RS81 24mm rims - rim thickness question

[AlanW]

It has always been my understanding that the RS81 and the Dura Ace C24 wheel set both shared the same carbon/aluminium rim so the only difference was the actual hub?

I had a pair of the original RS80s and they were indeed a fantastic value for money wheel set, but unfortunately they were not compatible with my recent 11 speed upgrade so they had to go..

So I am now looking to purchase the next generation version, namely the RS81, but concerned about the thickness of the rim if they are still the same as the Dura Ace C24 one?

The description for the Dura Ace wheels states, and I quote: "Low rim weight is achieved by reducing the alloy wall thickness from 1.3mm down to 0.7mm, then a patented phosphoric acid anodizing process is used to bond the carbon fibre to the alloy giving an excellent combination of low weight, strength and rigidity"

But it makes no mention about this reduction in the rim in any description I have read on the RS81 wheels?

Its fair to add that I am quite a high mileage user (circa 15k p/a) and a rim thickness of 0.7mm is pretty useless for me. Although to be fair, these would not be my every day wheels. but never the less Shimano recommend that rims are replaced at wear thickness of 0.5mm so not a great deal of allowance from new!

I usually utilize hand built wheels especially during the winter months because of my high mileage as replacing rims is much cheaper than replacing complete wheels. But at the end of November last year I fitted a pair of RS61 wheels as my every day wheels purely as a trial really, (right price).

However, I have recently (3 weeks ago) had to scrap the rear wheel as the rim had worn down to 0.4mm in 4000 miles. I have since priced it and its simply not cost effective to replace just the rim, so back to the hand built wheels I guess.

I have contacted the likes of Wiggle and even rung around a few of the main stockist and also looked at the Shimano Tech Doc website and nothing?

 

[russ.will]

I'm no expert on wheels, but it seems to me you've reasoned out your solution - RS80s were good for your purposes and the replacement RS-81s aren't, if based on the best information you can glean, endurance is an issue. To be honest, if I can't find out the info I need from retailers/importers/manufacturers, then I walk away.

Mind you (and I certainly don't do the mileage you do) but I seem to wear out rims pretty much equally front/rear. That may just be me being a (portly) ex-biker who has been conditioned into braking with the front and only really using the rear to trim speed, but I have noticed, whilst watching friends crash, that it's the (unloaded) rear that always seems to wash out on them. Do road cyclists fear using the front brake despite this being the loaded wheel with more grip?

Again, not helpful to your question and definitely a segway, but an observation that your experience seems to support?

Russell

 

[AlanW]

I am also a biker of many years experience but have always killed the rear rim first, but to be fair the front rim isn't usually far behind it. As for the RS81 wheels, I agree its time to walk away if I cannot confirm the thickness. Which is a great shame as the previous incarnation wheels as I said before were utterly superb wheels.

I bought my RS80s two days before riding LEJoG, did 900 miles over 8 days over some pretty rough terrain and they never missed a beat, what more do you want?

 

[russ.will]

Thinking about it, most of my mileage is done on the Cambridge-St. Ives (mis)Guided Busway Tow-path, which is very flat and fast, but is very straight with no surprize interuptions. As such, I know exactly what I'm braking for and when and so in almost all conditions, I tend to hit the front brake and leave the rear alone.

It occurred to me, that someone like yourself doing a greater number of road miles, will tend to introduce more rear brake. That is the one that catches road crap thrown up by the front wheel and thus will wear faster.

I recant my earlier assertions, but that doesn't really help your issue. Looking at my Campy Khamsins (Fulcrum Racing 7s) I note that the rim wear depth indicator (on my broadly unbraked rear) barely has a half millimetre of depth to start with. Maybe rims and therefore bottom end wheels in general are increasingly considered as disposable? The competition to become ever lighter (racier) to mirror the pros, is resulting in wheelsets that are both cheaper, but less long lived.

Let us know if you find a suitable current (modern, whatever that means?) alternative, because I suspect you're not alone.

Russell