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I recently sold my Delgado Disc rims (28mm wide) and replaced them with DT Swiss TK7.1 rims (23.6 mm wide). I can't really tell the difference. I have used the same tires on both, Ignitors and Exis, without issue. I have a 29er single speed and ride some rocky trails, some small drops and step ups, etc.

So, why is it so important to get wide rims? All my tires seem fine on the narrower TK's. I think I have some good guesses, but I want to hear the specific reasons and why my 23.6 mm rims are not as desirable as the 28mm rims.
 

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Dirdir said:
I recently sold my Delgado Disc rims (28mm wide) and replaced them with DT Swiss TK7.1 rims (23.6 mm wide). I can't really tell the difference. I have used the same tires on both, Ignitors and Exis, without issue. I have a 29er single speed and ride some rocky trails, some small drops and step ups, etc.

So, why is it so important to get wide rims? All my tires seem fine on the narrower TK's. I think I have some good guesses, but I want to hear the specific reasons and why my 23.6 mm rims are not as desirable as the 28mm rims.
Wider tires can be more stable on wider rims, especially for heavier riders (body weight and riding style).

Some tire treads work better with a more square profile (and some are better with a rounder profile). Or personal riding styles can be more suited to one or the other.

I like most wide tires on narrow rims. The bikes/wheels I ride most (26 and 29) have 22-23mm rims with tires up to 2.6".

Plus the wider rim "should" be stronger but many other variables come in to play there.
 

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Discussion Starter · #3 ·
shiggy said:
Wider tires can be more stable on wider rims, especially for heavier riders (body weight and riding style).

Some tire treads work better with a more square profile (and some are better with a rounder profile). Or personal riding styles can be more suited to one or the other.

I like most wide tires on narrow rims. The bikes/wheels I ride most (26 and 29) have 22-23mm rims with tires up to 2.6".

Plus the wider rim "should" be stronger but many other variables come in to play there.
Seems that rim width is nuanced. I have seen a ton of discussion or comments about rim width on the 29er forum, but not all that much on the other forums. I really did not understand all the fuss. I run Mavic 819 rims on my Turner 5-Spot with some fairly wide tires - Geax Sturdy, Specialized 2.4, etc/. and never had an issue. Indeed, it seems the 819s are highly recommended for all mountain as well as XC riding.
 

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i have an 04 enduro s-works with mavic 317(21.6mm) that i was running panaracer fire xc pros on and tried a set of kenda nevegal 2.35s on. never liked the kendas because they always felt like they were rolling, just felt weird and i was always messing with air pressure trying to get them right, anyway just got my new easton am havoc wheelset(28mm) and threw the kendas on, wow what a difference the tires are way more stable feeling and stick to evrything, big difference in the tires performance
 

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runhuskyrun said:
i have an 04 enduro s-works with mavic 317(21.6mm) that i was running panaracer fire xc pros on and tried a set of kenda nevegal 2.35s on. never liked the kendas because they always felt like they were rolling, just felt weird and i was always messing with air pressure trying to get them right, anyway just got my new easton am havoc wheelset(28mm) and threw the kendas on, wow what a difference the tires are way more stable feeling and stick to evrything, big difference in the tires performance
Nevegals are one of those tires that works best on wider rims.
 

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Agree with what's been said so far.

Wider rims make your tires run wider. Since there's been a shortage of wide 29er tires, this is a nice bonus.

Also, wider rims allow you to run lower pressures. A wide tire with low pressure on a narrow rim tends to squirm a lot, side to side.

francois
 

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Dirdir said:
So, why is it so important to get wide rims? All my tires seem fine on the narrower TK's. I think I have some good guesses, but I want to hear the specific reasons and why my 23.6 mm rims are not as desirable as the 28mm rims.
Who says it's so important?

Ideal rim width depends on where you live (terrain), how and where you ride, as well as what you ride. And all of that has to be lumped together with your past experience and personal preferences. There is no one right answer.

MC
 

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Dirdir said:
Seems that rim width is nuanced. I have seen a ton of discussion or comments about rim width on the 29er forum, but not all that much on the other forums. I really did not understand all the fuss. I run Mavic 819 rims on my Turner 5-Spot with some fairly wide tires - Geax Sturdy, Specialized 2.4, etc/. and never had an issue. Indeed, it seems the 819s are highly recommended for all mountain as well as XC riding.
"All Mountain riding" is a funky new label for cross country riding that isn't racing. And 19mm is a fairly narrow rim. So, the fact that it's called "All Mountain" reveals the inaccurate and misleading nature of the "All Mountain" label, because a 19mm rim is a fairly narrow rim.

