# Ok, what's with discs?



## Xiorell (25 Apr 2011)

So are they even worth if unless you're really into downhill and such?



Some of you may know I am gonna embark on a project to build a bike out of bits I've gathered up. Knowing full well this approach isn't going to make an awesome bike (due to me doing it on the cheap as a "learn bike mechanics" thing), I wanna make a full suspension mountain bike affair.

This is due to the fact my hybrid is totally rigid so I might has well go polar opposite with this, plus there are a few off road places I intend to ride where my rigid frame rattles the hell out of me.


I'be been looking at frame and fork that can mount discs. But really, if I stick to V-Breaks do you think I'd be missing out?

Yes the off road places are pretty rough (more so than I remembered) and yes, it would be out in the wet and muck come autum/winter.



Just seems if I ditch the disc break thing I got more options but I get the feeling they'd be better when things get rough.



Opinions please!


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## Angelfishsolo (25 Apr 2011)

Top end v brakes are as good as entry level disk brakes. Once the disk quality increases there is no comparison. Cable disk brakes are a good middle ground and far easier to service than Hydraulic ones.

Best of luck on the project


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## Angelfishsolo (25 Apr 2011)

Top end v brakes are as good as entry level disk brakes. Once the disk quality increases there is no comparison. Cable disk brakes are a good middle ground and far easier to service than Hydraulic ones.

Best of luck on the project


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## zizou (25 Apr 2011)

In the dry then good v brakes with good quality pads can provide really good stopping power - but out in the wet and muck then there is no comparision, probably the single biggest improvement in mountain bike technology in the last 20 years or so.


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## ColinJ (25 Apr 2011)

It's not just the braking - it's also a big relief not wearing rims and brake blocks out at an alarming rate on wet, gritty rides!


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## Bicycle (25 Apr 2011)

I was a long-time anti-disc luddite.

I still have an old Trek with V-brakes and they're really rather good.

But... against my better judgement I bought a lightweight hardtail (Pace) with discs... and...

They have been quite superb.

I am now a complete convert to hydraulic discs on MTBs.

I'm still a luddite about carbon, full suss and lots of other recent-ish technologies, but hydraulic discs on an MTB are really worth the extra weight.

No fade, very low pressures needed on the levers, no worries about doing a rim, few worries about performance in the wet or in shallow water.

I was quite surprised how good they were and how good they remain.


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## david1701 (25 Apr 2011)

if you can get disk forks go for it, I have front disks and I've never yet been in a position where I couldn't just stop if I wanted to


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## 3narf (26 Apr 2011)

I've just fitted a set of Avid Juicys (I got them cheap or I probably wouldn't have bothered).

They are great; predictable, consistant and almost maintenance-free.

I was never convinced by the science - all that braking force going through a 2" dia hub flange - but they seem to do the job!


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## Xiorell (26 Apr 2011)

Ya see I have used disc breaks before but this was years ago in school. My girlfriend lived way over town so I used here bike for about 3years. I'm sure that was discs both front and back but it was that long ago I can't remember what they was like lol.



I'm watching a bike on fleabay at the moment, that's all discs so if it doesn't go to high I've get that as a basis to build better stuff onto.


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## Globalti (26 Apr 2011)

It's BRAKES.

Breaks are what you get between lessons.


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## Xiorell (26 Apr 2011)

Globalti said:


> It's BRAKES.
> 
> Breaks are what you get between lessons.




lol, didn't realise I was doing that


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## jethro10 (26 Apr 2011)

Not wearing out rims with wet gritty mud is a big plus for disks, as mentioned above.

Also mentioned, on long down hills, only needing gentle pressure with hydraulic brakes is a boon for tired hands compared to cable disks or V's

Jeff


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## Zoiders (27 Apr 2011)

It does really depend on how hard you push your riding to be honest.

On more vanilla stuff discs and good quality V's have very little to separate them, the only advantage over V's being the rim wear and set up issues like the others have said.

If you are in to slightly more epic and brutal stuff on trails, stuff like fast switch backs, long fire trails, short but very steep descents and the like then discs are full of win as they let you check your speed without locking the wheels or going over the handle bars, V's tend to give you all or nothing on the really hairy stuff or the pads just vanish in rapid order.

You need to get out there and ride the really technical and fast trails to see the true worth of discs off road.


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## MontyVeda (27 Apr 2011)

slightly off topic but I've never been convinced by V brakes... I'm still on the original calliper brakes which came with the bike. I find V brakes lock the wheel too suddenly, which isn't very effective braking as the most efficient point of braking is just before the wheel locks. Plus, I know two people who've had broken collar bones from accidentally (or ignorantly) hitting the front brake on a fast descent... in a way they're too efficient.


