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Carbon vs. Aluminium Rims.

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Carbon vs. Aluminium Rims.

Old 10-08-11, 03:53 PM
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Carbon vs. Aluminium Rims.

Recently I have been looking into building a set of carbon clincher wheels as a winter project.
The more I look into this the more confusing it becomes. It seems carbon rims & carbon / AL combo rims actually weigh more than plane old AL rims. What am I missing here?
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Old 10-08-11, 03:59 PM
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A clincher rim is U shaped in cross section. The air pressure in the tube is trying to pry the sides of the U apart. That puts both tension and compression on the U. Carbon works well in tension but not in compression.

The second problem is that carbon does not conduct heat well. On a long twisty descent with a lot of braking, the heat generated on the brake track will be conducted through the rest an aluminum rim. With carbon the heat will just build up on the rim walls. Sometimes enough to cause the rim to deform. Or it can cause the tire to come off the rim.
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Old 10-08-11, 04:23 PM
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I don't understand why anyone goes with carbon clincher rims. If your going with carbon, go with tubulars. I'm so happy I did and I'll never look back. I'm going to build a 2nd set of aluminum wheels but they will also be tubulars. Faster flat changes, can ride on them flat, stronger rims, the positives outweight the negatives. Tufo tape is the shiznit and $20 vittoria rally tubulars are great everyday riding tires, those who swear you have to spend $100 on a good tubular tire are full of crap. yes, if you flat, repairing them is a pain but for $20 I'll just throw out the rally's if I flat and if I flat a $100 tubbie I'll send it to www.tirealert.com to have them fix it.

Didn't mean to not answer your original question. Carbon rims are very light IF you go with a low profile. so a 25mm carbon rim can be very light. But most people that go with carbon want their wheels to be aero so they go with 50, 60, or 80+mm depth rims. there is a lot more material to those rims. but if you compare a 40mm carbon rim to a 40mm aluminum rim, ( i think velocity makes one) the carbon rim still wins out in the weight category.
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Old 10-08-11, 04:51 PM
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Originally Posted by ericm979 View Post
A clincher rim is U shaped in cross section. The air pressure in the tube is trying to pry the sides of the U apart. That puts both tension and compression on the U. Carbon works well in tension but not in compression.

The second problem is that carbon does not conduct heat well. On a long twisty descent with a lot of braking, the heat generated on the brake track will be conducted through the rest an aluminum rim. With carbon the heat will just build up on the rim walls. Sometimes enough to cause the rim to deform. Or it can cause the tire to come off the rim.
Great article from November Bicycles on carbon clincher blowups. I ride on November carbon clinchers and love it.

http://www.novemberbicycles.com/blog...r-blowups.html
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Old 10-08-11, 05:49 PM
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have to disagree with dale.

unless you're doing a race, tubulars are just a bad choice.
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Old 10-08-11, 08:04 PM
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I do understand the perceived aero benefit from deep section carbon rims, but I was under the impeason that carbon offered some huge weight advantage. I can't find anything showing carbon is lighter.
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Old 10-08-11, 08:36 PM
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The system weight of tubular wheels is considerably lighter than the same material in clinchers because of the shape of the rim. I can take 400 grams off my wheels by going from clinchers to tubs, same hubs and same campy rims. Check the Ambrosio website, they have cross sections of rims there and you'll be able to see what I mean. When you want to use deep section wheels, carbon can keep the weight down but Al gets heavy in deep sections, real quick.
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Old 10-09-11, 07:10 AM
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Originally Posted by zazenzach View Post
have to disagree with dale.

unless you're doing a race, tubulars are just a bad choice.
I offered multiple reasons, you simply say bad choice with no insight as to why????
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Old 10-09-11, 07:13 AM
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Originally Posted by embankmentlb View Post
I do understand the perceived aero benefit from deep section carbon rims, but I was under the impeason that carbon offered some huge weight advantage. I can't find anything showing carbon is lighter.
Your not understanding, for any given rim depth, carbon rims are lighter. a 25mm carbon rim probably weighs about 300 grams while an aluminum rim would still be over 400 grams. The problem is that a 25mm carbon rim isn't going to be as strong as that aluminum rim. on the flip side, carbon is more versatile for modling into various depths. You simply don't see 50mm aluminum rims because they would be so heavy that they would negate the aero benefits, but with carbon you can make 88mm dept rim that weighs about 550grams, still heavy for a rim but not prohibitive. by comparison, an aluminum velocity deep v weighs 525 grams and that is a very popular alloy aero rim.
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Old 10-09-11, 09:37 AM
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Originally Posted by dalesclyde View Post
I don't understand why anyone goes with carbon clincher rims. If your going with carbon, go with tubulars. I'm so happy I did and I'll never look back. I'm going to build a 2nd set of aluminum wheels but they will also be tubulars. Faster flat changes, can ride on them flat, stronger rims, the positives outweight the negatives. Tufo tape is the shiznit and $20 vittoria rally tubulars are great everyday riding tires, those who swear you have to spend $100 on a good tubular tire are full of crap. yes, if you flat, repairing them is a pain but for $20 I'll just throw out the rally's if I flat and if I flat a $100 tubbie I'll send it to www.tirealert.com to have them fix it.
Carbon clinchers are still a great choice for everyday riders especially when they need to repair a flat on the road. Most of us are not on a team nor we have a team car riding behind us, and we will fix the flat on the spot in middle of nowhere.
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Old 10-09-11, 10:49 AM
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Like 99% percent of questions on BF, the answer to the question is "IT DEPENDS."