If you can run wide tires on a 19mm rim without rolling or blowing one off the rim and without having profile issues, then chances are pretty good that you probably don't ride all that hard, don't corner hard, don't go very fast. That's where the discussion comes back to "All Mountain" being a code word for "cross country". There's nothing wrong or negative about not riding hard in tough terrain. In the world of snowboarding and downhill skiing most who ride snow are intermediates. Same in MTB riding as far as I'm concerned. To my mind, "All Mountain" is a label for those who ride cross country but feel insecure when they compare themselves to DH racers or "freeriders", as if they are embarrassed to admit they're just intermediate-level riders. I don't see any other reason to create a new label for cross country riding.

As to the rim width, I wouldn't expect to see a difference moving from 28 mm to 23.9 mm unless you're talking about a 2.5 or 2.7 DH tire.

And in the end it really depends more on riding style, riding terrain, and the bike and tire choices you make.

I found pretty huge differences in my tires' profiles and performance after switching from Sun 18mm front rim & Velocity 20mm rear rim to Salsa 28mm Delgado Disc rims. The tires in question were Nevegal 1.95 rear, 2.1 front and Minion 2.35 rear and front. The Nevegals took on a nicer profile and performed much better at all pressures. The Minions were a lot less squirmy at any pressure below 40 psi.

Also, as a last bit -- don't forget that some mfrs measure outside width, and some measure inside width. The measurement that affects tire profile is the bead-to-bead width inside the rim.
 

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pablo_b said:
"All Mountain riding" is a funky new label for cross country riding that isn't racing. ... There's nothing wrong or negative about not riding hard in tough terrain. In the world of snowboarding and downhill skiing most who ride snow are intermediates. Same in MTB riding as far as I'm concerned. To my mind, "All Mountain" is a label for those who ride cross country but feel insecure when they compare themselves to DH racers or "freeriders", as if they are embarrassed to admit they're just intermediate-level riders. I don't see any other reason to create a new label for cross country riding.
Huh? What?
 

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Discussion Starter · #11 ·
pablo_b said:
"All Mountain riding" is a funky new label for cross country riding that isn't racing. And 19mm is a fairly narrow rim. So, the fact that it's called "All Mountain" reveals the inaccurate and misleading nature of the "All Mountain" label, because a 19mm rim is a fairly narrow rim.

If you can run wide tires on a 19mm rim without rolling or blowing one off the rim and without having profile issues, then chances are pretty good that you probably don't ride all that hard, don't corner hard, don't go very fast. That's where the discussion comes back to "All Mountain" being a code word for "cross country". There's nothing wrong or negative about not riding hard in tough terrain. In the world of snowboarding and downhill skiing most who ride snow are intermediates. Same in MTB riding as far as I'm concerned. To my mind, "All Mountain" is a label for those who ride cross country but feel insecure when they compare themselves to DH racers or "freeriders", as if they are embarrassed to admit they're just intermediate-level riders. I don't see any other reason to create a new label for cross country riding.

As to the rim width, I wouldn't expect to see a difference moving from 28 mm to 23.9 mm unless you're talking about a 2.5 or 2.7 DH tire.

And in the end it really depends more on riding style, riding terrain, and the bike and tire choices you make.

I found pretty huge differences in my tires' profiles and performance after switching from Sun 18mm front rim & Velocity 20mm rear rim to Salsa 28mm Delgado Disc rims. The tires in question were Nevegal 1.95 rear, 2.1 front and Minion 2.35 rear and front. The Nevegals took on a nicer profile and performed much better at all pressures. The Minions were a lot less squirmy at any pressure below 40 psi.

Also, as a last bit -- don't forget that some mfrs measure outside width, and some measure inside width. The measurement that affects tire profile is the bead-to-bead width inside the rim.
The Mavic 819 rims are 23mm wide. I don't know what the 819 stands for, but not 19mm. I disagree with your take on the All Mountain label. Whether one likes it or not, the term All Mountain is commonly used and commonly understood. I don't know why so many people get all hot and bothered by it. My guess is that rather than using it because they are insecure, people just use it because it is there. Simple really. Hell, maybe the bike manufacturers came up with it as a marketing device. Suggesting that people who use it are trying to cover up their insecurities is insulting. As for me, yea, I am an intermediate rider. I might even suck. Many downhillers and freeriders are intermediate riders and/or they suck. But, even though I suck, I wouldn't say that I don't ride hard. I try my a$$ off.
 

