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Posted
I I once had a guy after a set of Ksurium SL's of mine for training (he weigh's 100kg) and had already trashed his old ksyrium freewheel hub. I had just had it rebuilt for R1500. Rim only! Spokes are like R60 each and they are very stiff - great for racing but for an enjoyable 3 -4 hours' date=' nah. Don't be pressurised into getting cool/light/fast wheels for training - especially if you don't have a huge budget. Ask your LBS[/quote']

 

I don't understand what you mean by "the spokes are very stiff". I assume these are those unpronounceable wheels with aluminium spokes and steel is stiffer than aluminium. If the wheels have steel spokes, they have steel spokes and the spokes are therefore as stiff as other steel spokes???

 

I'm confused.
Posted
Hey Jeremy' date=' its GregM. I had a Mavic Open pro wheel with Ultegra hub built for my IDT. It was less than R1000 and it rolls really well, is definately strong enough to handle your weight. I am sure the front will be quite a bit less. I recon you could come in under R2k for the set. Got the wheel built at Cycletech near your house.[/quote']

 

What do you mean by "it rolls really well".

 

You may not believe this story but the first wheel invented by a certain Zogg was square and therefore produced four bumps per revolution. A Japanese Neanderthal improved on his design and produced a triangular wheel, the redeeming feature being one less bump per revolution. But your well-rolling wheels? I can't picture them.
Posted

I used Campy Zondas for training & racing for some time, great wheels! The campy wheels wont work with your Shimano gruppo, though.

 

 

 

You can always just fit a shimano freebody to the Campy wheels...

 

 

 

 

 
Posted

OK Johan, help me out please.  Are sealed hubs really sealed or do they add resistance (due to the seal)?  Is it worth getting them or are basic cup and cone bearings still the best?

 

How much should you spend on getting technology on your hubs or is basic best?  So many questions...
Willehond2007-09-06 10:10:06
Posted

The hub spins really freely. Feels like there is very little friction - certainly realtive to Ksyrium SL's I had. Although only used on the IDT, so not sure how they fair on the road.

Posted
Mavic Opens are very strong and good value' date='  or if you want a bit more bling and lighter but more expensive look at the easton circuits. [/quote']

 

I wonder what good value really is. Open Pros cost more than twice what a DRC ST 17 costs and fails more often. I think that is poor value. Mavic is revered as the Rolls Royce of rims and lately, wheels, but in reality their product is pretty mediocre. There are some exceptions and no, it's not a Mavic wheel/rim with an unpronounceable name.

 

Here's a picture of a typical Open Pro failure.

 

20070906_101605_Open_Pro_Crack.JPG

 

Note the cracking around the eyelet (more accurately, socket, or as it is erroneously called, a double eyelet). What happened here is two-fold. 1) The socket failed and the spoke pulled only on the outer eyelet,k forming a small teat in the direction of the spoke pull. With each revolution, the teat relaxes and then pulls to shape again. Normal aluminium can handle a bit of flexing like this, but Mavic chooses to anodise their rims. Anodising is a bit like glass, being a ceramic layer which resides on half on top of the alu and one half inside the aluminium. When the rim flexes, it cracks and like that scab on your knee that hurts when it cracks, the crack propagates into the softer material and the crack propagates right through the material.

 

Here's a similar failure in a DT SWiss R1.1 rim.

 

20070906_102558_DT_SWiss_Crack.JPG

 

The irony here is that his poorly designed rim didn't even need anodising to help it crack it did it by itself, since the rim is painted and paint doesn't propagate cracks. The culprit here is weight saving by way of a single eyelet instead of a socket. Even more ironic is that DT Swiss tried to make up for the lack of sockets by making the rim thicker, that clearly isn't good enough.

 

Here is a photo of a Open Pro and DT swiss rim in cut-through view.

 

20070906_102859_mavic_vs_DTSwis.JPG

 

The DT Swiss rim is on the left, the Mavic on the right. Note how much thicker the DT rim is, even where it is not necessary, namely on the inside where the rim tape lies. I say it is not necessary since, had the rim been made with sockets instead of a single eyelet, the socket could have been supported by the thick inside bed and relieved the stress on the outside area around the eyelet. But, DT decided to save weight on sockets by adding weight to the rim in the wrong places. Makes sense, doesn't it?

 

Here is a photo of another Mavic failure.

 

20070906_103143_Mavic_OP_Extrus.JPG

 

This time the rim failed on the braking surface. It is an extrusion or alloy quality issue since the rim is brand new and had no measurable wear on the braking surface. The owner told me that Mavic  would not replace it under warranty.

 

Let me help with some definitions here.

 

Strong: This means a heavy guy can sit on a bike (wheels) and they can support his/her load without breaking. Clearly all wheels we know are therefore "strong". Id like to think they should also not break when it's payload hits a cat-eye or pothole. That would be my definition of strong.

 

Durable: This means the wheels can support the (intended) weight and do so for an extended distance without failing. I'd like to think this distance should be in the hundreds of thousands of kilometers for spokes and as long as the rim lasts before its braking surface is worn too thin. This could be 500km in rainy, muddy conditions with rim brakes or 50 000 kms in dry Gauteng weather.

