# HED Ardennes PSI limit? Why?



## dmanthree (Aug 22, 2014)

Curiouslty question: why is the HED Ardennes, an allow rim, limited to 90 PSI? Seems low for alloy.

PS: not looking for a lecture on the benefits of lower tire pressure.


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## Jay Strongbow (May 8, 2010)

Good question. I think it's because of the tubeless compatibility and that's about par for the course for that.

I had those rims before they were tubeless compatible. I'm pretty sure I would have seen such a limit before buying them if it existed when they were not tubeless compatible. And I routinely used 95-100 with no problems. And I think the only change since then is they are tubeless compatible unlike what I had a few years ago.

So that's my guess.

Add another reason to not like this road tubeless thing if my guess is correct. I use 90 now and would rather not be right at any limit so scratch another good rim off the list.


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## November Dave (Dec 7, 2011)

The brake tracks start to bow out if you get much beyond that, and they want to leave a healthy safety margin against inaccurate pumps, people leaving wheels in hot cars, etc. 

We measured a bunch of modern alloy and carbon rims a while ago and they all start to bow out somewhere near 90 or 100, on the order of .1mm or so, and then you go up past a certain threshold (that varies from model to model and brand to brand) and all of a sudden WHOMP the brake tracks are .25mm wider than they are with no tire. Carbon you can tell when you've really hit the limit because "crack."

As for why, I'd say it's more width than tubeless compatibility. The tubeless tire bed bridges the brake tracks better than non-tubeless tire bed. And the limit is likely more relevant for tubeless tires than tubed tires. And the HED site shows a 100 psi limit for C2, which is as I'd remembered it (just got curious and checked).

Somewhere in the past we did a blog post about this which someone can probably find.


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## dmanthree (Aug 22, 2014)

November Dave said:


> The brake tracks start to bow out if you get much beyond that, and they want to leave a healthy safety margin against inaccurate pumps, people leaving wheels in hot cars, etc.
> 
> We measured a bunch of modern alloy and carbon rims a while ago and they all start to bow out somewhere near 90 or 100, on the order of .1mm or so, and then you go up past a certain threshold (that varies from model to model and brand to brand) and all of a sudden WHOMP the brake tracks are .25mm wider than they are with no tire. Carbon you can tell when you've really hit the limit because "crack."
> 
> ...


The set I was looking at was the disc version. I just find this odd, and wouldn't like to have to live within that limit. I frequently ride at higher pressures.


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## November Dave (Dec 7, 2011)

I don’t see how disc or rim brake would change things - substitute sidewall for brake track in what I said. 
Based on your parameters, you should not choose those rims. Simple.


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## dmanthree (Aug 22, 2014)

November Dave said:


> I don’t see how disc or rim brake would change things - substitute sidewall for brake track in what I said.
> Based on your parameters, you should not choose those rims. Simple.


Agreed. Oh, well. Onward and upward. Maybe the Fulcrum Racing 4db will pan out. They look pretty nice.


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## cxwrench (Nov 9, 2004)

I'd guess it has something to do w/ wider tires (28mm and over) and high pressures. I'd guess that inflating a 25mm tire to 90 or above would be no problem, but when the volume increased and you keep the pressure the same problems can happen. Just like a fat bike rim w/ a limit of 25psi.


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## November Dave (Dec 7, 2011)

Absolutely this. Whether you want to go with LaPlace’s Law or Boyle’s Law (both have strength and weakness in applicability here but they are relevant and work out similarly in what they say) a bigger tire at same pressure exerts more casing load which then stresses the tire support/containment mechanism.


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## dmanthree (Aug 22, 2014)

November Dave said:


> Absolutely this. Whether you want to go with LaPlace’s Law or Boyle’s Law (both have strength and weakness in applicability here but they are relevant and work out similarly in what they say) a bigger tire at same pressure exerts more casing load which then stresses the tire support/containment mechanism.


