[Closed] Road discs - A bit of a random musing....

How often are people changing worn out rims? I've got wheels from the 90s still on original rims... my winter trainers go through a front rim every, what, 3 or 4 seasons? 60€ for a DT rr1.1 and a couple of hours to change it. Can't see the advantage of discs for that. They also look gopping (subjective) and I can't comment on this mythical power and 'modulation' as I haven't tried them, but it sounds suspiciously like a bike manufacturer trying to sell me lateral stiffness yet vertical compliance 🙄

However, they would make changing between training & race wheels easier, no pad change required, for the single-biked among us at least.

When I was training a lot, a rim used to last 12-18 months before it'd go BANG (literally...)

But that's irrelevant for me and not a real reason to fit discs unless you have very expensive rims.

The surprise for me was just how much better the control of braking is

This, lots. I don't use discs on my road bike but do on my "knocking about" bike which is a CX bike with road tyres. I miss the brakes every time I ride the road bike.

[i]Hands up those who have actually ridden road bikes with disc brakes and would willingly give them up? [/i]

Never. I've ridden plenty of disked cross bikes on the roads though, loads and loads of them which is pretty much the same thing and I prefer rim brakes on those.

Well there's always one 🙂

How so?

Carbon rims seem to be getting more and more popular but braking performance is not great . Disc brakes solve that one at a stroke .

I did some cycling in the Alps this summer: I kid you not, every single hairpin on Alpe d'Huez had someone repairing a puncture, and as far as I could see, all of them were using carbon rims.

Anyway, the retro-grouch nichemongers grumbling about discs probably also griped about STI shifters and clipless pedals. I'll have Di2 and discs on my next bike, please.

bob_summers - Member

How often are people changing worn out rims?

my 'new' wheels, have now down 3 summers in the peak district, they're noticeably worn.

i'd rather not wait until they fail thanks, i'll give them another 2 seasons i guess? - and that'll mean a £200 rebuild*. that doesn't sound so bad for 5 years use, but i'd rather replace 2x £15 discs.

(*and while i'm doing it, i might as well replace the lovely, but cheap shimano hubs, it just seems such a waste of components that would otherwise last decades)

my 'winter' bike has cable discs (BB5's), they're ace, they don't drag, and they're easier to set up than the calipers on my nice bike.

I'm now in the completely daft situation where my nice bike will be getting cheap wheels as they'll only wear out in a few years, and my 'hack' bike will be getting nicer wheels...

or worse, when my the wheels on my nice bike need replacing, i'll just stop using the bike, and use the winter/hack/commuter all year round.

Are hydraulic discs supposed to give better modulation than calipers?

I'd never noticed.

But then I have Avid Elixirs. 🙁

A lot of people suggesting they are "not needed".

Not really an argument when your riding a flash bike. You don't need all the bells and whistles but its nice to have em.

personally I wont be fussed what brakes my next road bike has, which ever is the best ride and all round package.

How often are people changing worn out rims? I've got wheels from the 90s still on original rims... my winter trainers go through a front rim every, what, 3 or 4 seasons?

Back in the day I used to get about 2 years. That was based on about 6000 miles a year. Normally changed when the sidewall split.

When I was training a lot, a rim used to last 12-18 months before it'd go BANG (literally...)

Hands up those who have actually ridden road bikes with disc brakes and would willingly give them up?

Just mucking around with a new Kinesis Pro6 disk frame and TRP Spyre disk brakes.

Put it this way, I was looking at new mini vees for the old bike last night. I'm not hugely convinced unless I'm doing something fundamentally wrong (possible, but worrying if I am as been fettling bikes for many moons).

Oh, and they can't make bikes 'disk ready' as disk wheels are likely to be 135mm wide, and current road wheels are 130mm....

I have heard that the Spyres aren't all great...

Oh, and they can't make bikes 'disk ready' as disk wheels are likely to be 135mm wide, and current road wheels are 130mm....

That's easy to solve: http://road.cc/content/news/85692-orbeas-new-avant-most-adaptable-bike-ever-seen

My Shimano 105 Calipers work better than Avid BB5 for sure.

I've still yet to understand what road races people ride where they think being able to outbreak someone by 1 second makes a difference.

You'll be wanting us to ride disc breaks on the track next 😉

It's more about being able to stop in time for the lights at the bottom of a 1:5 in the rain with loads of traffic about.

Little things like that 🙂

I'm actually perfectly happy with my current roadie on cantis. But discs are superior in most every ways. Bring them on, I say.

But while we're at it, let's ditch the crapola QR front axle standard and have something a bit more secure, like a bolt through of something like 15mm diameter, oh, and, 135mm rear hubs so that all the MTB stuff is interchangeable. Of course, a heavier stiffer fork is required, but so what. Compensate with a lighter rim.