 

Stiffness: This is the wheel's ability to transmit torque through its spokes to the ground and, the wheel's ability to not flex sideways when pedaling. In the former, we know from calculations that a rider's weight places more  stress on a wheel than a rider's torque by a factor of 500% or so. Therefore, any wheel that is strong enough (see definition above) is also stiff enough. Regarding lateral stiffness, this is a function of rim stiffness (how much aluminium is in there? ) and spoke count. If your rear rim rubs on your brake when honking up a hill, your wheels are not stiff enough. Campagnolo solved the problem of their not-so-stiff wheels by moving back to single pivot brakes on the rear. Single pivot brakes have a larger gap between the pad and rim. This is a clear indication that reduced-spoke wheels are not stiff enough laterally.

 

If a wheel (or bicycle for that matter) is strong enough, it is strong enough.

 

I hope this clears up some things regarding wheels.

 

JB

 
Posted
OK Johan' date=' help me out please.  Are sealed hubs really sealed or do they add resistance (due to the seal)?  Is it worth getting them or are basic cup and cone bearings still the best?

 

How much should you spend on getting technology on your hubs or is basic best?  So many questions...
[/quote']

 

OK, sealed hubs, here goes:

 

"Sealed" as used in hubs refers to the cartridge bearings in these hubs. Most of us sommer call them ball bearings, but we mean these things:

 

20070906_105233_Ball_bearings_s.jpg

 

The top one is an unsealed or open ball bearing and the lower one a bearing with rubber seals. Cyclists call these sealed bearings. These seals are typically made of rubber, hence the RS for Rubber Seal, denotion on the bearing number.

 

The open bearings are designed for applications where oil can flow freely over them like inside an engine. The sealed cartridge bearings are designed for use in electrical motors and similar applications where the motor sucks air in from the minor dimension (shaft) and expells air at the major dimension (motor windings). That's just how spinning motors work. In order to prevent dust from being sucked into the bearing, they put rubber seals in there.

 

Now, get your head around this: seals that don't leak, leak. If a seal, which seals by rubbing or wiping against the shaft like a windscreen wiper, runs dry, the rubber burns away. In order to prevent that, the seals are designed to weep a little of the liquid it attempts to keep inside and thus lubricate itself.

 

This is evident on hubs and BBs where no matter how carefully you wash the oily residue off from the axles near the hub, the oiliness always returns with its telltale caked dust.

 

In the applications of hubs, a rubber seal is a poor alternative to cup-and-cone bearings as found on Shimano hubs and my older Campag hubs. I don't know about new Campag hubs. The reason being that the rubber quickly deteriorates and water gets into the bearings, ruining them prematurely. Just look at modern BBs and you'll know what I'm talking about.

 

The other thing about a seal such as this used on these bearings, is that a single seal cannot separate two liquids. There must be a draining chamber between the two seals if you want to seal something like car engine oil from a gearbox with its own perculiar oil inside.

 

Why? Because, a seal that doesn't leak, leaks. Because seals do leak, they always contaminate the ouside with a little bit of the stuff they try and protect and if you have two types of oil on either side of the seal, you soon have a mix.

 

In the case of sealed hubs, the alien liquid is water. These hubs work quite well in the dry but in the wet they perform poorly.

 

JB
Johan Bornman2007-09-06 11:03:03
Posted
OK Johan' date=' help me out please.  Are sealed hubs really sealed or do they add resistance (due to the seal)?  Is it worth getting them or are basic cup and cone bearings still the best?

 

How much should you spend on getting technology on your hubs or is basic best?  So many questions...
[/quote']

 

I am guilty of not answering the question properly.

 

1) The little bit of drag the seals produce on the hub is negligible. You only feel it because your lever (fingers) are so short. In the overall scheme of things you should rather worry whether your eyebrows are trimmed.

 

2) Cup and -cone hubs are the best because of several reasons a) They are easily serviced using standard parts, by just about anyone.

 

3) They have two seals, a labyrinth seal and a rubber seal - sometimes several of these as in Shimano MTB hubs.

 

JB
Posted

Firsly my surname is Wheeler - history means I may have been part of the design of the 1st square wheels.

 

 

 

More seriously current profession is to make Carbon wheels for PRO - yes 12 teams in the TDF next years will be using disc wheels and 4 spoked wheels made in Cape Town under licence for PRO.

 

 

 

Unfortunately The best wheels for training for a 98kg (I am 96kg - with 3 x sub 2h30 cycle tours under my belt) person would have to be Spinergy. They have really floppy spokes - you can even knot them, But the PBO fibre is 8 times stronger than steel.

 

 

 

So how can these wheels work if you can knot the spokes - beleive it or not a wheel hangs - so any thing that works well under tension is great for material for building wheels. The added advantage with non ridged spokes is that they absorb a hell of a lot of road vibrations giving a far more comfortable ride, without sacraficing any performance of the wheel.

 

 

 

Now the down side - that out of the budget! Starting at R4900.00 for a new set.

 

 

 

 

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