Makes sense, and convinces me that I need to look elsewhere. Appreciate the input!


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## Peanya (Jun 12, 2008)

dmanthree said:


> Makes sense, and convinces me that I need to look elsewhere. Appreciate the input!


/scratches head and ponders lecturing about crazy-high psi freaks...


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## cxwrench (Nov 9, 2004)

dmanthree said:


> Makes sense, and convinces me that I need to look elsewhere. Appreciate the input!


What size tire and pressure are you talking about? How much do you weigh?

And just for the hell of it, here's what Enve has to say about pressure:


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## loxx0050 (Jul 26, 2013)

Dave and cx are on the right track with this (is my reasoning at least too). 

When something is pressurized you have to pay attention to the total loads and forces that are exerted on the portion that is supporting the loads. That is what you design around for the structure to select material types, thickness and add more support if needed (where there is room). A wider tire will have more air volume and more surface area exerting larger total force than a typical older style skinny tire and thin rims (let's say 19mm wide or less are considered narrow rims these days since 24-25mm is becoming more common). 

For example I head a story of a large dome structure (think golf dome sized but an actual building not an inflatable looking thing) where they accidentally pressured the entire interior to about 4psi. Now, while 4psi doesn't sound like much at it still made a large canvas covered door to vent the place cave in due to the pressure. We are taking a large few thousand square foot door that is very wide and tall. Applying a 4psi force across that entire surface area and you have 10000+lbs of force total pushing against it (not designed for that sort of thing as it just keeps the rain, wind and snow out when the door is closed).


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## jmess (Aug 24, 2006)

*Tubes wearing against spoke holes*

Have a set of HED Ardennes disc wheels that I didn't get any docs with. I started out running them with 23 tires and tubes at 100-105 PSI. During a puncture repair I noticed the HED plastic tubeless rim tape (with proper number of wraps) had sunk in around the rim spoke holes and the tubes were deformed and wearing against the spoke holes. The wear on the tubes was worrisome enough that I replaced the rim tape and tubes. So beside what has already been mentioned, tube wear against the spoke holes could be an issue at higher than recommended pressures. I run under 90 now and haven't had the tube wear.


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## dmanthree (Aug 22, 2014)

Peanya said:


> /scratches head and ponders lecturing about crazy-high psi freaks...


I weigh 175# and have found that running about 105 in the back tire and 95 in the front is what works for me. I honestly don't care what anyone else runs; this is what works for me, my weight, my bike, and my riding.


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## dmanthree (Aug 22, 2014)

cxwrench said:


> What size tire and pressure are you talking about? How much do you weigh?
> 
> And just for the hell of it, here's what Enve has to say about pressure:


What Enve wheel is that for? If it's the 4.5 then it has no hooked bead and can't handle higher pressures. Honestly, I don't get that at all.

I weigh 175# and have found that 105/95 is what works for me. And i'd never, ever buy a wheel without a hooked bead since I run tubed clinchers (GP 4000s II).


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## Lombard (May 8, 2014)

dmanthree said:


> I weigh 175# and have found that running about 105 in the back tire and 95 in the front is what works for me. I honestly don't care what anyone else runs; this is what works for me, my weight, my bike, and my riding.


If you have experimented and that is what works for you, who is anybody to judge? Depending on what tire width you are using 95F/105R isn't unreasonable. I run 28mm tires on my road bike, weigh 185# and run 70F/100R as that works for me as I ride more upright. What width tires do you run?

If I were you, I would look at some of DT Swiss's wheelsets to see what they have to offer.

Interesting about wider rims having a lower max PSI. The max PSI listed on the side of my Stan's Rapid 28 mountain rims is 38PSI.


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## ergott (Feb 26, 2006)

Does this mean they don't sell the 23mm rim in wheels anymore? That rim isn't tubeless. I know they still sell them as rims only.

