Mavic D521

[Anthony]

I've just built a new front wheel for my ti KHS. It's a very fast bike and the frame and forks are seriously light at 3.1lbs plus 2.8 = 5.9. It flies along level trails, and uphill, and descends almost like a full-suspension bike. The only problem is that it has a slightly vague steering feel compared to any of my Konas. Clearly the 3.1lb frame is light even by ti standards - e.g., a Hei Hei of the same size weighs c3.5, and 13% heavier means 13% stiffer. Combine that minimal frame with an SID, and maybe it's actually *too* light. Yes, there is such a thing friends.

So I built up this Mavic D521 on a Hope XC (?), in the hope that it would add a little stiffness.

It's quite a well-worn rim, but it still weighs 550g. It's a good job I'm not a weight weenie, as adding 145g to a 517 weight would seem like a bad idea to some, but it feels way stiffer than a 517 and also the 21mm internal diameter is helpfully greater than the 517's 17mm. It certainly feels to me as if the bike now steers better than before and it makes it a faster bike, even though it has added weight.

I wonder if anybody else has tried using a D521 for pure cross country and formed a similar impression, or is it just my imagination?

 

[tommorth]

less movement of the tire on the rim maybe helping
nice bike too

 

[MikeD]

I'm a bit sceptical that it's wheel stiffness due to the rim making the difference. Wheel stiffness is mostly down to spoke tension -- are the two wheels equally tight? The shape of the front tyre will also be significantly different on the wider rim -- biggish tyres on narrow rims sometimes get a bit "pointy" and weird.

 

[mechagouki]

I started a similar thread a while back - got a few responses:

http://www.retrobike.co.uk/forum/viewtopic.php?t=149904&highlight=d521

I see you're running Arch Rivals - did you have any problems with the wide rim? I have my 521s on a TREK singletrack now - the bike was built for canti's and I'm not happy with the angle of the brake arms I'm using (Single Digits) in relation to the rim - even with the narrower spacers inboard.

 

[Anthony]

Thanks Charlie, I should clearly have done a search. You did get quite a few replies, but still most of them saying that the D521 was a great rim, which is not in question, but few expressing a view as to whether they found it faster for xc than an X517. I think the width does certainly allow the tyre to do a better job, especially with the fatter size tyres we have now, but I do think it also makes a stiffer wheel. I don't agree that it is only spoke tension that governs the stiffness of a wheel.

On your other point, I'm happy with the set up of the Arch Rivals. For a 517, I use the bigger spacer plus a washer, but here I have used the smaller spacer and the brake arms sit pretty much vertical on an SID, which is how I like them. I have a retro magazine article that says you should set up V-brakes with the arms splayed outwards, as that gives more power. I should have thought not - surely the closer to vertical, the straighter the path of the pads to the rim and the better the grip when they get there?

 

[jimo746]

I have the D521 rims on one of my bikes, which previously had 230TIB's and then 217's on it. Although the 521 is slightly heavier and wider I'm happy to live with that as it's far easier to get tyres on/off the rim, and in all honesty the extra few grams is not noticable once moving on the trail.
I agree with the wider rim altering the tyre profile though, but for me that's a matter of personal preference, I can soon adjust to that.
I believe the 521 is a stronger rim, but as for stiffness I'm not so sure, I think it's the whole package together that gives a different feel. I do know however that my 521 wheels have quite modern LX hubs which are designed with suspension forks in mind, compare this to the 217's with weedy DX hubs and you can feel the difference, the 217's feel "springy" and the 521's feel stiffer.
If you're happy with your new wheels then that's what matters, and the extra few grammes only matter if you prefer to weigh your bike rather than ride it