Disc Vs Rim Braking System

[Duck!]

Given the points of contact, it is entirely plausible that similar damage would be inflicted with a rim-braked wheel. So you can't blame the disc brake for this either.

A shifter between a rim brake and a wheel? Really?

Spokes & frame. I can't recall whether it was this thread or the other one, but I pointed out that the outer edge of a disc rotor is 70 or 80mm from the centre of the axle, depending on whether it's a 140 or 160mm disc. That's not very far out. Next, the rotor is little more than a single finger thickness clear of the spokes; let's call it around 15mm, maybe a touch more. That's not a huge margin either. So if anything is getting that close in to the wheel and frame in a chaotic manner such as a crash, the presence of a brake rotor does not meaningfully alter the probability of something getting caught between the wheel and the frame, because without a rotor it's highly probable the invading object will end up in the spokes instead. And quite possibly do greater damage in the process. Plus there's the expanse of wheel beyond the edge of the rotor for Stuff to get caught in as well. And less face it, on a non-disc wheel the spokes are actually closer to the frame, and more likely to scissor an intrusion because of the different hub flange offset.

[silentC]

This is so typical of the people in this thread.

What, countering your hyperbole with facts?

[RobertL]

Come up and say hello. Despite what people in here think.. I'm actually a real person, with abilities to look, learn, and logically asses risk. And I didn't make this stuff up! Did you see me looking at the bike and talking to the owner?

Well - there were a couple of people talking to him, and I don't know what you look like. Just that you don't look like your avatar I'll keep my eye out.

[Comedian]

The new Canyon Ultimate Disc. Just like last years model, only 1.4kg heavier...

https://cyclingtips.com/2017/04/canyon- ... i2-review/

[Mububban]

The new Canyon Ultimate Disc. Just like last years model, only 1.4kg heavier...

https://cyclingtips.com/2017/04/canyon- ... i2-review/

I love the discs on my current road bike, and I'm looking seriously at a Canyon Ultimate or Endurace for my next bike, but it'll probably be rim brake for ultimate lightness as I only plan to ride it in good weather.

Give it a few more years and I'm sure they'll keep closing the weight differential between rim and disc

[MichaelB]

The new Canyon Ultimate Disc. Just like last years model, only 1.4kg heavier...

https://cyclingtips.com/2017/04/canyon- ... i2-review/

Really. That's all you got from that article ?

I'd love one, especially in the powder blue !!! Saw one in that colour at TdU and it was noice !!!

[nickdos]

I always thought my next road bike would have disc brakes but I just picked-up my new bike this week and it has rim brakes. I couldn't justify the extra cost and weight for the models I was looking at (or price range I should say). In the end I got the Giant Advanced 2 for $1950. I already had some lighter, more aero wheels, which helped in the decision - Wiggle Cosine 32mm (17mm int width) clinchers. I still think my next road bike will have disc brakes though Technology should be there in 2022.

[eeksll]

I'd like to think I am not a weight weenie, but ...

I'd buy a 1.4kg heavier bike if it where cheaper, but geez, not sure I'd pay more for a 1.4kg heavier bike just for disc brakes.

But then again, I will never be in the market for that level of bike.

[silentC]

Mine is 400 grams heavier than the rim brake version of the same bike. It was quite a bit cheaper too as I recall. I was able to capitalise on the disc-phobia that is gripping the cycling world

[MichaelB]

I always thought my next road bike would have disc brakes but I just picked-up my new bike this week and it has rim brakes. I couldn't justify the extra cost and weight for the models I was looking at (or price range I should say). .....

My highlight.

I find those comments REALLY intersting.

[Comedian]

The new Canyon Ultimate Disc. Just like last years model, only 1.4kg heavier...

https://cyclingtips.com/2017/04/canyon- ... i2-review/

Really. That's all you got from that article ?

I'd love one, especially in the powder blue !!! Saw one in that colour at TdU and it was noice !!!

Yes, there were lots of points in that article. But, I've found with the pro disc-ers that it's pointless really discussing anything, because you just yell and scream and roll your eyes at anyone who dares to question "The Disc". So, I'm just sticking to the numbers as they are more difficult to logically argue. Two years ago, a 8kg $5000+ roadbike would have been laughable.

Some of the points I found interesting. In the last 2 or 3 years I can only remember riding twice in heavy rain, despite covering over 30k in that time. Sure there have been other damp rides, but nothing really wet. I actively try not to ride in the rain, as it makes my bike dirty and it's not pleasant - so I just work around it. So, it seems to me that buying a bike for that one ride a year is an un-necessary complication, weight, and expense. I've said all along that I think they would make sense for people who ride a lot in the rain but that sure isn't me. The weather up here is just too dry and my current setups work just fine.

I’ve spent a lot of time riding road disc brakes and I’ve reached the point where I’ve started to take them for granted. On a day-to-day basis, they don’t do anything to elevate the performance of a bike until it starts raining hard, and then the rider can enjoy little or no change in the quality of braking (though there’s likely to be some squealing from the brakes).