To the OP, what tire size do you run 95/105 at? Be aware that tire size should affect the pressure you run no matter who you are. 95/105 with 23mm tires is entirely different than 28mm tires at the same pressure.


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## Lombard (May 8, 2014)

ergott said:


> Does this mean they don't sell the 23mm rim in wheels anymore? That rim isn't tubeless. I know they still sell them as rims only.


I believe the OP is looking for disc rims. The C2 (not plus) is not available in a specific disc version. Of course, it could still be used with disc brakes, but I'm guessing the OP would rather not have a brake track.


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## ergott (Feb 26, 2006)

Gotcha. See that a few posts later.

My second question still stands.


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## dmanthree (Aug 22, 2014)

Lombard said:


> If you have experimented and that is what works for you, who is anybody to judge? Depending on what tire width you are using 95F/105R isn't unreasonable. I run 28mm tires on my road bike, weigh 185# and run 70F/100R as that works for me as I ride more upright. What width tires do you run?
> 
> If I were you, I would look at some of DT Swiss's wheelsets to see what they have to offer.
> 
> Interesting about wider rims having a lower max PSI. The max PSI listed on the side of my Stan's Rapid 28 mountain rims is 38PSI.


Hi again,

I'm running 25s which work well for me. And yes, I am looking at the DT Swiss offerings. Strange, though, their allow rims are pretty narrow. I may go the custom route with the HED C2 rims.


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## dmanthree (Aug 22, 2014)

*700 x 25*



ergott said:


> Does this mean they don't sell the 23mm rim in wheels anymore? That rim isn't tubeless. I know they still sell them as rims only.
> 
> To the OP, what tire size do you run 95/105 at? Be aware that tire size should affect the pressure you run no matter who you are. 95/105 with 23mm tires is entirely different than 28mm tires at the same pressure.


Agreed on the relationship between tire size and pressure. I'm running Conti GP 4000s II 25s.


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## cxwrench (Nov 9, 2004)

dmanthree said:


> Agreed on the relationship between tire size and pressure. I'm running Conti GP 4000s II 25s.


Personally I go about 85ish rear/75ish front at 170lbs with 25mm tires mounted on a 24mm internal width rim. That said, I wouldn't say 105/95 is crazy high. Generally for any tire I draw the line at around 100psi...if more pressure is needed what you really need is a bigger tire, but if you've messed around with it and decided on 105 I'd only make a half-hearted attempt to change your mind.


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## ergott (Feb 26, 2006)

dmanthree said:


> Agreed on the relationship between tire size and pressure. I'm running Conti GP 4000s II 25s.


That's pretty typical. I'd look at Boyd or Pacenti options for that tire size. Altamont and Forza are great rims. So is Easton R90 SL. You can go stock or custom. 

Sent from my SM-G950U using Tapatalk


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## Lombard (May 8, 2014)

ergott said:


> Gotcha. See that a few posts later.
> 
> *My second question still stands.*


Yes, I agree. That is why I cut it out of the quote I replied to.


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## Lombard (May 8, 2014)

dmanthree said:


> I'm running 25s which work well for me. And yes, I am looking at the DT Swiss offerings. Strange, though, their allow rims are pretty narrow.


Really? I just looked and everything I see is either 18 or 20mm internal width.



dmanthree said:


> I may go the custom route with the HED C2 rims.


You won't go wrong here as long as you don't mind having a brake track on a disc brake setup. Another good choice would be the H Plus Son Archetype. They have a brake track, but it is anodized in the same color as the rim, so you won't notice it very easily.


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## dmanthree (Aug 22, 2014)

Lombard said:


> dmanthree said:
> 
> 
> > I'm running 25s which work well for me. And yes, I am looking at the DT Swiss offerings. Strange, though, their allow rims are pretty narrow.
> ...


