Re: 140 front disc rotor
Posted: Tue Nov 07, 2017 12:05 am
Ability to lock the front wheel doesn't mean that you have to do it. You just use less force on levers and modulate the brake to you needs.
Forum
https://weightweenies.starbike.com/forum/
https://weightweenies.starbike.com/forum/viewtopic.php?f=3&t=148353
Cemicar wrote:Some forks are actually 160mm only. BMC's Teammachine SLR01, for instance.
uraz wrote:You are right, road disc brakes are not weak like for example u-brake on wet carbon clincher rim but they are not as strong as they could be.
Of course in normal day-to-day use I don't have to pull levers with unhumane force, they perform well (on pair with best conventional brakes setup or slightly better), but when I want/need all the braking power that my tires can handle, sram red hydroR can't deliver it. I had high hopes for road hydraulics and maybe this is a reason I'm not so satisfied with them. I like brakes that can generate force bigger than I would ever want to use. Front wheel locking point at 80% of total capability (something like shimano xt), not at 120%.
PS> I would be totally satisfied with 40% greater maximum power. Supposedly new sram hydroHC are stronger.
MoPho wrote:ITo the topic, I started with 140 f/r and weighed about 84kg and they were fine and had no issues, but made the switch to 160/140 (and then 160/160) and I thought the braking was much better. I'm now down to 72.5kg and don't feel like the 160's are overkill at all (per above). I have been recommending going to 160mm front to my friends regardless of weight.
uraz wrote:Ability to lock the front wheel doesn't mean that you have to do it. You just use less force on levers and modulate the brake to you needs.
Lewn777 wrote:[
I hope they aren't dumbing down road disks power in an attempt to protect people from themselves or they'll be a whole bunch of people switching out their front calipers for MTB calipers.
uraz wrote:Smaller pistons, smaller brake pads - no doubt they are making road discs weaker on purpose.
rpowell wrote:why does a smaller brake pad = less stopping power. i was taught in physics that frictional force is independent of surface area.
youngs_modulus wrote:[Snip]
CallumRD1 wrote:youngs_modulus wrote:[Snip]
Coming from a physicist, excellent post!
CallumRD1 wrote:I'd just like to emphasize a few points. First of all, the diameter of the rotor will affect the stopping power of a braking system, all else being equal.
<snip>
Secondly, while it is generally true that the force due to friction is independent of surface area, it is not always true.
<snip>
That being said, the brake pad compounds used on bikes and cars are sufficiently hard to nearly completely negate this failure mode, so it's not particularly relevant to this discussion.
CallumRD1 wrote:Finally, a point that many proponents of rim brakes fail to grasp is that [μs > μk].
youngs_modulus wrote:So yeah, mountain bikes don't have more stopping power because their tires are bigger. Once your brake is strong enough to lift the rear wheel--on road or off--max stopping power is dictated by where your center of mass is. Low and far behind the front wheel is what you want here...this is why tandems can stop faster than single bikes.