psi ratings for wheels?

Katharine & Paul said:

Just read on cyclingnews.com about a lightweight wheel, in which they state
to only inflate tyres to 120psi (Williams wheels)

The light wheels I use are some Velocitys - about 10 years old now, but
still very light even by todays standards.

I have always inflated conti tyres up to 140-150psi. I have recently bought
cont GP supersonics which can go up to 170psi

Anyone heard of rim damage caused by a tyre too strong for the rim? Should I
be concerned about what rim I put the GP supersonic on?????

Never heard of a rim psi recommendation before. Any basis to this?????

This subject recently came up on the Bike North email chat

Quoted post said:

The rim failure is caused by one or both of:

- braking surfaces wearing thin over the life of the wheel rim
- high pressures being used in the tyre.

In my case it was both.

Most rims have a limit to tyre pressures and this varies with rim model and maker. Some are higher than others, especially for 26 inch wheels, which are built to run lower pressures than 700C. I have just installed 26 inch Mavic rims which are rated to 110psi for 1 inch tyres but only 48psi for 2.75 inch tyres. Many rims are rated lower than this. On the rim that failed, I was just running 80 psi, but given the rim wear, that was too much.

and

Quoted post said:

> > I have just installed 26 inch Mavic rims which are rated to

Quoted message said:

Quoted message said:

110psi for 1 inch tyres but only 48psi for 2.75 inch tyres.

Quoted message said:

Doug, where on earth do I find this info on the specs?
Have never seen this mentioned anywhere in the specs?

Printed on the rim label. :-)))

Actually is it on the Mavic web site as well.

e.g. Rims:
Open Pro = tinyurl.comy5bvmaOpen ↗
CXP 33 = tinyurl.comy82agbOpen ↗
Xc717 = tinyurl.comy8rsxgOpen ↗

e.g. Wheels:
Ksyrium Elite = tinyurl.comyy2koxOpen ↗
Crossland = tinyurl.comyyogt9Open ↗

700C rims are built to take higher pressures. Not sure about other brands as I haven't checked.

The Xc717 has a nifty warning device on rim wear. They have ground half the rim away at two points from the inside. So when I see two holes appear, near the label, then I know the rim is starting to get a bit thin. I hope it hasn't weakened the rim too much. ;-)

Quoted message said:

I too am winding back the pressures I put on my 26
inch tyres, found that the rims tended to
self-destruct rather quickly at anything more than
80psi with even a 1 inch tyre, and have had no
problems so far (touch wood) with running 55-60psi
with a 1.4/5 inch tyre.

I had been running my 1.4 front and 1.5 rear @ 70 psi for the last couple of years. No problems. With the better rims, I have just shifted to 1.25 @ 80 (max 103) and 1.4 @ 80 (max 88). Stay tuned.

Ride and smile,
Doug

[acknowledgements to Bike North BUG chat list and its members]

Refer to rim manufacturers sites or contact manufacturer/distributer/LBS

Mike

Katharine & Paul said:

The light wheels I use are some Velocitys - about 10 years old now, but
still very light even by todays standards.
?

Just about all aluminium rims will easily handle 150psi, unless the braking surface is well worn, or they're some funky new super lightweight thing. Before I realized that about 120psi is the maximum you'd ever need on the road, I used 150 to 160psi in my tyres for YEARS without a problem, on rims such as Velocity, crappy old Arayas, Mavic Open Sups, CD4s, Open Pros, CXP33s, CXP30s, Rigida DP18s........well, that's about it.

The Mavic recommendations are just vague guidelines -- isn't it odd that ALL their rims, from the Kysrium ES right down to the CXP22 have the same pressure recommendations? 🙂

I only once blew a rim but that was because the braking surface was worn right down.

You really don't need 140psi on the road, unless, maybe, you're like 120kg, or you're using tubular tyres.

Quoted message said:

You really don't need 140psi on the road, unless, maybe, you're like
120kg, or you're using tubular tyres.

I'm nowhere near 120kg! Actually, I'm about half that (61kg).

