[shiggy]

Found this while thumbing through the '06 WTB product catalog.

In the rim technology section:

WTB 29er
WTB 29er rims have an ETRTO of 622mm diameter and a minimum bead opening of 21mm. Note that the rim width is the defining element separating 29er rims from trekking, hybrid and road racing rims...

That would be about a 27mm outside width.

By this "standard" the only 29er rims (I can think of at the moment) are the Rhyno Lite, Kris Kolm (sp), Salsa Delgado Disc 29er, and the WTB SpeedDisc Trail and Dual Duty FR.

 

[Bigwheel]

This fits in the same category as using a Lefty on anything other than what is recommended by the manufacturer. It is called covering your @$$ legally. I think we all know that narrower rim widths can work used with jurisprudence.

For instance my son rode a Front Exi/Rear Nano on Zipps all summer without any mishaps at all and that was after I found the bike with wider rims on it like this one day when I came home.....

 

[JMKM]

Question of Function, or Marketing?

What do you think it is? I certainly do like the Salsa Delgado 29er Discs for their width, but up until this point most everyone has been running narrower rims like the Delgado, or even road rims like Open Pro's and things of that nature. If a narrower rim is no good for MTB's then why do dozens of rims exist for 26" wheels that are narrower than what WTB is suggesting?

The point here is. Wider rims have always been better for running lower pressures on high volume tires, 2.3's and up. What WTB is trying to do here is help their potential customers clearly identify what rims they have designed for 29ers and what rims they have designed for other purposes. Makes sense from that standpoint, but it doesn't mean that everyone here is in danger because their rims are to narrow. Rims that don't meet this new id from WTB have been working for several years now.

 

[shiggy]

What do you think it is? I certainly do like the Salsa Delgado 29er Discs for their width, but up until this point most everyone has been running narrower rims like the Delgado, or even road rims like Open Pro's and things of that nature. If a narrower rim is no good for MTB's then why do dozens of rims exist for 26" wheels that are narrower than what WTB is suggesting?

The point here is. Wider rims have always been better for running lower pressures on high volume tires, 2.3's and up. What WTB is trying to do here is help their potential customers clearly identify what rims they have designed for 29ers and what rims they have designed for other purposes. Makes sense from that standpoint, but it doesn't mean that everyone here is in danger because their rims are to narrow. Rims that don't meet this new id from WTB have been working for several years now.

The WTB catalog also has a footnote on the 29er tire page to see pages XX and XX for compatible rims.

Not such compatibility disclaimers for any of the 26" tires or rims. OK to use a 26x2.7 Timberwolf on a 17mm (inside) rim but you need a 21mm rim for a MutanoRaptor 29x1.85.

I have used wide tire/narrow rim combos for years without many issues. Just thought WTB's new position was interesting.

 

[JMKM]

Interesting Yes, But not Science.

Interesting yes, but not bulletproof. It is not a definitive test. I spoke with one of their designers at IB. He asked what the interior dims of the new Salsa rim were. It had been so long I had to shuffle through the dimensions in my head to find it. He was more curious than anything and seeing how QBP distributes them I don't think they would want to rip Salsa off. He told me of this new position and I thought nothing of it. Mostly because I feel what they are trying to do is market the rims they design for 29 inch use. I think it makes sense for marketing, but not as a definitive. What they should say is "We think rims with an interior dimension of over x make a 29er tire feel more stable at lower pressures." That is how I fell about it. When you are running 25-30 lbs. in a 2.3 on a narrow rim it feels a little squirmish, I'm sure you could attest to that Shiggy. That is precisely why we designed the new Salsa rim. At low pressures the tire feels stable and solid. That is also why WTB is making some wider rims this year as well.

 

[Bigwheel]

Of course a wider rim is a more stable platform for running lower pressures with a wider casing tire. And thanks QBP and WTB for realizing this and bringing rims to market that will be better overall performers for more people as 29"ers become more popular in the marketplace.

Another aspect that is possibly behind WTB's stance is the use of Stan's? Until there started to be alot of bad feedback from the riding populace about failures with WTB tires and latex use no one really had much to say and life was good. Certainly some of the blame could be placed on the use of narrow rims that put more overall stress on the bead of the tire to begin with. WTB knows it will never be able to stop people from using Stans with their tires but by writing it down that there is no responsibility on their part for failure and trying to point people towards wider rims for 29" use perhaps people will have better luck in the future and less egg will land at WTB.

The people in charge at WTB are not stupid. In fact they are some of the most astute in the industry. The head of WTB, Patrick Siedler, is a lawyer and partner Mark Slate is a MBHOF member that has years of experience in bringing tires/rims to the MTB community. There are skeletons in the closet to be sure, but as problems arise they will try and head them off and keep the ball rolling in the right direction.

 

[shiggy]

Interesting yes, but not bulletproof. It is not a definitive test. I spoke with one of their designers at IB. He asked what the interior dims of the new Salsa rim were. It had been so long I had to shuffle through the dimensions in my head to find it. He was more curious than anything and seeing how QBP distributes them I don't think they would want to rip Salsa off. He told me of this new position and I thought nothing of it. Mostly because I feel what they are trying to do is market the rims they design for 29 inch use. I think it makes sense for marketing, but not as a definitive. What they should say is "We think rims with an interior dimension of over x make a 29er tire feel more stable at lower pressures." That is how I fell about it. When you are running 25-30 lbs. in a 2.3 on a narrow rim it feels a little squirmish, I'm sure you could attest to that Shiggy. That is precisely why we designed the new Salsa rim. At low pressures the tire feels stable and solid. That is also why WTB is making some wider rims this year as well.

I mostly agree with you. It is great that wider 700c rims are becoming available.
A tire can be more stable on a wider rim though it does depend on the tire (tread design) and rim. I have always liked the feel of a wide tire on narrowish rims, especially if the edge tread is tall. A tire with a square profile can have great drive/braking grip. They can also be harder to turn and may not track well. I also find them to feel "edgey" when cornering.
On a narrower rim the same tire has a bit more crown. Tracks straighter for me while turning easier. The rounder profile makes for a smoother transition onto the edge knobs, gives me better feedback and feels more solid to me.
I have run 26x2.6 tires (Fisher BearTrax) on Matix Mt Aero rims (19mm outside) at 18 psi without them being squirmy in the corners. I use the Spec Fast Trak 29x2.00 (casing about the same size as the Exi 2.3) on 22mm (outside) rims @ 32 psi.

This applies mainly to XC/trail riding. No big drops, little jumping. Big tires and wide rims are a better choice for that.

I started using narrow mtb rims in the late '80s. Much of the time I was using 1.5-1.9" tires. Found I would have fewer pinch flats at the same pressure with these tires on a 20-22mm rim vs the more common 28-32mm rims of the time. Dropped a huge amount of weight, too. A rolled down MA-2 is only ~425g vs the 600g of many of the wider rims.

BTW I do want a set of your new rims.

 

[the_eleven]

I am holding off on all rim purchases until the new Salsa arrives.

When can we expect to see them truly available?