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## dmanthree (Aug 22, 2014)

cxwrench said:


> Personally I go about 85ish rear/75ish front at 170lbs with 25mm tires mounted on a 24mm internal width rim. That said, I wouldn't say 105/95 is crazy high. Generally for any tire I draw the line at around 100psi...if more pressure is needed what you really need is a bigger tire, but if you've messed around with it and decided on 105 I'd only make a half-hearted attempt to change your mind.


Disclaimer: my reading is based on the gauge on the pump. It might be reading high, so maybe I'll get a real gauge and check it.


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## Kerry Irons (Feb 25, 2002)

dmanthree said:


> I weigh 175# and have found that running about 105 in the back tire and 95 in the front is what works for me. I honestly don't care what anyone else runs; this is what works for me, my weight, my bike, and my riding.


When you say "works for me" are you saying that you need these pressures to prevent pinch flats or are you saying you like how the tires feel at those pressures? You're not using outrageous pressures but many people at your weight would be running 10 psi lower and thereby getting better tire wear, better traction, and more comfort. If you're getting pinch flats at pressures below what you are running then you should consider wider tires or more careful riding to avoid hitting the things that cause pinch flats.


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## cxwrench (Nov 9, 2004)

Kerry Irons said:


> When you say "works for me" are you saying that you need these pressures to prevent pinch flats or are you saying you like how the tires feel at those pressures? You're not using outrageous pressures but many people at your weight would be running 10 psi lower and thereby getting better tire wear, better traction, and more comfort. If you're getting pinch flats at pressures below what you are running then you should consider wider tires or more careful riding to avoid hitting the things that cause pinch flats.


^This^...word for word. There is no arguing w/ physics.


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## dmanthree (Aug 22, 2014)

Kerry Irons said:


> When you say "works for me" are you saying that you need these pressures to prevent pinch flats or are you saying you like how the tires feel at those pressures? You're not using outrageous pressures but many people at your weight would be running 10 psi lower and thereby getting better tire wear, better traction, and more comfort. If you're getting pinch flats at pressures below what you are running then you should consider wider tires or more careful riding to avoid hitting the things that cause pinch flats.


Ride, feel, and handling. I don't have any problems with pinch flats, so I arrived at my current preference based on ride quality. I've ridden them at pressures from 85 to 110 and landed where I did based on experience.


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## Lombard (May 8, 2014)

dmanthree said:


> I was looking at the PR series, the 1400. Other models do have a wider width and I am looking at them. If I can't get the HED built for discs, I won't go that way. Not worried, there's lots of choices. To muddy the waters I friend has a set of Roval CLX 32 wheels he'll sell me for about $1500. He no longer needs them, and the only have about 500 miles on them. Tempting...


I don't see why you couldn't get the HED C2s built for discs. Whether they will work for disc brakes depends on the hubs you choose. The rims don't care that you won't be using the brake track on them. 

Between the DT Swiss 1400 PR series and the Rovals, I would choose the DT Swiss. That being said, I don't really like the both of these have such a low spoke count for a disc brake wheel set. I would want at least 28 spokes per wheel on a disc brake wheel set and preferably 32. Keep in mind that disc braking puts tremendous forces on your hubs and spokes.

If it were me, I would lace the HED C2s with a pair of Shimano RS770 or White Industries CLD hubs.


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## dmanthree (Aug 22, 2014)

I'm riding wheels with a 24 spoke count now, and pretty much every disc wheel set I see has a 24 count, so I'm not concerned about that. The only exception I've seen is the Reynolds Aero 46db which has (gasp...) a 20 spoke count on the front wheel. I get to try the Rovals before I have to buy them, so I'll give them a shot for a week or two and then decide.


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## Lombard (May 8, 2014)

dmanthree said:


> I'm riding wheels with a 24 spoke count now, and pretty much every disc wheel set I see has a 24 count, so I'm not concerned about that. The only exception I've seen is the Reynolds Aero 46db which has (gasp...) a 20 spoke count on the front wheel. I get to try the Rovals before I have to buy them, so I'll give them a shot for a week or two and then decide.