I have always trained on about 100-120 (I use the cheapest tyres I can get
for training), but pumped a good set up to 140 for racing. Pump in a bit
less than that if the road surface is a bit rough. I just find the tyre
seems to roll a bit better. Whether this is perception or reality I'm not
really sure though!!

Quoted message said:

--
531Aussie

Katharine & Paul said:

Quoted message said:

You really don't need 140psi on the road, unless, maybe, you're like
120kg, or you're using tubular tyres.

I'm nowhere near 120kg! Actually, I'm about half that (61kg).

I have always trained on about 100-120 (I use the cheapest tyres I can get
for training), but pumped a good set up to 140 for racing. Pump in a bit
less than that if the road surface is a bit rough. I just find the tyre
seems to roll a bit better. Whether this is perception or reality I'm not
really sure though!!

Do you notice any loss of tyre grip when braking and cornering using your
highest pressures?

Cheers,

Vince

Katharine & Paul said:

I have always trained on about 100-120, but pumped a good set up to 140 for racing. Pump in a bit
less than that if the road surface is a bit rough. I just find the tyre
seems to roll a bit better. Whether this is perception or reality I'm not
really sure though!!

yeah, it's just perception; a tyre feels fast when it's rock hard, but the 'buzzing' is potentially slowing you down because each little bump is moving you slightly upward instead absorbing the bumps and letting you move forward. Cornering is also heaps better on slightly lower pressures. It's hard to say what your exact pressure should be, but I'm sure some on here would say that even 100/90 would suit you!! :eek: 🙂 I'm a 90kg masher, and I never use any more than 130/115, but usually 120/110

I was the worst culprit for high pressures. I always used 20mm tyres and pumped them up as hard as I could. I was stubborn about reducing pressure. I did this for probably 15yrs!! :p. The guys at the bike shop once put a pressure guage on my tyres, and they were 165!!! CRAZY. One day I blew a tyre, and needed one desperately, but the nearest shop had no 20mm tyres! Oh no! 🙂 So, I put a 23mm tyre on the front and I couldn't believe how good it was.

Over the next year i gradually weaned myself off high pressures and got rid of all my 20mm tyres

This is a bit off-topic but how long would one expect a rim to last
anyway (or have I just asked "how long is a piece of string?"? 2000km?
5000km?

Are there warning signs? How thin can the rim get before you would
recommend replacing it?

Vincent Patrick said:

Katharine & Paul said:

Quoted message said:

You really don't need 140psi on the road, unless, maybe, you're like
120kg, or you're using tubular tyres.

Quoted message said:

I'm nowhere near 120kg! Actually, I'm about half that (61kg).

Quoted message said:

I have always trained on about 100-120 (I use the cheapest tyres I can get
for training), but pumped a good set up to 140 for racing. Pump in a bit
less than that if the road surface is a bit rough. I just find the tyre
seems to roll a bit better. Whether this is perception or reality I'm not
really sure though!!Do you notice any loss of tyre grip when braking and cornering using your

highest pressures?

Cheers,

Vince

Bugbear said:

This is a bit off-topic but how long would one expect a rim to last
(or have I just asked "how long is a piece of string?"? 2000km?
5000km?Are there warning signs? How thin can the rim get before you would
recommend replacing it?

when the braking surface is worn you can feel, and even see, the "concavity". Most new rims have wear indicators. Don't worry too much, because the wear is easy to spot

The lifespan mostly depends on the amount of braking, but more so, the amount of braking in wet weather. When you brake in the wet and hear the 'sandpapery' sound that the pads make on the rim, this REALLY chews up the rim. The dirt a grit gets on the pads a seriously files down the aluminium. I've still got "Beach Rd" rims (not much braking on Beach Rd 🙂)that are over 15 years old, but I reckon I chewed through a front Mavic CXP33 in 6 months of hard commuting in [censored] weather

531Aussie said:

Bugbear said:

This is a bit off-topic but how long would one expect a rim to last
(or have I just asked "how long is a piece of string?"? 2000km?
5000km?Are there warning signs? How thin can the rim get before you
would
recommend replacing it?
when the braking surface is worn you can feel, and even see, the

"concavity". Most new rims have wear indicators. Don't worry too much,
because the wear is easy to spot

