Ask B Rose – Thoughts On Road Disc Brakes
Industry tech legend B Rose is back with another dose of tech opinions. In this column B Rose lets us know his thoughts on mechanical disc brakes on road and cyclorcross bikes. It may not be what you want to hear.
Submit your own questions in the form at the end of the column.
Q:I hear a lot of hub bub about disc brakes on road and cyclocross bikes. People seem to either love it or hate it. What’s the word?
B Rose: The yin and yang of disc brakes; it is not as easy a question as you might think. I love disc brakes on my mountain bike. But there are limits even in love. One thing I can’t abide (get ready to object) is mechanical disc brakes. I know many of you just did a spit and asked, “Who is this joker?” But I have found that mechanical disc brakes have three major flaws (none of which you will admit to). One, they are almost always set up wrong. In all my years specializing in suspension and disc brakes (enough to be way old school) I can count on my fingers all the times someone has put a properly set up set of mechanical disc brakes in front of me.Two, at their worst possible set up, mechanical disc brakes are totally unsafe (it’s a rare situation but I can show you at least 3 examples of ways people roll the dice with their mechanical disc brakes). And finally, and this especially applies to road, touring and cross bikes, they feel like crap. Lets clamp a piece of metal between two more pieces of metal and string a piano wire between them and your hand. Yuck. I hold a pretty high standard and I hate that feeling; it’s bad on a mountain bike but even worse on a road or touring bike (or cyclocross if you are going fast enough). Hydraulic brakes damp the connection and you don’t feel every jerk and ping of the rotor in your lever.
Why did I take you through all that? Because mechanical discs are your main option right now. So for me that is strike one of the “discs on cyclocross” argument.
Strike two? Squeal. Cyclocross, road and touring bikes amplify the biggest issue with disc brakes in two ways. Speed and contamination. I personally feel, with no engineering background, that 700c wheels glaze the current offerings in disc brake pads over very quickly. I say 700c and not 29er because the bikes that refer to their wheel sizes as 700c are faster than your mountain bike or 29er. And contributing to squeal, contamination; you find it so plentifully on pavement. It’s an educated guess that most people use their road, touring and cyclocross bikes on the street. Streets are very oily and that kills disc pads! My favorite bike is now made in a disc version, and everyone I know with one complains about their discs squealing constantly. If your discs squeal until you replace you pads and clean the system then contamination is the issue and that is 100 times more likely on the street.
Strike three? The best thing about about disc 700c bikes is also the third strike for me. Wheel interchangeability. It’s really a terrible reason to do anything on a bike, but it is a total myth with discs. Fits fine, still needs adjusted every swap. Show me a mechanic whose heart doesn’t feel like it is being squeezed every time someone wants to non-permanently swap their disc wheels. So when it comes to swapping out your wheels; you know they are going to need to be readjusted, you know they are probably gonna squeal and in your heart you know the correct answer is just to, “run what you brung.” Wheel swapping is an idealistic idea that always ends in a set of unused wheels.
It’s fashion, and there is nothing wrong with that, but it is the wrong idea. Sorry. Commence fling of slings and arrows now.
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