Rims and tire width

[Thomas Carstens]

I have a Hunquapillar on order and I'm going to build it up with a
bunch of parts I have accumulated. What I'm wondering about is
whether I can/should use the wheels I have. They're Mavic MA 3's 36
spokes and Shimano XTR M900 hubs. They're really nice wheels and the
hubs are fantastic but I would like to mount 40mm or larger tires.
The bike shop people say I shouldn't, but the argument isn't too
compelling and I have a set of wheels w/ Mavic Open Pro and 38mm tires
and it doesn't seem to be a problem, but what do I know, maybe there
is. I just don't have any other use for the wheels except on the
Hunqupillar and I would rather not dismantle them in order to use the
hubs to build new wheels. I was hoping that some of the members on
the list might weigh in on this. Thanx, Tom

[Smitty-A-Go-Go]

Sounds like a pretty skinny rim for 40+mm tires.  Even if it works it's probably less than ideal. If I were in your shoes I might give it a go and take it easy for  a while. 

[Mojo]

I have put 44mm knobbies on MA3 rims, and it seemed to work fine. Perhaps with rims of this width, you must keep the tire pressure a bit higher than you would have to with a wider rim. But like you, I didn't experientially understand the advice that you must use a wider rim with a wider tire.

[RonLau]

Tom,

Rich sold me a set of wheels with DT TK540 rims on it.  It is 24.5mm wide and it is design for 29'er.  It is 540g per rim, hence the name TK540, not the lightest rim for road use but light enough. 

The best part for this rim is a Conti 4 seasons 700x28 measures 28mm, that is a shock for me.

Ron

[Phil Bickford]

I can report running 2.1" (53.3cm) Quasi Moto on a 19.5mm width
Velocity 650 Aero with out trouble, but I've had the "almost-rolled-
off-rim" feel to a 32mm Pasela TG mounted on a 19.5mm Mavic rim.

I believe it's all in the pressure used.

I'd say run what you have and keep the pressure above 50, unless the
MA40 has a known problem with tire roll off. I've no experience with
that rim.

Phil B

[PATRICK MOORE]

I ran 1.95 knobbies on 19 mm (outside) Sun and Trek semi-aero rims with no problems; again, as long as you kept the pressure high enough. I too found 32 mm (559) Paselas very sensitive to pressure on narrow rims -- one reason I don't care for them.

My former 29er came with 24.5 mm Alex rims and 60 mm Weirwolfs.

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[Philip Williamson]

I think you should try them as they are with fat tires. If they feel
funny or don't inspire confidence, try to get wider rims with a
similar ERD to the MA-3, and move them over, spokes and all.

I rolled a tire on Sunday, a 60mm Big Apple (really 53mm wide) on a
WTB SpeedDisc wheel, but I have no plans to change the front tire. I
think it's a fluke.
http://www.biketinker.com/2011/projects/gravel-road-test-ride/

I did balk at putting those tires on narrow Cold Fusion rims, though.
The dyno wheel I built for that bike works better on another one
anyway.

Philip

Philip Williamson
www.biketinker.com

[PATRICK MOORE]

53 mm!! That **is narrow**!!! My 60s measured 65 mm on a 45 mm rim and easily 59 on a 24.5 mm rim. What gives?

I do think they stretch with use -- problem is, if you pump them only to sub-20 lb pressures, as I do, that can prolong the stretching.

53!!!! Are you sure you don't have the 50s and not the 60s?

On Tue, Dec 13, 2011 at 7:09 PM, Philip Williamson <philip.w...@gmail.com> wrote:

I rolled a tire on Sunday, a 60mm Big Apple (really 53mm wide) on a
WTB SpeedDisc wheel, but I have no plans to change the front tire. I
think it's a fluke.
http://www.biketinker.com/2011/projects/gravel-road-test-ride/

[Thomas Carstens]

Thanks for the help! Since yesterday I've discovered an interesting
article on the Schwalbe tires web site. http://www.schwalbetires.com/tech_info/tire_dimensions#rim
According to them, the European Tire and Rim Technical Organization
Standards have changed due to a lot of experience with MTBs using
narrow rim/wide tire combos with no negative consequences. They have
a chart which differs from others I've seen. Also, they seem to
suggest that, if anything, on a narrow rim wide tire setup the tire
pressure should possibly be reduced.
Tom

[PATRICK MOORE]

Very interesting -- it is a change from other advice I've heard. But you've got it exactly backward (and Schwalbe says the opposite: read more carefully) about lower pressure on a narrow rim: you need higher pressures on a narrower rim, all else equal.

I know that one big benefit of wide rims (as Schwalbe notes) is that they give a fat tire more stability so that you can run it at lower pressures: I run my 60 mm BAs as low as 12/16 on dirt on 45 mm rims with no adverse consequences (I'm 175). I've even run them this low on pavement: apart from a bit of bounce, no real problem. Flop in cornering is hugely reduced compared to the same tire and pressure on a 25 mm rim.

Note though that a given pressure on a wider rim will feel "harder" than the same pressure on a narrower rim, doubtless due to that same, better sidewall support; this is my experience with the BAs and the 45 mm versus 25 mm rims.

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[Philip Williamson]

I'm not sure of anything except that I wish I had 45mm rims.

Philip (nothing exceeds like excess) Williamson

On Dec 13, 8:20 pm, PATRICK MOORE <bertin...@gmail.com> wrote:
> 53 mm!! That **is narrow**!!! My 60s measured 65 mm on a 45 mm rim and
> easily 59 on a 24.5 mm rim. What gives?
>
> I do think they stretch with use -- problem is, if you pump them only to
> sub-20 lb pressures, as I do, that can prolong the stretching.
>
> 53!!!! Are you sure you don't have the 50s and not the 60s?
>
> On Tue, Dec 13, 2011 at 7:09 PM, Philip Williamson <
>

[PATRICK MOORE]

45s are skinnies; get the latest 100 mms from Surely.

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[Thomas Carstens]

That's true except they also indicate a bit further on that in order
to prevent "excessive stress on the rim" when the rim is narrow and
the tire is wide, they recommend pressures less than max. They do say
a wider rim "often" provides additional stability and that a
"slightly" reduce pressure can be ridden before stability becomes
"spongy". It's interesting that they use words such as "slightly"
and "spongy". Before I was concerned that there might be some danger
in the narrow rim/wide tire setup, but now I'm thinking that it might
be more a question of feel or possibly ride quality. Anyway, I'll try
my MA 3's with 40 or 42's and see what happens.
Tom

On Dec 13, 10:38 pm, PATRICK MOORE <bertin...@gmail.com> wrote:
> Very interesting -- it is a change from other advice I've heard. But you've
> got it exactly backward (and Schwalbe says the opposite: read more
> carefully) about lower pressure on a narrow rim: you need higher pressures
> on a narrower rim, all else equal.
>
> I know that one big benefit of wide rims (as Schwalbe notes) is that they
> give a fat tire more stability so that you can run it at lower pressures: I
> run my 60 mm BAs as low as 12/16 on dirt on 45 mm rims with no adverse
> consequences (I'm 175). I've even run them this low on pavement: apart from
> a bit of bounce, no real problem. Flop in cornering is hugely reduced
> compared to the same tire and pressure on a 25 mm rim.
>
> Note though that a given pressure on a wider rim will feel "harder" than
> the same pressure on a narrower rim, doubtless due to that same, better
> sidewall support; this is my experience with the BAs and the 45 mm versus
> 25 mm rims.
>