Incorrect.
> Nominal 26 inch has a 559 mm bead diameter.
>
> --
> Michael Press
630 mm is 27 inch tires, per Sheldon's site. My mistake.
And since it was a knobby, it was not a 700 or a 27.
(PeteCresswell)
>(Pete)
>You could measure the circumferences of your two rims and compute diameters.
I've avoided responding to this because I was so embarrassed not
to have thought of that -)
Thanks.
--
PeteCresswell
(PeteCresswell)
>
>Gap between rim walls should be around 0.7 of tyre section.
Mutano Raptor 55/55, then should have gap between rim walls =
approx 38.6?
--
PeteCresswell
thirty-six
> Per thirty-six:
>
>
>
> >Gap between rim walls should be around 0.7 of tyre section.
>
> Mutano Raptor 55/55, then should have gap between rim walls =
> approx 38.6?
At least 1/2 I think which would be 28mm A steel rim I have, I
believe meant for 1.1/8 and 1.1/4" tyres (32/28mm) is 20mm between the
walls. So perhaps this 0.7 is for the smallest section tyre. Let's
guess that it was also suitable for 1.3/8" (35mm) then the 20mm
between walls is 0.57 of tyre section, taking this to your 55mm(?)
then the narrowest section between walls would be around 31mm. So
I'd guess that somewhere between 28 and 32mm would be the narrowest
rim gap I could use with confidence on such a large section tyre.
(PeteCresswell)
>
>At least 1/2 I think which would be 28mm A steel rim I have, I
>believe meant for 1.1/8 and 1.1/4" tyres (32/28mm) is 20mm between the
>walls. So perhaps this 0.7 is for the smallest section tyre. Let's
>guess that it was also suitable for 1.3/8" (35mm) then the 20mm
>between walls is 0.57 of tyre section, taking this to your 55mm(?)
>then the narrowest section between walls would be around 31mm. So
>I'd guess that somewhere between 28 and 32mm would be the narrowest
>rim gap I could use with confidence on such a large section tyre.
Check out Schwalbe's page (the rim width stuff is near the
bottom): http://www.schwalbetires.com/tech_info/tire_dimensions
--
PeteCresswell
thirty-six
That's all assuming the rim is a hooked edge and the tyre also
contains beading, I think. My observation was based on simpler tyres
and rims which is more restrictive.