Hey Guys and Girls
Can you put a brake on a non-machined wheel?
edit: and if so what is the effect on the wheel? for instance a deep v or track wheel
cheers
Yes.
They will just rub the paint off.
how long do you reckon it would take?
are we talking months or years?
weeks/months, depending.
Yes of course. However they won’t perform as well as a proper machined braking surface. And as el Brado says, they will rub the anodizing/paint so they might look a bit tatty…
taty indeed i did it and i willl never own a nmsw and brake onit again.
depends on how wet/gritty/muddy the roads you ride are.
and how good your brake pads are… how often you use them… etc etc
it looks like you tried to ‘rbber erase’ the ano/paint for a while then it ends up looking like a dirty machined sidewall. im sure if you were anal enough you could clean it up so that it looked like it was a MSW all along.
My Deep V’s weren’t machined nor are the retro Ambrosio’s I have on my road bike. The paint/anodizing wears off soon enough. Just use some decent brake pads.
what everyone else said, but also make sure there is a square surface for the brake pads to engage with.
ie: you could use brakes on non machined side wall Deep V’s because there is a square profile for the brake pads to be applied on, but not very successfully on B43’s or H+Son Formation Face rims (plus many others)
Can you use brakes at all on B43s? I want to get a set but also want to run a front brake, or am I better off getting a deep v with msw for the front?
i ran a brake on the front non machined deep v for a month or two and it worked perfectly fine,
cant be too sure on B43 rim though but if you really want to run a brake get a machined rim dude other wise it will eventually look crap i reckon
When chatting to my LBS about whether to get machined front or not he said there was something about some of the finishes like the anodising which actually insulated the metal of the rim resulting in it heating up too much. Hot brakes being less effective. The machined surface would allow direct air contact and quicker cooling. Not sure if its that much of an issue though really. Maybe for MTB running rim brakes on an anodised rim.
I’ve never heard of rim brakes getting warm, let alone hot. If they got too hot the rubber pads would just melt off and be useless.
Disc brakes can get hot on long descents and can lose some of their braking power, but not anywhere near enough to be a problem.
The main reason rim walls are machined (as far as I’m aware) is to provide a smooth surface so that brakes don’t grab.
They can get hot enough to boil water given enough load or descending. This can lead to the tyre blowing off, or tubular glue melting.
Machining increases surface roughness and reduces squeal / increases braking efficiency.
Here’s some reading for you:
and then they faaaade
which I learned about on Mt Buninyong as a boy.
in the days of chrome rims and india rubber.
^^
Jobst suggested that the clincher tyre blew off the rim due to excessive pressure caused by increased temperature. The problem of tubular glue melting seems more plausible to me.
A simple application of G.ay–Lussac’s law: if a tyre has pressure of 120psi at room temperature (~23 deg C), then an increase in temperature to 120 deg C (suggested by Jobst but apparantely excessive 1,2) will increase the tyre pressure to only 160psi.
Since we are referencing Sheldon:
Most tires have a “maximum” pressure, or a recommended pressure range marked on the side of the tire. These pressure ratings are established by the tire manufacturers after consultation with the legal and marketing departments.The legal department wants the number kept conservatively low, in case the tire gets mounted on a defective or otherwise loose fitting rim. They commonly shoot for half of the real blow-off pressure.
If Sheldon is to be believed, and the tyre, correctly fitted to a good rim, is rated to a lowly 120psi, then the temperature would have to get up to 325 deg C to cause the tyre to blowoff/fail - at 240 psi.
So, who’s wrong, Sheldon or Jobst? 
Physics aside, I’ve still never heard of rim brakes heating up enough to cause problems. If it isn’t a problem for the pros descending the Alps (which is the situation Jobst attributes such blow outs to), I doubt it’s going to be a problem for anyone on the forum, regardless of MSW or not. I remain unconvinced.
However, thank you for increasing my awareness of why braking surfaces are machined.
At the moment, yarchive linkee no workee
1
2
Front rim temperature peaked between 175F and 200F
= 93 deg C… getting closer!
google Joseba Beloki, Bastille day (14 July) 2003.
Beloki hit the rear brake, locked up his wheel, and the pavement gave way beneath him. He fishtailed left, right and left again before going down.
but when he (Beloki) braked hard he locked up the back wheel and he couldn’t control it … then the back tyre rolled and exploded
And it was a tubular:
Still happy to be told otherwise, but if riding down hills caused your clincher tyre to ‘explode’ even on rare occasions, I think we’d be much more aware of it.
I’m not saying tyres never ‘explode’ when riding down hills, but that it doesn’t happen systematically in normal riding.