It’s been pointed out to me twice in the last 24 hours that this place has become too silent.  I’ve been struggling with blogger’s block of late if I’m honest.  Still out there riding, sweating and swearing but when I sit down here, the day evaporates and I find myself reading the things I said I wouldn’t and not writing anything.

I’ve managed to avoid the “this piece of laser-guided, alien-inspired carbon-billet doo-daddery that weighs precisely 3 french fries less than your current one is a must-have at only $1500″ pseudo magazine articles however in my on-going dithering about a new bicycle, I’ve been scouring the internet endlessly.

The Stevens Carbon Team in all it’s Germanic perfection…without disc brakes sadly.

After 10 days of waiting, the you need to show more interest than going down there 3 times to tell them you’re interested before they’ll respond to you bike shop finally responded to my subsequent interest-expressing email with a very reasonable quote on a Stevens Carbon Team frame build.  It was good enough to pique my interest despite the lack of one of my key want features – disc brakes – but their so-low-pressure-sales-we-won’t-do-anything schtick eventually wore me down and I moved on.    Just as well, I want those disc brakes.  In my three previous interest-expressing trips, I’d expressed my desire for a Stevens Vapor – the only one with discs – but was eventually told via Guru Thomas that they wouldn’t order it because they didn’t want to get stuck with it.  I’m not going beg you to take my money…

Now disc brakes on bikes are the subject of all sorts of internet and bike-shop debate from the barely reasonable – they add weight to the utterly ridiculous – they’re too powerful and lots of inexperienced riders will crash after they lock up their front wheel while blazing down the mountain pass in the rain.  Yeesh.

In fairness, they are heavier – about 300 grams to go from cantilever to disc.  Less than a 2nd water bottle.  I’m not in the pro or amatuer or any peloton nor do I see the 300 grams of extra brake as a deal-braker when I’ve got an easy 3000 10,000 grams around my middle I could shed.  The latter argument – too much power – doesn’t warrant an actual rebuttal it’s so utterly cockamamy.

I would like to comment on another reason I’ve been given to avoid disc brakes – they’re not hydraulic.   Disc brakes come in two fashions – mechanical/cable operation or hydraulic operation.  If I was given the choice, I’d certainly pick hydraulic over cable.  At the moment there is precisely one manufacturer making a hydraulic brake system for road/’cross bikes (yet numerous for mountain, this due to the UCI – the cycling version of the FIA, only just approving discs for cyclocross bikes) and they’ve not released anything to the public yet, rather continuing to work with Colnago on their beautiful C59 road bike.  I’m not sure which would cost more however – the C59 or the divorce that would inevitably result subsequent to it’s purchase.

Mechanical/cable versions are very simple – pulling the brake lever pulls a cable.  The other end of the cable is attached to a lever that is attached, for the purposes of illustration, to a threaded ram.  Pulling on the cable pulls the lever which causes the ram to rotate, which causes it to move in towards the disc by virtue of the thread.   A brake pad is mounted to the end of the ram and thus when the ram is rotated inwards, it pushes the pad into contact with the disc.  Bicycle brake discs are thin (1.5mm or ~0.060″) and somewhat flexible so as the pad is pushed into it from one side, it flexes away from the pad and makes simultaneous contact with a pad on the opposite side, ultimately sandwiched between the two pads.  A spring on the ram rotates the pad/ram/lever assembly back out when the lever is released and the disc, now unstressed by the pad, returns to it’s previous position, no longer contacting the inside pad.

Absolutely simple and quite effective – certainly more effective, and more importantly impervious to the elements than any rim brakes currently available.  Granted, it’s subject to cable-related issues – stiction, cable stretch and jacket collapse among others.  These issues have existed since motorcycles were introduced as they’ve used, for a century or so, cables for operation of the clutch, throttle and even early drum brakes.  Mechanical brakes also require consistent maintenance as there is no automated means to compensate for pad and disc wear.  This takes all of 5 minutes every Sunday evening as I prep the Rescue Bike for another week of riding.  If I get around to it (the maintenance that is).

Hydraulic brakes function like scaled-down versions of motorcycle brakes.  Powerful, linear, exceptional and capable of both tremendous stopping power and remarkable modulation.  Using the principle of Pascal’s law, they use fluid under pressure in place of a cable and a piston (or pistons) in place of the ram.  The spring is replaced by a deformable D-ring seal – the D shape of the seal allows the piston to slide out while deforming slightly as the piston, under pressure from the fluid, pushes towards the disc.  That seal deformation in combination with subtle piston-chamber design pulls the piston away from the pad (and thus disc) when the brake lever is released.  Hydraulic discs are more refined than mechanical to be sure – you don’t have to adjust them for wear – the action of the D-rings seals and piston motion serve to automatically adjust position every time they’re used though a dirty or poorly maintained setup will drag the pads on the disc.  They’re powerful, far more so than mechanical and infinitely more than rim brakes.  Their single drawback (in my eyes – I don’t care much about weight or being too powerful after all) is the brake fluid.  When it’s clean and bled properly, there’s no issue but air in the system can be a nightmare to get out.  This isn’t a use issue of course, just maintenance related.  Take care of them and they’ll take care of you.

So if a rider wants to step into a road or cyclocross bike, wants disc brakes and wasn’t born into a family of investment bankers, the choice today remains mechanical/cable.  Amusingly, those that would advise me to fore-go the mechanical discs because they’re only cable, not hydraulic somehow miss entirely that the rim brakes they’re admonishing us to stick with are – yup – cable operated.

In the event you’re confused by the cyclocross reference, see here.  An insanity originating in Belgium it involves pavement, mud, grass, snow perhaps, steep climbs,cow bells and barriers that require you to carry your bike.  The course is unrideable by design – but it’s spawned the ultimate do-everything bike.