I can do that fine thanks on pretty much any brake. The biggest problem you'll have is the tyres sliding in those conditions because of cack on the road e.g. branches, oil..., nowt to do with brakes.

The biggest problem you'll have is the tyres sliding in those conditions because of cack on the road e.g. branches, oil..., nowt to do with brakes.

Which is why the superior and more consistent modulation of discs will be a benefit.

I've still yet to understand what road races people ride where they think being able to outbreak someone by 1 second makes a difference.

Who said it was all about racing? 🙂

Oh, and wonhunnerd!

I can do that fine thanks on pretty much any brake

How do you do that then? I've been squeezing the brake lever hard, is that not the correct technique? Maybe it's cos I'm saying 'stopstopstopstopSTOPSTOPSTOOOOOOOP!' to myself.. perhaps if I were more insouciant it'd help.

Compensate with a lighter rim.

I'm not sure there is much room to make a lighter rim easily, as any clincher has to have a depth and lip to hold the tyre on. Plus there needs to be enough metal to maintain structural integrity when hitting pot holes etc.

Plus the addition of a disc and suitable hub will negate the majority of weight savings at the rim.

Something else for discs...

My better half has found (on road bikes with regular callipers) during alpine descents that her grip strength starts running out after a while. She's never said that about any bike that has disc brakes, as the lever force required to stop the bike is just simply less.

Obviously not something to worry about if you have a handshake that scares grown adults.

@ dragon

Plus the addition of a disc and suitable hub will negate the majority of weight savings at the rim.

Fair point.

I'm not sure there is much room to make a lighter rim easily, as any clincher has to have a depth and lip to hold the tyre on. Plus there needs to be enough metal to maintain structural integrity when hitting pot holes etc.

Plus the addition of a disc and suitable hub will negate the majority of weight savings at the rim.

The major pain in the arse with wheels at the moment is the need to have a braking surface. It really limits what engineers can do with the surface - things like golf-ball-style dimples (for aerodynamics), curved/angled surfaces, ultra thin walls etc. Get the brake out the way and you can make the wheel substantially stronger (due to the rim shape), pull out loads of weight (due to getting rid of that big thick braking track) and save on machining costs too.

Let's imagine we have two identical bikes - the only difference is that one has disc brakes (not breaks) and one has rim brakes. Same weight, geo, etc.

Now would anyone actually prefer the one with rim brakes? Given that we know the rim brakes will be less consistent, with less power, with worse modulation and more sensitive to weather etc.

C'mon ....who would rather have the less effective rim brakes?

The major pain in the arse with wheels at the moment is the need to have a braking surface. It really limits what engineers can do with the surface - things like golf-ball-style dimples (for aerodynamics), curved/angled surfaces, ultra thin walls etc. Get the brake out the way and you can make the wheel substantially stronger (due to the rim shape), pull out loads of weight (due to getting rid of that big thick braking track) and save on machining costs too.

I don't actually think that's the case. It seems that the dimensions you need for rim brakes to function are very close to what you need for structural strength. No doubt there's a bit of weight saving to be had but it's not looking like it'll be really significant.

I don't actually think that's the case. It seems that the dimensions you need for rim brakes to function are very close to what you need for structural strength. No doubt there's a bit of weight saving to be had but it's not looking like it'll be really significant.

so they can sell cheaper* rims as a more expensive 'upgrade'.

(*2 less machining operations innit)

i would like Mavic to sell disc-specific open pro rims - all i want is for them to NOT machine the sidewalls.

They would be cheaper to produce, but do you think Mavic would charge a) more, or b) less, for such rims?

I don't actually think that's the case. It seems that the dimensions you need for rim brakes to function are very close to what you need for structural strength

Not according to the people who make ZTR rims.

How much lighter are they than light rim brake rims?

Not according to the people who make ZTR rims.

and if the reference, which i am not aware of, has any connection to MTB rims the minor detail that most modern road rims are deep or semi deep comes into play.

As for the weight thing, take a set of Mavic GEL280s now how many rims are lighter? Consider also they are for rim brakes, then make them lighter.

Havent SRAM already answered all the queries above?

[img] [/img]SRAM Red 22 Hydraulic

Instant compatibility with all existing frames/forks/wheels/hubs
Superb modulation through hydraulics
No weight penalty
No disparity in braking ability compared to cable, meaning no pile-ups in the peloton*

* and UCI-cynic mode = off again

Havent SRAM already answered all the queries above?

They retain the problems inherent to rim brakes. And the levers are seriously ugly!

They retain the problems inherent to rim brakes. And the levers are seriously ugly!

you missed the comment in CW, they're Avid brakes and the tester reported they behaved like Avid brakes... didn't say they were broken just that was refering back to importer as something wasn't quite right/gone floppy/rattley...

Mavic GEL280

They are for tubs are they not?