I think you need to tell us more about what your goals are, what type of riding you do, how much you weigh, what your budget is, etc. for us to give you good feedback.

And don't get started on the whole tubular vs. clincher debate, that's another can of worms!

I do agree that all things being equal (rim depth etc) carbon is lighter than aluminum. But it's not as strong, so you don't really start seeing carbon rims (or carbon/aluminum hybrid) until you get deeper section (say >35mm).

Anyway, unless the OP give us some hard info on goals and riding style and whether these will be race-day only or "everyday" wheels the masses are just going to spout their drivel.
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Old 10-09-11, 11:24 AM
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Originally Posted by dalesclyde View Post
I don't understand why anyone goes with carbon clincher rims. If your going with carbon, go with tubulars.... Faster flat changes, can ride on them flat, stronger rims, the positives outweight the negatives....
dale, mind explaining this a bit more? I'm trying to decide between carbon clinchers or tubulars for my next bike. From what I've read, a well-glued tubular is a total pain - if not nearly impossible - to seperate from the rim on the side of the road. What is your flat-changing procedure with tubs?
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Old 10-09-11, 02:42 PM
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Originally Posted by datlas View Post
L
I do agree that all things being equal (rim depth etc) carbon is lighter than aluminum.
There are low profile carbon clinchers. Far Sports makes a 20mm one that's 380g. That's the lightest carbon clincher I know of. Compare that with aluminum rims- Stans 340s at 350g, and AC 350s at 360g. So currently with low profile rims, carbon is not lighter than aluminum.

It's in deeper section rims where carbon clinchers are lighter. An aluminum KinLin xr380 is 38mm deep and 550g, while a Reynolds carbon 46mm rim is around 475g.

For comparison, far sport's low profile tubular rim is about 220g, and they make a 50mm tubuiar that's 320g. An Enve 1.45 tubular is 295g. Their low profile tubular is 250g.

Tubular tire (240g) plus glue (10g) weighs roughly the same as a light race clincher (200g) and lightweight tube (55g). Obviously the comparison depends on which models of each that you're comparing. So given that the rims can be so much lighter, there's a distinct weight advantage with carbon tubulars vs clinchers. Whether that's enough to outweigh their disadvantages (takes two days to mount a tire, difficult to change tires) depends on the rider. I've never used tubulars but have ridden with people who have, and it takes them a lot longer to change a tubular than a clincher tube. Perhaps with lots of practice it gets faster. Of course if you carry a spare tubular then the extra 185g over a spare tube eats up a good portion of the weight advantage.

I have a set of carbon clinchers for racing. I do road races in the middle of nowhere with little or no support and want the ease of fixing a flat.
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Old 10-09-11, 03:41 PM
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Originally Posted by jtwilson View Post
dale, mind explaining this a bit more? I'm trying to decide between carbon clinchers or tubulars for my next bike. From what I've read, a well-glued tubular is a total pain - if not nearly impossible - to seperate from the rim on the side of the road. What is your flat-changing procedure with tubs?
+1. Getting a well glued tubular off the rim is a PITA.

It's easier to put a new tube in a clincher, than tear off a tubular. Also, once you've put the new tube in, you don't have to ride conservatively the rest fo the ride like you need to do on the replacement tubular, which hasn't been properly glued to the rim. ( and yes I know you pre glue the spare, but its the not the same as a proper glue job, just enough to limp home.)

Having ridden tubulars and clinchers for 35 years,owning 3 sets of tubular wheels (both al and carbon), a set of Zipp 404 clinchers, and a bunch of aluminum rimmed wheels, for me, I'll take clinchers for everyday riding, and save the tubulars for rqaces or special events.
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Old 10-09-11, 04:52 PM
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Originally Posted by ericm979 View Post
There are low profile carbon clinchers. Far Sports makes a 20mm one that's 380g. That's the lightest carbon clincher I know of. Compare that with aluminum rims- Stans 340s at 350g, and AC 350s at 360g. So currently with low profile rims, carbon is not lighter than aluminum.
That's what I have come to figure out. I guess that my Dura Ace / Open Pros are not to bad after all.
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Old 10-09-11, 05:02 PM
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Like merlinextra light above, there are lots and lots of people who race tubulars and train on clinchers. They have and use tubulars and are fully aware of the advantages, but they are also aware of the disadvantages and don't feel the tradeoff is worth making for training and general riding. HOWEVER, that said, by all means, try them out and decide for yourself.
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Old 10-09-11, 05:35 PM
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Originally Posted by embankmentlb View Post
I guess that my Dura Ace / Open Pros are not to bad after all.
You could lose 80g per rim by going to Stans 340s, and while DA hubs are good quality, they are not the lightest hubs. You could get a set of wheels that are half a pound lighter without using unreliable weight weenie hubs.