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## Muddy Ground (27 Apr 2011)

Personally I've always hated v-brakes - they were promised as being all-powerful but I never found them to have any real ooompf. Just incremental over calipers, which were themselves awful, especially in the wet. Disc brakes are just lovely, especially hydraulic ones. OK the pads can wear in a single gritty ride, and fork judder can be annoying, but the stopping power is always there, dry or wet. As mentioned you want a brake that takes you right to the edge of the tyres adhesion on any given surface; discs give you that ultimate control.

And I did give v-brakes a fair chance; even going right up to XTR. I stopped short of ceramic rims though. None of them were any bloomin' good.

www.muddyground.com


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## subaqua (28 Apr 2011)

I have hydraulic disc brakes on my MTB. I use it as a commuter and they have saved my skin a few times when I have needed the extra stopping power, usually when a ped on a mobile steps out without looking 2 ft in front of you. the backward step into the ropad is a classic manouvere.


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## Xiorell (30 Apr 2011)

OK I'm sold.

Went over some rough downhill terrain today and the V-Brakes just fizzled out around 20mph or so, just couldn't stop me in a hurry.


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## Andy_R (30 Apr 2011)

I was a bit of a brake luddite too, until I tried them. To stop a fat lad on a bike going down that 'orrible little hill inbetween Garrigill and Nenthead takes some serious doing. Mass x Momentum = Stopped by Shimano XTR


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## Muddy Ground (30 Apr 2011)

_Went over some rough downhill terrain today and the V-Brakes just fizzled out around 20mph or so, just couldn't stop me in a hurry.

_V-brakes have always been a bit pants on mountain bikes. I can remember many a situation as you describe - and this back in the day when everybody was going on about how good they were! Utter tosh. The only contenders are Magura hydraulic rim brakes; they are good.

If you can, spend a bit more and get some hydraulics. Apart from wearing out pads, they are generally fit and forget items. Just don't believe the hype that you need massive discs to get the job done; 160mm rear, 180mm front is enough for the UK.

Good luck!

www.muddyground.blogspot.com


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## yashicamat (30 Apr 2011)

Although there is a power advantage of disc brakes over rim brakes, I find the single biggest benefit is the modulation. I can feather the brakes right on the limit of traction on very very steep ground far more easily with discs than I ever could with rim brakes, yet still have bags of power in reserve if I let go for a few seconds and get some speed up.


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## Zoiders (30 Apr 2011)

You need to watch you disc size with forks that have a standard quick release, you can torque the wheel right out of the fork under braking.


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## tradesecrets (4 May 2011)

Main issue that nobody has mentioned thus ... 

What kind of brake is actually more cost effective long term ....and actually offers better value for money 

Cantilever brakes are easier to fit and less messing about 

disc brakes .. -- may work a treat but replacing the disc and brake pads will cost more than buying pads for Cantilevers fact plus the mineral oil ..


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## Globalti (4 May 2011)

tradesecrets said:


> Main issue that nobody has mentioned thus ...
> 
> What kind of brake is actually more cost effective long term ....and actually offers better value for money
> 
> ...



I disagree. Using cantis then Vs I was changing my rims every year, I got to be pretty good at taping the new rim alongside the old then transferring the spokes over and re-trueing. At that time a new rim was £50. I'm now running the same rims on early Hope hubs that I bought second hand when I went over to Hope Mini discs about 8 - 10 years ago.

Setting up discs is pretty easy; the hardest bit is aligning the caliper with the disc and getting the disc running straight. Once this has been done they are fit and forget. I use a Reba fork and a rigid carbon fork on my MTB and amazingly the same combination of spacer washers even works on both forks, so changing the fork is a doddle. Cutting hydraulic pipes and bleeding are easy as well if you read up on it first. Once you've set them up you only need to change the pads and give everything a bit of a clean up once a year. Compare this with the ballache of setting V brakes up, contacting the rim right, toed in to prevent squeal, then realigning half way through their life... a constant pain in the jacksie especially when riding competitively in wet gritty terrain and wearing out a set in one day. Admittedly there's a roughly 100gms per wheel weight penalty with discs but it's worth it.

For XC riding 160mm discs are all you need, as Zoiders warns, the tension with a 180mm disc can pull your QR right out of the dropouts in extreme braking.

I use a standard pad for my front brake and sintered for the rear, which operates in wetter muddier conditions. The standard pads brake a little better than the sintered, which are also quite noisy.

After around 8 years the discs are barely worn, pads are designed softer so they wear in preference to the discs.

Contaminated pads can be cleaned by popping them in the dishwasher.


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## Zoiders (4 May 2011)

tradesecrets said:


> Main issue that nobody has mentioned thus ...
> 
> What kind of brake is actually more cost effective long term ....and actually offers better value for money
> 
> ...


Service intervals.

For actual real off road use the service intervals with a disc brake are far less, try exposing a V or Canti to the same use and you will be eating through pads on a regular basis and having to go back through the toe in set up again and again. Cables - hydraulics are a closed system and not vulnerable to dirt and water ingress like wire brake cables are.