Gasp is right! I certainly wouldn't do a 20 spoke db wheel. If going with a reliable brand like DT Swiss or HED, 24 is probably OK, but probably won't feel as stable and stiff as a 32 spoke. At least this is what I have noticed from my own experience. 

My point is more that there is no real valid reason to build such low spoke count wheels. If it's weight, you save about 10g per spoke - BFD! So why do so many high end wheels have such low spoke counts? Here is an article definitely worth reading:

Debunking Wheel Stiffness - Slowtwitch.com 
_
"Why, then, don’t they use more spokes? Two words – fashion and weight. Fewer spokes look cool, and look better on-paper to the gram counters. I agreed to keep any official comments off-the-record from all manufacturers in this regard… but all of them had similar answers - sex sells."
_


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## dmanthree (Aug 22, 2014)

Lombard said:


> Gasp is right! I certainly wouldn't do a 20 spoke db wheel. If going with a reliable brand like DT Swiss or HED, 24 is probably OK, but probably won't feel as stable and stiff as a 32 spoke. At least this is what I have noticed from my own experience.
> 
> My point is more that there is no real valid reason to build such low spoke count wheels. If it's weight, you save about 10g per spoke - BFD! So why do so many high end wheels have such low spoke counts? Here is an article definitely worth reading:
> 
> ...


I guess I'll find out next week when I give the Rovals a shot. Very light, 24 spokes per wheel, and no low PSI limit. If not, I give them back and move on. Also, while you make valid points I have to believe the major wheel builders know what they're doing. DT Swiss, HED, Roval, and others all sell db wheels with 24 spokes. I doubt they'd risk their reputation on something so easily addressed.


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## cxwrench (Nov 9, 2004)

dmanthree said:


> I guess I'll find out next week when I give the Rovals a shot. Very light, 24 spokes per wheel, and no low PSI limit. If not, I give them back and move on. Also, while you make valid points I have to believe the major wheel builders know what they're doing. DT Swiss, HED, Roval, and others all sell db wheels with 24 spokes. I doubt they'd risk their reputation on something so easily addressed.


They know the wheels are *flexible* in certain ways but it doesn't really matter because there aren't any rim brake pads to rub against. The wheels are plenty stiff in the vertical plane but the rim will definitely move side to side...it's not really flexing, the low spoke count is letting it move laterally. It doesn't hurt anything, really. 

I might start bugging you about your pressure preference though...I just can't understand why someone would want less ride quality, less traction, and slightly higher rolling resistance.


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## dmanthree (Aug 22, 2014)

cxwrench said:


> They know the wheels are *flexible* in certain ways but it doesn't really matter because there aren't any rim brake pads to rub against. The wheels are plenty stiff in the vertical plane but the rim will definitely move side to side...it's not really flexing, the low spoke count is letting it move laterally. It doesn't hurt anything, really.
> 
> I might start bugging you about your pressure preference though...I just can't understand why someone would want less ride quality, less traction, and slightly higher rolling resistance.


Bug me all you want, but I'm betting my 43 years of experience riding trump your opinion of what I should or shouldn't like.


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## Lombard (May 8, 2014)

cxwrench said:


> They know the wheels are *flexible* in certain ways but it doesn't really matter because there aren't any rim brake pads to rub against.


No brake pads to rub against, true. But there is still a bike frame to rub against. Most road bikes already have a very tight clearance between the chain stays. There is visual evidence of tire rub on my stays when I was using flexier wheels. 



cxwrench said:


> The wheels are plenty stiff in the vertical plane but the rim will definitely move side to side...it's not really flexing, the low spoke count is letting it move laterally. It doesn't hurt anything, really.


For me at least, there is definitely a different feel. A higher spoke wheel feels more stable and confidence inspiring. But that's just me. As the saying goes, YMMV.