The lifespan mostly depends on the amount of braking, but really, the
amount of braking in wet weather. When you brake in wet weather and
hear the 'sandpapery' sound that the pads make on the rim, this REALLY
chews up the rim. In the wet, the dirt a grit gets on the pads a
seriously files down the aluminium. I've still got "Beach Rd" rims (not
much braking on Beach Rd 🙂)that are over 15 years old, but I reckon I
chewed through a front Mavic CXP33 in 6 months of hard commuting in
[censored] weather

To reinforce this, my wet weather training wheels last me around
20,000km or so (Mavic open pro rims) that do a lot of wet weather
descending. My race rims, which do a lot less wet weather work, I
expect to last -considerably- longer, at least until the bling has worn
off them 🙂

Quoted message said:

Do you notice any loss of tyre grip when braking and cornering using your
highest pressures?

Cornering - yes. But I dont pump them that high if I am riding on a tight
course with bumpy corners

Quoted message said:

Cheers,

Vince

I was the same with 20mm tyres.

Bow I use a 20 on the front, 23 on the back. Cycling news reported (by
memory) the ideal combo on Conti's testing was a 19 front, 22 back for the
same pressure. A bit narrower on the front for aerodynamics, but a bit less
rolling resistance for a rear 23.

"531Aussie" <[email hidden]> wrote in
message news:[email hidden]...

Quoted message said:

Katharine & Paul said:

I have always trained on about 100-120, but pumped a good set up to 140
for racing. Pump in a bit
less than that if the road surface is a bit rough. I just find the
tyre
seems to roll a bit better. Whether this is perception or reality I'm
not
really sure though!!yeah, it's just perception; a tyre feels fast when
it's rock hard, but

the 'buzzing' is potentially slowing you down because each little bump
is moving you slightly upward instead absorbing the bumps and letting
you move forward. Cornering is also heaps better on slightly lower
pressures. It's hard to say what your exact pressure should be, but I'm
sure some on here would say that even 100/90 would suit you!! :eek: 🙂
I'm a 90kg masher, and I never use any more than 130/115, but usually
120/110

I was the worst culprit for high pressures. I always used 20mm tyres
and pumped them up as hard as I could. I was stubborn about reducing
pressure. I did this for probably 15yrs!! :p. The guys at the bike shop
once put a pressure guage on my tyres, and they were 165!!! CRAZY. One
day I blew a tyre, and needed one desperately, but the nearest shop had
no 20mm tyres! Oh no! 🙂 So, I put a 23mm tyre on the front and I
couldn't believe how good it was.

Over the next year i gradually weaned myself off high pressures and got
rid of all my 20mm tyres

--
531Aussie

Katharine & Paul said:

Just read on cyclingnews.com about a lightweight wheel, in which they state
to only inflate tyres to 120psi (Williams wheels)

The light wheels I use are some Velocitys - about 10 years old now, but
still very light even by todays standards.

I have always inflated conti tyres up to 140-150psi. I have recently bought
cont GP supersonics which can go up to 170psi

Anyone heard of rim damage caused by a tyre too strong for the rim? Should I
be concerned about what rim I put the GP supersonic on?????

Never heard of a rim psi recommendation before. Any basis to this?????

Extensive discussion of this recently on rec.bicycles.tech
http://tinyurl.com/yn4uvf

531Aussie said:

Just about all aluminium rims will easily handle 150psi, unless the braking surface is well worn, or they're some funky new super lightweight thing. Before I realized that about 120psi is the maximum you'd ever need on the road, I used 150 to 160psi in my tyres for YEARS without a problem, on rims such as Velocity, crappy old Arayas, Mavic Open Sups, CD4s, Open Pros, CXP33s, CXP30s, Rigida DP18s........well, that's about it.

The Mavic recommendations are just vague guidelines -- isn't it odd that ALL their rims, from the Kysrium ES right down to the CXP22 have the same pressure recommendations? 🙂

I only once blew a rim but that was because the braking surface was worn right down.

You really don't need 140psi on the road, unless, maybe, you're like 120kg, or you're using tubular tyres.

American Classic clinchers for example have a 120psi maximum rating as they are a very lightweight rim. I've never needed more that that.

Adam