PT Rim Lacing

FeltF45 said:

Ok, well I broke down and bought a Powertap SL. I orderd it straight from CycleOps through my local bike shop. It is built by Quality Wheel House on a 32 hole Mavic Open Pro rim. When it came it I was looking at the lacing pattern. My problem is that its 2x on both the drive side and non. Im 5'9 and weigh around 135 pds.

When I bought this weel, I wanted the sturdiest, heavy duty wheel I could get to go with the hub for 2 reasons:

1. I dont want ANY flex in the rear wheel for the most accurate reading I can get on the PT.
2. I put on around 20,000 miles a year (I work 1 day a week) and I want it to last as long as possible.

So, do you guys think that is a strong enough wheel for the purpose that Im using it for? Or do you think I should just shell out a little extra money and have it relaced with 3x?

I just had a PowerTap SL, 32 hole laced 3x to a CXP33 rim and I think it'll be plenty strong for my 240lbs. I'd guess that 2x wouldn't bat an eyelash at 135lbs...

FeltF45 said:

My problem is that its 2x on both the drive side and non. Im 5'9 and weigh around 135 pds.

If it came straight from Graber, how did the wheel get built by this other place? It either comes as the hub or a built wheel. If it's a built wheel, the three I have bought come with 3x. Are you sure you they are 2x? But maybe they changed things. If the retailer built the wheel, why did you not specify how you wanted it built? Do you a history of problems of destroying wheels? If not, I would not worry about it.

Woofer said:

If it came straight from Graber, how did the wheel get built by this other place? It either comes as the hub or a built wheel. If it's a built wheel, the three I have bought come with 3x. Are you sure you they are 2x?

Funny thing - in the old instruction book they used to recommend 3x due to the unique torque, yada..yada..yada... Well, the new booklet says at 'least 2x.' I guess now that there are more of them on the road they've had a better chance to see how well the wheels really hold up.

Woofer said:

Are you sure you they are 2x? But maybe they changed things.

Given the size of the PT's hub flange the first cross in a 3x wheel is very close to the hub and easily missed when counting.

FWIW, I don't see that 2x or 3x makes much of a difference in this application. Any minor strength difference should be balanced against the larger hub flange and shorter spokes.

FeltF45 said:

Ok, well I broke down and bought a Powertap SL. I orderd it straight from CycleOps through my local bike shop. It is built by Quality Wheel House on a 32 hole Mavic Open Pro rim. When it came it I was looking at the lacing pattern. My problem is that its 2x on both the drive side and non. Im 5'9 and weigh around 135 pds.

When I bought this weel, I wanted the sturdiest, heavy duty wheel I could get to go with the hub for 2 reasons:

1. I dont want ANY flex in the rear wheel for the most accurate reading I can get on the PT.
2. I put on around 20,000 miles a year (I work 1 day a week) and I want it to last as long as possible.

So, do you guys think that is a strong enough wheel for the purpose that Im using it for? Or do you think I should just shell out a little extra money and have it relaced with 3x?

1. Flex in the rear wheel will have no effect on the accuracy of the readings, as power is being measured "upstream" of the hub/spoke, spoke/spoke, and/or spoke/rim interfaces.

2. Normally you'd build a 32 spoke wheel 3x to optimize the pulling angle of the spokes at the flange, but the PowerTap hub is larger in diameter than is usually the case, such that excessive crossing of the spokes over the flange may occur. This is probably why they built it 2x...but even that is acceptable on a standard diameter hub, so I see no reason why it would create durability problems in this case.

In any case, whether the wheel is 2x or 3x won't significantly affect the lateral stiffness of the wheel, which is primarily a function of the flange width (spacing) and especially the spoke tension. The amount of "wind-up" that occurs might be greater for a 2x vs. a 3x wheel (depending on the actual angle of the spoke relative to the flange in each case), but this is 1) tiny in any case, and 2) is lessened further when using a PowerTap hub since the larger central hub diameter means that more of the torque is born by the right-side flange than usual, meaning that there are more spokes sharing this load.

BTW, for two years the only wheel that I used for both training and racing (~450 h/y) was an 24 hole PowerTap laced 2x to a Velocity Deep V rim. The latter rim is stiffer/stronger than what you're using, but you've got 8 more spokes and weigh 15 lbs less than I do - I therefore think you won't have any problems (assuming that the original build was done well).

Okay, I'll bite...

What do you do for a living that allows you to get by working 1 day/week and still afford nice toys like a PT SL?

I "help out" at the LBS. Also momther and father help out a little bit. Things are good when your 19 years old....

Ah... I miss those days (not that it's been that long...). Live it up!

re:anecdotal evidence - my main race wheel is a PowerTap 32x 3cross 14/15 db, ordinary hub with a Velocity Deep rim, and almost all my other miles are on a PowerTap ordinary hub 32x 3 cross 14/15 CXP33, weigh 150-155 and don't have any issues, ride off road on my road bike quite a bit. YMMV.