Disc brakes for a 700c tourer?

[Bren]

It's an Enigma fork (on an Enigma bike appropriately enough).
It has mudguard and rack fittings.

[insanityideas]

I have 160mm discs front and rear on my MTB, the only time I have ever experienced brake fade was decending a 3 mile 20% hill, it was too twisty to let the bike go quickly so I was constantly on the brakes. I completely cooked the rear brake as I was using it for speed control. When I felt it fading I used the front to stop the bike at a gateway and waited a couple of minutes for it to cool off. I had made the disc go a funny colour and the caliper was too hot to touch and the frame around it was quite warm. Once it cooled off it worked just like before.

Going down that hill on subsequent occasions I have used the brakes properly, braking harder and then coming right off the brakes, and also alternating use of front and rear. Never had any problems with overheating since. On one occasion I deliberately tried to overheat the brakes to see how bad the fade would get, it just made a bad smell and squeaked for a while afterwards, no complete failure or loss of power once the brakes had cooled.

Just so people are aware of the forces involved I ran the numbers on PowerCalc, keeping to 20mph on a 20% hill requires you to loose a constant 1300watts of power through the braking system. Without brakes you would be doing a terminal velocity of just over 40mph.

On lesser slopes I have known people have tyre blowouts, at least brake fade is a predictable and gradual failure mode with plenty of warning.

I have never had a problem with pads glazing or warped rotors. I think quite often people confuse glazed pads with ones that have been contaminated with oil (even off your fingers touching the discs). Pads should look reasonably shiny when properly bedded in, this doesn't mean they are glazed. With new pads you do need to do a bit of aggressive braking to wear them in, but only a few stops not a crazy amount. Should pads be contaminated you can easily resolve this by either heating them on a stove till they smoke a bit or use a solvent on them followed by a bit of sandpaper. Rubbing a bit of degreaser on the discs or letting them get wet helps if you think they are all oily.

Compared with rim brakes discs are so much less fuss, they need adjusting rarely, take much longer to wear out and work properly in virtually any conditions. If you do damage the disc it takes about 20 minutes and £20 to replace.

[andrew_s]

A 203mm disc
Have you got quick release hubs?
If so this could be a problem......the braking force acheived with hydraulics has been known to rip a QR wheel from the fork !!!!
MTB tend to run smaller disc unless running on a 'maxel' ( a 20mm axel that secures/theads into the fork and can withstand the extream forces involved).
I have 210 on my On-One, bot it has the bolt through.

Disc brakes pulling a QR wheel out of the dropouts is a problem, but the problem will be worse with smaller discs than it will with bigger ones.
If you use discs, make sure to keep the lawyer lips and check the QR regularly, or put the disc on the front of the right-hand fork blade instead.

[Bren]

Here are the pictures of my fork:-





In the background is my GF's new bike- a Marin Toscana. It also has discs and 700cc wheels plus all the fittings for guards etc. When we change the rear cassette to get some lower gears it should make a great touring bike as well. Its fork is carbon.
I see that I've carefully hidden the Marin's disc by the bag on the handlebars

[Bren]

Here are some pictures of the Marin:-

[NewHorizon]

Thanks for taking the time to post these - I'm amazed at the disc on the Marin carbon fork - surely there must be a big chunk of alloy in there somewhere to hold it all together?! The Enigma fork is interesting, I see it has lugs for canti/V brakes as well. Is it all Ti inc the steerer? Do you know what the rake is? Is the bike the elusive and exclusive 'Excel'? Sorry for so many questions!

[Bren]

No problem about the questions NewHorizon- I only wish I could answer them
I don't know if there is an metal in the Marin fork, I don't think so having looked through the eyelet above where the speed sensor is.
I ended up with the Ti fork on the Enigma by default- originally I was told that it would come with a steel fork but I think that Enigma had supply problems and they designed their own. The ride comfort is amazing- road buzz has just disappeared.
I've no idea on the rake or whether the steerer is Ti or something else.

The bike was ordered as an Excel but it's been delivered with Etape logos. I see that the Excel has gone from the new Enigma web-site so perhaps they've withdrawn it.

[NewHorizon]

I made some enquiries abut the Excel last year, because there was so little info on Enigma's web site about it - was told that it was in fact a 'bespoke' model, each built to order to fit the rider. As you say, its disappeared from their 09 site, I suspect its still available as part of their 'LAB range. I'd be rather upset if my Excel arrived with Etape decals! I'll make some enquiries with them about a Ti fork - thanks for all your input.

[andyf]

would it be dangerous - or just plain silly - to compromise (for reasons of front fork, maintenance when on tour , etc etc as discussed above in this thread) and keep rim brakes on front while upgrading to disc on the back. Obviously it would be worth remembering which is which when braking!

[Si]

can't see it being dangerous - I've seen it done a few time on MTBs in the early years of discs. I do it the other way: I've a disc at front (where the mainstay of the braking is done) and rim brakes at the rear.

[EdinburghFixed]

Andy - I'm not sure why you'd want to upgrade the back brake only, when the front provides almost all the power.

My new bike is going to be disc up front, rim at the back - I didn't think it was worth having anything more than the most basic back brake (that's already enough to lock the wheel if I squeeze it too!).

It is difficult because it requires a disc fork. But from the first moment I tried a disc brake, I knew that was the future wherever I could fit one!

[djnotts]

I was never totally convinced of the benefits of discs until last weekend! Admittedly on an mtb and wet and definitely off-tarmac (CTC Derbys Tracks and Trails Hols), but the discs (only Avid Juicy 3s) on my Giant XTC were simply in a different class to any rim brakes I've ever used.
My next 700c wheeler - for whatever use - WILL have discs.

[NewHorizon]

would it be dangerous - or just plain silly - to compromise (for reasons of front fork, maintenance when on tour , etc etc as discussed above in this thread) and keep rim brakes on front while upgrading to disc on the back. Obviously it would be worth remembering which is which when braking!

Can't see how it would be dangerous, although I suspect you could lock the back wheel up quite easily if unladen. My Van Nicholas Amazon is disc ready at the rear but not at the front, which I find slightly baffling (particularly as the hub isn't), but many other manufacturers do the same, something to do with marketing I suspect.

[glueman]

I never used to believe the disc hype until I did an MTB challenge, admittedly in filthy conditions, and completely wore out a set of V-blocks. TBF even disc users were cooking their brakes but rim braking was virtually non-existent.
I went out and bought a bike with hydraulic discs shortly after. Also seen a chap's Marin hybrid out and about with XT kit and discs and that looks like it takes real abuse on the road. Maybe draw the line at back of beyond expedition tours but I'm quite impressed with disc brakes.

[EdinburghFixed]

I'm also factoring in the fact that I need to replace my front rim after just a year, this is the price for doing 35 miles a day to work, but it does now require a headache of rim buying (£££), spoke calculating and then the build!

Just buying a new disc for cheap on eBay and bolting it on, now that *massively* wins in comparison.