New MTB rim

[6speedSchwinn]

Hi Folk

 

 

 

My Mavic Crossland rear wheel is due for replacement. I want to build a custom wheel to replace it with and have already decided on the hub (a 32 spoke hub). I am just not sure about the rim.

 

The current rim can still do many more kms, but it is starting to show tiny cracks at the nipples.

 

 

 

I want a tough rim which won't need constant truing (the Crossland has never needed truing in 13500km) and which will give me very high mileage (30000km?). It must also be tubeless. It will be more of an all mountain type rim than cross country.

 

 

 

Which rims will offer me what I am looking for? I am not too concerned about weight, but please don't suggest downhill rims .

[Johan Bornman]

 

It is not the rim that requires the wheel to be constantly trued but the build. Even a rubbish rim should not require constant truing.

 

You can't have your cake and eat it.

 

You are asking for a rim that won't crack and is tubeless. That leaves you with zero options. The two best anti-crack strategies for rims are double eyelets (socketed eyelets) and no anodising.

 

Such rims are not available.

 

If you are prepared to compromise on the tubeless (and why not, conversions are excellent), then your options are better. I'll suggest DRC in this case - either MT 17 or DH 17.

 

 

[splat]

Tubeless conversions can be a P.I.T.A.

 

Mavic 819 rims are UST.

Stans have a whole range of rims which just require some tape.

 

Neither fit into JB's criteria.

 

But whatever rims you do get, spend some extra money and get them built properly. Fancy bits put together badly are useless and a waste of money.

[mongoose_dude]

I have a set of Mavic X819s, the ones that Splat mentioned... They haven't given me any hassles, and I bought them 2nd hand. Would definitely recommend them. I'm heavy (90 kg) and I ride these poor things pretty hard.

 

A very decent rim, and if you keep your tyres pumped at a decent pressure (so that you don't bottom them out) then they keep their true and balancing very well (assuming that they were set up properly).

 

I have also used a set of Mavic CrossTrails, and was VERY impressed. (Quite pricey though)

 

[Overlord]

drc6005. Try them for high mileage.

[Johan Bornman]

DRC have named their road rims ST XX (for Strada) and mountain bike rims MT XX (for montangne). The 6005 refers to the type of aluminium used - 6000-series aluminium. Most rims are made from 6000 series alu since it extrudes nicely.

 

As I've pointed out before, rims, no matter how well made, have nothing to do with the wheel staying true or not. Nor do they have anything to do with wheels going out of balance. Their weight doesn't move around with time. They're born unbalanced and die unbalanced and no-one even notices.

 

 

 

 

[mongoose_dude]

Johan - what about how quickly they go out of balance when they take a knock...? Surely that has something to do with the build quality / strength of the rim??!? 

[Johan Bornman]

Balance is a weight-distribution issue. Even a knock cannot reposition a rim's weight elsewhere.

 

I think you mean out-of-true or run-out. Run-out is where one or more parts of the rim is not running true. A knock can do that but a proper wheel will simply absorb the knock and still run true.

 

When a wheel is built, it is stress-relieved (or supposed to be, but few builders know what it means) where one or more spokes are stressed beyond the metal's yield point and then released. This is pretty violent and a proper wheel suvirves this without going out of true.

 

However, a hard knock can obviously bend the rim and that's fatal, spoke tension cannot fix that.

 

The trend towards lightweight rims and reduced spoke numbers make this more and more likely for smaller and smaller knocks.

 

However, a badly-built wheel made with good quality components can go out of true from a small knock even though the rim will not bend.

 

As rims get older and fatigued, they releax at the spoke holes, reducing spoke tension and causing a wobble. This is normal and a pre-cursor to cracked rims.

 

 

 

[mongoose_dude]

one truly does learn something new every day 

 

I bow down to the master's infinite knowledge!

 

Thanks for the info. Very interesting!