Better to compare with a clincher, then you are looking at around 400g, might be able to get a bit below that, but this is 700c rim, that has to retain a tyre pressure of say 180psi, so there will be a finite amount of metal you can loose, compare for example a Stans ZTR 29er on weightweenies is 389g, and a Mavic Open Pro 430g, so not much in it.

Then balance that difference by the added weight of disc and hub.

I think the big problem I have in very wet conditions is caused by the amount of water on the rims. Discs should help with that, since the pad pressure is higher, the disc is further from the water and it's got lots of holes in it to clear water.

Double post.

They are for tubs are they not?

true, just trying to make the point that whatever the justification used to go for discs, don't bother with the weight one. The difference in rim weight will never be that great.

My next commuter, tourer- Fargo, Vaya, CDF, LHT et al will be disc because I want to stop quickly at the bottom of a hill in December when I'm still a bit tipsy and its raining etc.

I have no need for em on my road bike because it just needs to go faster that's all that matters, I will have hydraulic assisted legs not brakes on that one please .

I like that honesty/lack of bull about road riding

Erm, you don't subscribe to [url= http://www.velominati.com/the-rules/ ]this[/url] then

I think the big problem I have in very wet conditions is caused by the amount of water on the rims. Discs should help with that, since the pad pressure is higher, the disc is further from the water and it's got lots of holes in it to clear water.

+1

"There's a lot of truth in this - you simply don't brake as often on a road bike, so more power/modulation etc isn't a solution to any relevant problem...

My summer bike's 4 years old, been ridden 50-100 miles most weeks from May-Sept in that time and still has original brake blocks..."

Oh that UK perspective again. In 10 seconds of riding out my door I'm doing 70kph and half the time it's piss wet. I eat pads and get the dissolved pad material all over the shop. Rim brakes are junk and I totally agree with the OP. WTF is going on manufacturers???

That said I don't want them without 10mm bolt thru axles and without electronic gearing crap or on a frame built for old farts with bad backs please.

IanW - you'll go faster overall if you can brake later.

For the poster who reckons saving one second on a corner is nothing - most hills, esp in the alps have more than one corner. That second is now 20, and you've lost the ability to draft.

Rim brakes without brake tracks CAN be built lighter and more aero - marginal gains perhaps, but gains nonetheless, and that's where the road bike industry is at the mo.

Oh, and the rim weight naysayers, ever swapped from a light climbing wheelset at 1000g and an aero at 1800g? If you can't feel the difference on climbs or accelerating away from lights then you must be climbing or accelerating very slow!

JCL - storck had a fully bolt throughed disk road bike at eurobike, although you'll have to accept the (really rather good) electronic gears...

If you can't feel the difference on climbs or accelerating away from lights then you must be climbing or accelerating very slow!

Now there's a man who really needs to learn about the flywheel effect. Things that are really easy to accelerate are really easy to decelerate so heavier wheels go faster for longer...

...and that minus 800 grammes you are accelerating is nothing at all in the total weight of ?100 or so kgs that you are also accelerating at the same time.

Physics; it doesn't change for bicycles.

Flywheel - well yes, that's why tt wheels tend to be deeper and consequentially heavier - tts tend to have less climbing and less sprinting. Why would pro tour riders have both super light climbing wheels for climbing days and deeper aero ones for flat stages and tt stages if the flywheel effect was so beneficial for climbing?

Oh, and I did that exact wheel swap today, there's a difference

Oh, and I did that exact wheel swap today, there's a difference

There's a difference you can feel, for sure.

The actual performance benefit is a tiny and inconsequential one, yet is always implied by to be enormous. That's why the riders who depend on acceleration the most; track sprinters, aren't using the lightest wheels they can.

That's what I said... There is a difference. Never quantified the difference, but FWIW IME it completely changes the feel of the bike. My commute has 50/50 city/dual carriage way. At the lights and up the short sharp hills, light wheels are more sprightly and accelerate better. Heavier aero wheels (both thanks to flywheel and aero effects) give me around an extra couple of kph on the flat dual carriage way sections (if my computer is to be believed) - they hold their speed better, but are more sluggish at the lights and on climbs. I'm off to the alps next week and I sure as he'll won't be taking the aero wheels I'm currently riding on !

Track riders also need to take aerodynamics and stiffness into account though.

JCL - storck had a fully bolt throughed disk road bike at eurobike, although you'll have to accept the (really rather good) electronic gears...

Well that's good to here. They're definitely ahead of the game. There is a lovely 10mm fork by a US company too. can't remember who.

I really don't see the logic behind the complexity and fragility of electronic gearing and the hassle of batteries on such a durable machines as bikes. I appreciate they work well but the benefit to hassle ratio is the opposite of the caliper/disc brakes IMO. They also look horrid too.

Other than charging, they're less hassle ime, as there's no cables to adjust for indexing. Don't even have to charge them that often either.
the new ultegra is a little more svelte, but yeah, aesthetically they're not the best.