[WhatsUpcountry]

It seems like a lot of racers run the DT Swiss EX471 rim which has a 25mm internal width - a bit narrower than the normal 30mm that get specced on most trail bikes. I'm just wondering why they go with that rim - whether its narrower profile make it stronger? or more laterally compliant? or is it a tire profile thing?

 

[Cam B]

A lot of them run 25mm but also a lot don’t, and prefer a more traditional 30mm width, keep that in mind.

Narrower rims are inherently stronger, but also the rim been further inboard of the tire sidewall reduces the chance of rim damage.

The narrower rim will round the tire profile more (since they all run WT style tyres still), increasing maximum lean angles in a perfect world, but as we know tyre deformation is greater with narrower rims and does not provide as stable tyre casing.

The fix? WC level tyre pressures and inserts like CC keep the bead and sidewall stiff and locked on.

So you end up with a strong locked on sidewall and casing, greater lean angle potential and less chance of damage

 

[RS VR6]

Some 2.5 tires on a 30mm IW rim can get too squared off.

I don't remember what media publication it was...but for them...they said that a tire can get too squared off and the cornering can get really unpredictable. Loic Bruni and Troy Brosnan both run i25 rims with their Maxxis Wide Trail tires.

 

[2021Mach6]

It seems like a lot of racers run the DT Swiss EX471 rim which has a 25mm internal width - a bit narrower than the normal 30mm that get specced on most trail bikes. I'm just wondering why they go with that rim - whether its narrower profile make it stronger? or more laterally compliant? or is it a tire profile thing?

At higher speed, narrower tires provide less air resistance. Quicker acceleration.

I had to temporarily replace my 2.6" front tire with a 2.4" DHR2 (normal Assegai I run was backordered). Was surprised how instantly noticable the difference was. Less stability, less traction, higher PSI, but lighter and a lot less drag. More nimble and especially coming out of turns, just felt more responsive and had better acceleration. A bit more playful too, like I thought they're more fun to ride.

 

[croakies]

In my experience, The bike is more eager to lean over (nicer for me) and gives more predictable traction at the limit instead of being on/off

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[LMN]

The narrow rim helps a super stiff DH casing tire with an insert flex and find cornering grip.

 

[WhatsUpcountry]

I did hear an interesting tidbit the other day on the downtime podcast with Paul Aston, he talked about a certain rim (I can't recall what brand) that manufactured their rim to be angled outwards to prevent dings and dents since their theory was that most rim impacts occur at an angle (which makes sense because most bent rims bend inward) and if that's the case then a thinner rim would be better protected from impacts of that nature.

 

[croakies]

I did hear an interesting tidbit the other day on the downtime podcast with Paul Aston, he talked about a certain rim (I can't recall what brand) that manufactured their rim to be angled outwards to prevent dings and dents since their theory was that most rim impacts occur at an angle (which makes sense because most bent rims bend inward) and if that's the case then a thinner rim would be better protected from impacts of that nature.

Newmen does it. Off topic but Ive had great luck with mine. Currently running Newmen SL XA 25. 400g aluminum rim. Holding up great on my Enduro bike although I'm a light (157lb) rider w/cushcore.

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[plummet]

Is this 2005? What am I missing? Who the hell wants skinnier rims. ?

They are weaker and flex more and give you worse grip.........

 

[.WestCoastHucker.]

DT Swiss EX471

because it's really light for what it is. dh racers are weight weenie nerds too...

 

[WhatsUpcountry]

Is this 2005? What am I missing? Who the hell wants skinnier rims. ?

They are weaker and flex more and give you worse grip.........

Loic Bruni and a host of other world cup riders, so I'd speculate that it's not supply chain issues making them run the narrower rims.