And this.. I really don't think I'd like to be stuck with all that extra weight, all the time...

While the extra weight is equivalent to little more than an extra water bottle on the bike, it can blunt the performance of the bike. This was especially obvious for the Ultimate, because the rim brake version was so impressive for its responsiveness and agility. The Ultimate CF SLX Disc 8.0 Di2 simply lacked the same kick or spark as the rim brake version when it came to tackling a climb or punching over a short, sharp pinch in the road.

As I've said before, if the pro's got an advantage from discs they'd be clamoring for them, but it's a disadvantage..

The rim brake version of the Ultimate CF SLX is simply a better race bike because it is lighter, more agile, and as it turns out, much cheaper to buy.

[silentC]

all that extra weight

Yeah it's a killer dragging an extra 410 grams around. Sorry couldn't find a yelling smiley, those will have to do.

[Patt0]

Getting tired of all the maintenance I am having to do on my disc brakes. 4 sets of pads in 13000km. Don't even get me started on the two minute each change required.

[Comedian]

Mine is 400 grams heavier than the rim brake version of the same bike. It was quite a bit cheaper too as I recall. I was able to capitalise on the disc-phobia that is gripping the cycling world

Care to link with published weights? No other manufacturer that I'm aware of has managed that, like for like.

[silentC]

http://www.merida-bikes.com/en_int/bike ... -6618.html
http://www.merida-bikes.com/en_int/bike ... -6603.html

[Comedian]

http://www.merida-bikes.com/en_int/bike ... -6618.html
http://www.merida-bikes.com/en_int/bike ... -6603.html

Fascinating. Good stuff. I'm curious as to the published weight, as it appears to be for all the sizes. I've only been talking about the lighter bikes to date (where the rim brake versions were 6.5-7) but it's interesting that it hasn't affected the heavier versions nearly so much. I'm unsure why. I did see one review that had the bike at 8.85.

I also find it pretty fascinating that a bike with an RRP of 5200 weighs 8.5kg without pedals. How much did you actually pay for this?

[silentC]

Mine is actually the 2015. It is a 56cm and the weight is about the same as quoted on that site, nearly 9kg with pedals. Those 'endurance' frame bikes are typically a bit heavier. I paid $2,600. At the time they wanted around $3k for the rim brake version.

If you look at the Scultura, there is slightly more difference between the rim and disc brakes. For example the 6000 is 7.89kg rim and 8.41kg in the disc. A bit over half a kg.

[Comedian]

Mine is actually the 2015. It is a 56cm and the weight is about the same as quoted on that site, nearly 9kg with pedals. Those 'endurance' frame bikes are typically a bit heavier. I paid $2,600. At the time they wanted around $3k for the rim brake version.

If you look at the Scultura, there is slightly more difference between the rim and disc brakes. For example the 6000 is 7.89kg rim and 8.41kg in the disc. A bit over half a kg.

Man that's an epic discount.

As I said, I don't understand why the gap is less in the heavier bikes. Clearly though, in the lighter bikes it is much much more significant, usually at least 1kg and sometimes closer to 1.5 kg.

All we ever seem to see from these high end manufacturers is that "The frame is only 40g heavier".. yet their whole bikes are coming in with massive disparities in weights between their older rim brake models. I'd hoped for a logical reasoned discussion to understand the issues but it doesn't look like it's going to happen in here, unfortunately.

I think the only way we're going to know is if and when someone breaks down and weighs all the components. Personally I'm struggling with all this. I'm no bike weight weenie for sure - but I don't understand why people are accepting these massive weight differences but there you go. For me to accept that, I'd have to ride in the rain a lot.

[silentC]

Yes I think they overestimated the demand on the 2015 range. BikerJK has the same bike and he paid less than I did by a couple of hundred I think.

Look, for me 410 grams is not even worth debating. I wasn't particularly after a disc-braked bike when I bought it, my mate in the LBS asked me to consider it. A full Ultegra carbon frame bike for under $3k, it had to be worth considering. The weight difference wasn't even a factor, but I don't race.

Like I said, the Scultura is about 500 grams heavier in the disc, which takes it up over 8kg. What it says to me is that a lot of the weight is in the wheels and the components. You can get the rim version down more with the lighter wheels. Wheel choices are a bit limited with discs, so you are stuck with heavier wheels. The rims that come with that Scultura weigh about 200 grams more in the disc version. So that's nearly half the weight difference right there.

It all comes down to how much the weight matters to you. You're saying the perceived benefits of disc brakes are not worth the weight penalty, I'm saying that for me they are. I like them and if someone offered to swap mine for the rim braked version, I would say no. That's because I don't think that losing the discs is worth the lighter bike

[Comedian]

Yes I think they overestimated the demand on the 2015 range. BikerJK has the same bike and he paid less than I did by a couple of hundred I think.

Look, for me 410 grams is not even worth debating. I wasn't particularly after a disc-braked bike when I bought it, my mate in the LBS asked me to consider it. A full Ultegra carbon frame bike for under $3k, it had to be worth considering. The weight difference wasn't even a factor, but I don't race.