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Wide for Clyde

Wide for Clyde - my experience is that narrow rims and larger tires (2.4 and up) are not a good combo for the larger person in that the tires tend to roll sideways on any kind of sidehill unless you run really high pressures. A wider rim lets you ride the same tire at lower pressures w/o any problems. Currently riding Sun Single Track rims (31mm?) w/ Racing Ralph (2.4) and Stans - great combo. Had previously tried same tires on Velociy Cliffhangers (?) and scared myself. Current setup is heavy, but worth it.
 

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Dirdir said:
The Mavic 819 rims are 23mm wide. I don't know what the 819 stands for, but not 19mm. I disagree with your take on the All Mountain label. Whether one likes it or not, the term All Mountain is commonly used and commonly understood. I don't know why so many people get all hot and bothered by it. My guess is that rather than using it because they are insecure, people just use it because it is there. Simple really. Hell, maybe the bike manufacturers came up with it as a marketing device. Suggesting that people who use it are trying to cover up their insecurities is insulting. As for me, yea, I am an intermediate rider. I might even suck. Many downhillers and freeriders are intermediate riders and/or they suck. But, even though I suck, I wouldn't say that I don't ride hard. I try my a$$ off.
not to dredge this up, but I've been doing quite a bit of rim research lately and you're wrong on the Mavic rim width...partially. The 819 IS 19mm wide...the inner dimension (that is how mavic describes it, not outer rim width...) The External width is 23mm. 8 is a number used to describe the level of the wheel; what you or I may consider the quality....a 317 is a lower end rim (and the inner width is 17mm), whereas an 819 is the highest level rim and the inner dimension is 19mm.

This of course is a little confusing as most folks list outer, or Both widths.
 

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Wide rims for low pressure.

I found that on narrow rims, i have to put more pressure than usual for preventing the tire from giving a floating feeling side to side....
 

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Dirdir said:
So, why is it so important to get wide rims? All my tires seem fine on the narrower TK's. I think I have some good guesses, but I want to hear the specific reasons and why my 23.6 mm rims are not as desirable as the 28mm rims.
Wide rims handle big tires better than narrow ones....especially in rocky, rooty and off-cambered terrain.

R.
 

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tozovr said:
not to dredge this up, but I've been doing quite a bit of rim research lately and you're wrong on the Mavic rim width...partially. The 819 IS 19mm wide...the inner dimension (that is how mavic describes it, not outer rim width...) The External width is 23mm. 8 is a number used to describe the level of the wheel; what you or I may consider the quality....a 317 is a lower end rim (and the inner width is 17mm), whereas an 819 is the highest level rim and the inner dimension is 19mm.

This of course is a little confusing as most folks list outer, or Both widths.
I.S.O. rim sizes (the "official" standard) are stated as the bead seat diameter (622mm for 29er rims, 559 for mtb 26") x the inside width, so the XM819 ISO size is 559x19. The A317 size, 622x17.

The outside width for most rims is 6-7mm more than the inside width.

It is easier for consumers to see and measure the outside width but it is the inside width that make the difference for the tire.
 

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Stroganof said:
Wide for Clyde - my experience is that narrow rims and larger tires (2.4 and up) are not a good combo for the larger person in that the tires tend to roll sideways on any kind of sidehill unless you run really high pressures. A wider rim lets you ride the same tire at lower pressures w/o any problems.
Agreed. I went from two fairly narrow sets of rims to the Sun RhynoLite and noticed immedialey that my sidewalls seemed less flexy. I could also run lower pressures, but I ended up not doing so. Clydes need wide.
 

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My opinion only no scientific studies.

one of the benifits with a 29er wheel is a bigger contact patch.

So wouldn't the contact patch be greater on a wider rim?

I would think that a narrower rim ballons the tire making it,
more rounder and narrower tire contact patch and make it mostly on the center of the tire.
 

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Normbilt said:
My opinion only no scientific studies.

one of the benifits with a 29er wheel is a bigger contact patch.

So wouldn't the contact patch be greater on a wider rim?

I would think that a narrower rim ballons the tire making it,
more rounder and narrower tire contact patch and make it mostly on the center of the tire.
Air pressure is what affects the size of the contact patch. At the same pressure and load the area (size) of the CP is the same no matter the diameter or width of the tire or width of the rim. The latter 3 factor affects and change the SHAPE of the contact patch, just not the size.
 
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