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## bubble (May 19, 2007)

dmanthree said:


> Bug me all you want, but I'm betting my 43 years of experience riding trump your opinion of what I should or shouldn't like.


when did you determine your preferred pressure? I used to run the same pressure, but its dropped in the last couple years in response to equipment changes, even with the same tires. (moving from 17->20->25mm rims)

My dad inadvertently made the same change, but still insists on running 100/105psi

How about h son hydras for rims?

just want you to be happy 👬


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## Lombard (May 8, 2014)

bubble said:


> How about h son hydras for rims?


Those have a 20.5mm internal width. The OP should make sure his preferred tire size fits.


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## dmanthree (Aug 22, 2014)

BTW, I lied. The Roval CLX 32 only has 21 spokes on the front wheel. It uses a 2x lacing on the rotor side and straight lacing on the other side. The rear is 24 spokes with a 2:1 spoke count, cluster vs rotor side. I'll give them a shot and see how it goes.


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## shoerhino (Aug 13, 2004)

From HED's blog:

The maximum pressure you should ever need to use on any Hed Plus or BLACK rim is 90 psi (6.2 bar) – even with a narrow 23mm tire. It’s true! We’re not kidding!

That’s not because 100 psi is dangerous for our rim, but because the ideal range is 65-80 psi for a 77kg (170lb) athlete. As a point of reference, the old school method said that higher pressure was always better, with many athletes using 120 psi or more for a 23mm tire.

Let’s look at a specific example to explain why this is the case. A 23mm Continental GP 4000 tire mounted on a rim with an external width of 19mm (an old-school skinny rim) has an air volume of 660ml. The same tire at the same pressure on a 25mm-wide Hed Plus rim has a volume of 958ml. In effect, the same tire is 33% larger on the Plus rim. The actual measured width of the tire grows from 23mm on the skinny rim to about 26mm on the Plus rim. So – it’s not really a 23mm tire anymore.

What are the benefits of using lower pressure? Two key things: Comfort and Speed. A larger tire puts more physical space between your rim and the road. With lower pressure, the bigger tire can compress more to absorb bumps, without having the rim bottom out and hit the pavement (which can damage the rim or pinch-flat the inner tube). The bigger the tire, the lower you can go on pressure. Of course, if you run the pressure TOO low, rim impacts can still happen


https://www.hedcycling.com/blog/road-tire-pressure-for-plus-and-black-wheels/


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## cxwrench (Nov 9, 2004)

Good post:thumbsup:


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## ToiletSiphon (Jul 23, 2014)

Makes me wonder... I changed the tires on my commuter Giant hybrid. 18mm internal width rim, went from 32mm hybrid tires inflated at 65 psi to 28mm road slicks inflated at 80. Changed the rim tape to road rim tape prior to that. Could the narrower tire and added pressure be an issue to the rim itself? I would never have thought.


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## cxwrench (Nov 9, 2004)

ToiletSiphon said:


> Makes me wonder... I changed the tires on my commuter Giant hybrid. 18mm internal width rim, went from 32mm hybrid tires inflated at 65 psi to 28mm road slicks inflated at 80. Changed the rim tape to road rim tape prior to that. Could the narrower tire and added pressure be an issue to the rim itself? I would never have thought.


I wouldn't think you'd have any problems w/ what you're doing.


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## Lombard (May 8, 2014)

ToiletSiphon said:


> Makes me wonder... I changed the tires on my commuter Giant hybrid. 18mm internal width rim, went from 32mm hybrid tires inflated at 65 psi to 28mm road slicks inflated at 80. Changed the rim tape to road rim tape prior to that. Could the narrower tire and added pressure be an issue to the rim itself? I would never have thought.


I have 18mm internal width rims on a road bike which I use 28mm tires on. No problems. If you look at this chart, you will see you are well within acceptable range:

https://dycteyr72g97f.cloudfront.net/uploads/RDR047DPN24S011543/MAN_WXD10000000866S_WEB_ZZ_001.pdf


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