Like I said, the Scultura is about 500 grams heavier in the disc, which takes it up over 8kg. What it says to me is that a lot of the weight is in the wheels and the components. You can get the rim version down more with the lighter wheels. Wheel choices are a bit limited with discs, so you are stuck with heavier wheels. The rims that come with that Scultura weigh about 200 grams more in the disc version. So that's nearly half the weight difference right there.

It all comes down to how much the weight matters to you. You're saying the perceived benefits of disc brakes are not worth the weight penalty, I'm saying that for me they are. I like them and if someone offered to swap mine for the rim braked version, I would say no. That's because I don't think that losing the discs is worth the lighter bike

That's a fair and reasonable argument and I respect that.

[robbo mcs]

As I said, I don't understand why the gap is less in the heavier bikes. Clearly though, in the lighter bikes it is much much more significant, usually at least 1kg and sometimes closer to 1.5 kg.

There is no doubt that the disc brakes put more stress on the frame, forks, rims etc. it is a pure torque thing, as the brake force is applied much closer to the centre of the wheel.

Perhaps the heavier bikes have more solid and stronger components that need less redesigning or strengthening for discs? Whereas the lighter bikes by there nature are less structurally rigid, so need more work?

[Comedian]

As I said, I don't understand why the gap is less in the heavier bikes. Clearly though, in the lighter bikes it is much much more significant, usually at least 1kg and sometimes closer to 1.5 kg.

There is no doubt that the disc brakes put more stress on the frame, forks, rims etc. it is a pure torque thing, as the brake force is applied much closer to the centre of the wheel.

Perhaps the heavier bikes have more solid and stronger components that need less redesigning or strengthening for discs? Whereas the lighter bikes by there nature are less structurally rigid, so need more work?

Yes, I think so but I'd love to know for sure.

https://www.bikerumor.com/2017/01/20/ac ... 150-r9170/

Jumping over to the R9170 components to add in disc brakes, each of the hydraulic Di2 shift/brake levers weighed 158g, adding 45g over the rim brake version. But the new Dura-Ace flat mount disc caliper is just 138g, 22g lighter than the rim brake, not figuring in cable housing/wire or hydraulic oil.

Then you’ll have to factor in the weights for the rotors (not pictured). Weights for new RT900 rotors we’ve seen have been pretty much on par with the previous generation XTR Freeza rotors at 90g for the 140mm version and 14og for the 160mm rotors.

According to this it's only 45 grams heavier for the calliper/shifter units over rim brakes. The rotors are 160 grams for both, so that only a smidge over 200 grams for the different brake hardware for discs.

Pretty much all the manufacturers are offering sweeping statements like "the frameset is only 40 grams heavier in the disc version" or in the case of Canyon 70. That probably excludes the fork, but even if that was 160 grams heavier (which I don't think it would be) then that's only 400 grams. Let's round it up to 500 for giggles.

So, I've still got 500-1000 grams of weight unaccounted for. Which is a lot. I guess it can only come from the wheels, which also seems a lot to me. Early on we were promised that the wheels would be lighter than rim brake wheels but it doesn't look like that is the case at the moment. At ENVE (top end for sure) but they claim no difference.

So I'm still a little bit unsure or where all the weight is going, and I'd still like to see an itemised break down. Maybe one day.

[silentC]

The disc version of the wheels on the Scultura are 100g heavier x 2, so that's 200 grams. So you have about 400 grams for wheels and brake components, which accounts for most of the 500 grams difference between Scultura 6000 and Scultura 6000 Disc.

You would have to do a side by side comparison of bikes that are 1.4kg heavier to see where it all is. According to the article above, the disc is about 1.1kg heavier, unless I'm missing something. But it does seem like a lot.

[Calvin27]

A bro-science breakdown would probably go something like this for me:

1. Wheels up to 500g a set. This is more prominent in higher end bikes because lightweight disc wheels are generally more expensive - it's just a scale thing imo.
2. Rotors x2 = about 90g
3. A little bit of extra hydraulic cable and also hydro hose (+fluid) vs di2 = maybe 20-40g (really guessing this one).
4. Inserts and stuff for the brake caliper and mounts - maybe 100-150g for the whole bike.
5. Caliper.

So points 1 and 3 are especially prominent in higher end bikes (i.e. more likely to have high end wheels and di2).

[silentC]

I dunno. I've done a bit of digging around looking at wheels. I was wrong on the Scultura, I was looking at the weight per set, so it's only 100 grams difference between the rim and disc versions of that wheel. My own wheels are about 50 grams heavier the pair than the same thing in rim brake, and they are nowhere near top of the range. I could definitely get my bike weight down 400g or so by replacing the aluminium rims with carbon, but it would probably cost me more than the bike is worth.

I had a look on the DT Swiss site and their new disc R32 set is actually lighter than the rim-braked version by 15 grams, so go figure...