Deep Rim/Short Spokes vs. Shallow Rim/Long Spokes

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mig
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Joined: 19 Oct 2011, 9:39pm

Re: Deep Rim/Short Spokes vs. Shallow Rim/Long Spokes

Postby mig » 24 May 2019, 11:13pm

i'd be at least as concerned about tyre choice. just wouldn't fancy a quick lossy puncture when ripping downhill at 50+mph.

but does that mean new tyres? or something newish with a few hundred miles on them to scrub off the outer surfaces.

FWIW i'd go with shallow rims for the wind cheating effects against a crosswind.

pwa
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Re: Deep Rim/Short Spokes vs. Shallow Rim/Long Spokes

Postby pwa » 25 May 2019, 10:44am

Samuel D wrote:
Brucey wrote:I personally wouldn't favour a low spoke count or especially deep rims. Deep rims can catch a gust of wind worse than shallow rims and this is potentially dangerous; it is windier than normal over many passes and yet it is more important than normal to hold your line accurately on the road too.

And what goes up must come down, so mountain riding also produces high riding speeds at times. The faster you go, the greater is the force exerted by the crosswind.

I found this hard to believe even though it certainly matched my experience of being most affected by crosswinds when descending. But then I found an article by David Norwood called “Car in a Crosswind” that explains it neatly.

I notice the best-informed professional racing teams (e.g. Sky now Ineos) don’t use deep-section rims on mountain stages, even though the bicycles could hit the UCI weight limit with those. I believe the effects of even light crosswinds at 100 km/h, just when you need to steer most precisely, is the main reason.

As a non-racer my main concern going down an Alpine descent has generally been how to slow down without overheating the rims, not how to go faster. So for me the performance factors that matter in the hills are those that count when going uphill, at relatively low speed. I definitely don't want brake rub, I don't want extra mass on the rims and tyres. The ability to cut through the air with ease at 25mph counts for nothing.

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Gattonero
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Re: Deep Rim/Short Spokes vs. Shallow Rim/Long Spokes

Postby Gattonero » 26 May 2019, 10:19am

Valbrona wrote:I want new wheels. I don't want any spoke breakages during long, unladen rides in the high Alps on a lightweight road bike.

A wheel with 32mm deep rims would have shorter spokes than one with 23mm deep rims, obviously. Hubs/spokes/spoke counts are the same.

But do shorter spokes mean less chance of spoke breakages? Or are longer spokes better at 'soaking up' stresses?

Thanks.


First, I'd ask myself why spokes on my wheels are breaking , and where this happens.
It is unlikely a spoke will break in its middle length, it can happen but it comes well after the other two areas: hub side, and nipple side. The former, is often due to stress fatigue and other causes, the latter is most often due to incorrect bracing angle of the spoke and/or drilling on the rim.

Once you got a few answers, start thinking over.

If you're going to the alps, you want a wheel that first of all has a good braking track. Then you want a wheel that is reasonably light, but also solid enough to avoid unwanted flex on the rear (when climbing) and on the front (when going downhill).
In a nutshell, put reliability and safety before weight and very-long-term longevity since you're not having any baggage with you (but bring a wind cape! :wink: )
It is by riding a bicycle that you learn the contours of a country best,
since you have to sweat up the hills and coast down them.
Thus you remember them as they actually are...