Whether that makes a difference is another question. My take is that unless you are racing and your races have a lot of climbing, it's not worth getting all obsessive over. A rough estimate is that losing a pound is worth about 8 seconds per 1000 feet climbed (average 7% grade, body weight 140lbs). For non race riding you can go just a tiny bit harder and gain more than that.
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Old 10-09-11, 06:35 PM
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Originally Posted by jtwilson View Post
dale, mind explaining this a bit more? I'm trying to decide between carbon clinchers or tubulars for my next bike. From what I've read, a well-glued tubular is a total pain - if not nearly impossible - to seperate from the rim on the side of the road. What is your flat-changing procedure with tubs?
Sure, the key is not to use glue. Use the tape. there is debate about tape vs glue but in my opinion in road applications where the tires are at high pressure tape is great. I could see Tape possibly failing in a Cyclocross application with wider tires at low pressure but even if you roll a tire in CX, your probably going at a lot less speed and will land on softer ground. In my opinon, the old school tubular guys are pro glue, us new school guys love tape. I literally pried my tire off in about 15 seconds, put a new piece of tape on, fit the new tire and was good to go under 3 minutes. And you don't have to baby it, that sucker is good to go after a couple of revolutions with your weight on the bike. Now I know experts and hardcore racers can change clinchers pretty quickly but thats probably not most of us.

Riding a flat tubular is also a joy. I got a blowout and was 1.5 miles from the subway, i rode it on the flat without issue (granted, I didn't ride it like a mad man, I was quite careful. IF it was an aluminum tubular, I would have rode as if there tire was still inflated)
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Old 10-09-11, 06:40 PM
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Originally Posted by dalesclyde View Post
I literally pried my tire off in about 15 seconds, put a new piece of tape on, fit the new tire and was good to go under 3 minutes.
You can change a tube in a clincher in well under 3 minutes.

Also, tape is not reccomended by some carbon wheel manufacturers.
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Old 10-09-11, 06:42 PM
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Originally Posted by zazenzach View Post
have to disagree with dale.

unless you're doing a race, tubulars are just a bad choice.
Why? I ride both AL and CF tubular rims and I don't race. They are far superior to clinchers in my opinion. Less flats, they ride better and the weight reduction is noticeable and wonderful. They are easy to replace (I use the Tufo tape and tires - which I like better than any clinchers I've used) on the rare occasions when I do have a flat. I would never go back to clinchers.

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Old 10-09-11, 06:45 PM
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FWIW, I have a set of 44mm tubulars from Yishun bike that cost me $450 shipped to my door, arrived in less than a week from China (still don't know how I got them so quickly) and they weigh in at 1338 grams with Chosen hubs and CN Aerospokes. Lightweight, Aero, and under $500 and I'm a full fledged clyde at 240lbs, no problems with them thus far.
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Old 10-09-11, 07:24 PM
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For the longest time I resisted tubulars as everyone was saying what a pain in the ass they were, etc. I finally bought some, and so far so good. The initial set up takes a couple of hours over a few days, but other than that, I do not find them to be a hassle at all. Pre-glued spare in the jersey, and once you get the technique down, changing out a flat is straight forward. (True, you have to take it easy on the ride home.)
The improvement in ride quality was certainly worth it, and the bike is almost a pound lighter. (I replaced DA 7850 clinchers w/Vittoria open corsa tires)
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Old 10-09-11, 08:01 PM
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Originally Posted by merlinextraligh View Post
You can change a tube in a clincher in well under 3 minutes.

Also, tape is not reccomended by some carbon wheel manufacturers.
out of 100 cyclists, how many do you think can change a flat in a clincher in well under 3 minutes? I put it at 20% max. I honestly think a tubular user that uses Tufo Tape would raise that percentage over 50% with the added time mainly being taking a few extra seconds to triple check that the tire is mounted evenly (which is really not as hard as people make it out to be)

As for tape not being recommended by carbon manf. Show me. If anything it has to do with the cyclocross issue i mentioned earlier. there are also tire manf who lie and say you can't use tape because they want you to buy THEIR brand of glue. (or in the case of tufo, they tell you their tape is specially made for their tires and not to use other brands of tape, heh yeah right)

There is only 1 think I don't like about tubulars; being a clyde there aren't a lot of options in 25mm width which would help me out quite a bit. lots of 19 and 21mm tires though which would be great if I was 135lbs!

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Old 10-10-11, 06:17 AM
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It's the same 100 cyclists that could change a tubular in probably less than 3 minutes. I'm pretty good with both, and I find changing a tubular to be easier and faster.

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Old 05-16-12, 10:20 PM
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Originally Posted by dalesclyde View Post
FWIW, I have a set of 44mm tubulars from Yishun bike that cost me $450 shipped to my door, arrived in less than a week from China (still don't know how I got them so quickly) and they weigh in at 1338 grams with Chosen hubs and CN Aerospokes. Lightweight, Aero, and under $500 and I'm a full fledged clyde at 240lbs, no problems with them thus far.
where are you from? shipping less than one week very normal
 

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