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## hotmetal (4 May 2011)

On my mountainbikes I've had all sorts over the years: 

On the front of my old Saracen there were normal cantis, which had little power or modulation. The back had a 'u-brake' which was as rubbish as normal cantis, but also located under the chainstays where all the mud seemed to end up.

My Cannondale ST had cantis on the front and an odd Suntour Rollercam system which was kind of better than v-brakes, and predated them too, but never caught on because the braze-ons had to be in a non-standard position. This was actually a pretty good brake – too good for the back wheel in those days, except for the fact that it would also clog with mud if you went riding in sticky clay (but that's true of any bike to a greater or lesser extent, yet strangely doesn't affect my front wheel on the Lefty fork!). 


My Rocky Mountain Element had Vs at both ends - they offered better braking than cantis but were useless in mud or wet, which is a major flaw for anyone mountainbiking in the UK. Not to mention the rim and block wear! Even in the dry though they were not powerful enough: I remember chasing a couple of lads on full sussers with discs across the alps. I got to the top first every time but simply couldn't hold the speeds coming down because I lacked the stopping power, and my forearms and fingers hurt more than my legs by the time I got down. In summary, Vs are ok for light duty but not the best for serious sport, and as someone posted earlier, they can be too abrupt for beginners - some 'granny' bikes came with Vs, but they had a cam system fitted to make locking up the front wheel more difficult. 

I also had a Canyon (German brand) which had the legendary Magura HS33 hydraulic rim brakes that MG mentioned above. These really are the dogs danglies of rim brakes, but sadly the usual caveat of grit and mud and rim/block wear applies. Fantastic brakes though – made me reappraise what rim brakes were capable of. 

The Cannondale Jekyll has got Magura Marta hydraulic discs. Again, only 160mm rotors, believe me that's enough for most trails in the UK on an XC/All Mtn bike - only DHers with heavy bikes on serious trail centre courses really need more. The modulation is spot on, if you want to launch yourself over the bars you would have the power available, but they offer so much feel you just wouldn't - even in a panic. Servicing-wise it's not a huge consideration - yes, good disc brake systems aren't cheap to buy but running costs I would say are comparable - a disc lasts for years unless you bend it, a set of pads lasts longer than a set of v-brake blocks, costs about £15 and doesn't need fettling. No cables to replace, etc etc so are easy to maintain. Plus your rims don't get ground away every time you use them in bad weather. 

I did have a problem of mine going spongy once, but got a competent LBS mechanic (who I happen to ride with!) to bleed them and they're like new. Only cost £15 for the bleed. I did once bend a disc in an accident, Magura discs are a bit dearer than Shimano ones (£35 IIRC) but even this was cheaper than the rim wear I used to suffer. Discs therefore are well worth the money if you're serious about off-road, but are a bit overkill for road.

Below is a pic of the Rollercam brake - a bit of nostalgia! This bike also had a 24" back wheel and 26" front as standard. It's a 1988 Cannondale - fully rigid in those days.


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## Muddy Ground (4 May 2011)

Surely the size of the rotor used is not dependent upon the use of a quick release or otherwise; my Magura forks are rated to 210mm and are quickies. Check the rating of the fork?

Hydraulic discs every time on a mountain bike these days. Anything else is just second best. V-brakes I can remember toeing in at the start of a ride, again half way through, then still being annoyed over their lack of power and squealing noise when used.

www.muddyground.blogspot.com


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## Globalti (5 May 2011)

I once wrecked a rim in about ten seconds when riding through slushy snow; the brake block picked up a piece of stone, the brakes and rims were clogged with ice and I held the rear brake on hard to try to warm it up and dry it out. There was a terrible grinding noise then a few seconds later there was a bang and most of the rim peeled outwards like a long spring allowing the tube to explode. On examination I found that the stone had machined its way through the braking surface leaving a deep groove, along which the rim split open. Another fifty quid down the drain.


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## ColinJ (5 May 2011)

Globalti said:


> I once wrecked a rim in about ten seconds when riding through slushy snow; the brake block picked up a piece of stone, the brakes and rims were clogged with ice and I held the rear brake on hard to try to warm it up and dry it out. There was a terrible grinding noise then a few seconds later there was a bang and most of the rim peeled outwards like a long spring allowing the tube to explode. On examination I found that the stone had machined its way through the braking surface leaving a deep groove, along which the rim split open. Another fifty quid down the drain.


Ouch!

I destroyed a rim when I overestimated how long my brake blocks would last on a wet, gritty winter ride. One pair of blocks wore out on a fast descent. I had no option but to continue braking despite the horrendous noises coming from the rim as the brake shoes wore through it. The rim didn't explode but it was worn out and cracking when I looked at it at the bottom of the hill. I lowered the tyre pressure and managed to limp home but after that the wheel was no longer safe to ride. 

Compare the price of a pair of v-brake blocks to a new rim and wheel rebuild; it was an expensive mistake to make!


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