A newb question

The foundations for successful riding

Re: A newb question

Postby steambao » Sun Nov 01, 2009 11:45 pm

Kalgrm wrote:
toolonglegs wrote:Oh well we will have to agree to disagree on that one... :D

I'm with you on this one TLL. Under steambao's theory, we'd never be able to coast on our bikes.

Steambao, the wheel only slows significantly when the brakes are applied. If you release the brakes, the only thing slowing you is rolling and wind resistance, which is there whether you've got the brakes applied or not.

Cheers,
Graeme


It's not my theory. It was my physics teacher's theory!! But he was the one marking my paper :mrgreen:
This topic is still very interesting and I believe both methods have pros/cons in certain situations. I'm going to put my life on the line in the name of science and run a test on this :P

But now I want to get hydraulic brakes because I've never seen those in action before. Is it true that hyrdaulics is all power or nothing?
Image
User avatar
steambao
 
Posts: 188
Joined: Mon Oct 12, 2009 12:45 am
Location: Banyule, N.E. Melbourne

by BNA » Mon Nov 02, 2009 4:21 am

BNA
 

Re: A newb question

Postby Kalgrm » Mon Nov 02, 2009 4:21 am

steambao wrote:But now I want to get hydraulic brakes because I've never seen those in action before. Is it true that hyrdaulics is all power or nothing?

No, it's not true unless the brakes are particularly poorly designed. Good hydraulic brakes have good modulation and heaps of stopping power. It's possible to control the braking from almost nothing to fully locked with only one finger with good brakes.

This is important because if you're flying down hill on a very rough patch of rocky single track on your MTB, you want three fingers and your thumb gripping the bars for steering and one finger to slow you with control.

cheers,
Graeme
Think outside the double triangle.
---------------------------------------
My web site: www.scenebyhird.com
---------------------------------------
The Bicycle Transportation Alliance
User avatar
Kalgrm
Super Mod
Super Mod
 
Posts: 9236
Joined: Fri May 25, 2007 5:21 pm
Location: Spearwood, 9km SE of Fremantle, WA

Re: A newb question

Postby Nobody » Mon Nov 02, 2009 7:48 am

steambao wrote:It's not my theory. It was my physics teacher's theory!!
So that's one way how misconceptions like this occur. If you really think that reducing your braking pressure momentarily is going help you brake faster, you need to test it for yourself before you get hurt in a difficult situation.

Releasing the brakes does help me on the MTB to regain grip once the wheel is already sliding. The only other time it is beneficial is to release mud from the pads.
Nobody
 
Posts: 6655
Joined: Thu Sep 18, 2008 12:10 pm
Location: Sydney

Re: A newb question

Postby Jonny Rochester » Mon Nov 02, 2009 8:57 pm

I just came back to this topic for a laugh, since I am a car mechanic and play with race cars at times.

Aside from just road bike brakes, consider the whole road bike setup. Your riding a road bike at 60km/h weighing only 8kg which will totaly collapse on impact, with the centre of gravity up near the roofline of most cars, feet stuck to the cranks with nothing but lycra undies for protection. It's bloody dangerous. Especially if you just buy the kit and go for it. And some beginners can't even reach the brake levers, or their weak muscles will be too fatuiged at the bottom of the hill. But for those fit and experienced, road bike brakes will be adequite. But it is far easier to just jump on a mountain bike.

On a long fast decent on my bike, I smoothly alternate between front and rear brakes a little. This is in fear the brake pads could overheat and get brake fade. Letting go of the brakes lets them cool.

At the moment I am working more on my bike setup. Handlebar position etc. The better I fit the bike and can corner it, the less I will have to use the brakes. Best not to use the brakes at all and just go fast. A road bike is a racing bike after all.
User avatar
Jonny Rochester
 
Posts: 86
Joined: Tue Sep 01, 2009 5:58 pm
Location: Hobart

Re: A newb question

Postby m@ » Tue Nov 03, 2009 9:23 am

Jonny Rochester wrote:I just came back to this topic for a laugh, since I am a car mechanic and play with race cars at times.

Aside from just road bike brakes, consider the whole road bike setup. Your riding a road bike at 60km/h weighing only 8kg which will totaly collapse on impact, with the centre of gravity up near the roofline of most cars, feet stuck to the cranks with nothing but lycra undies for protection. It's bloody dangerous. Especially if you just buy the kit and go for it. And some beginners can't even reach the brake levers, or their weak muscles will be too fatuiged at the bottom of the hill. But for those fit and experienced, road bike brakes will be adequite. But it is far easier to just jump on a mountain bike.

On a long fast decent on my bike, I smoothly alternate between front and rear brakes a little. This is in fear the brake pads could overheat and get brake fade. Letting go of the brakes lets them cool.

At the moment I am working more on my bike setup. Handlebar position etc. The better I fit the bike and can corner it, the less I will have to use the brakes. Best not to use the brakes at all and just go fast. A road bike is a racing bike after all.


Well, yeah... but a public road isn't a race track, hence there can be unexpected hazards. While in some ways I'd love to really let loose down some steep descents, there's just too much risk of a car pulling out from a driveway or a pedestrian stepping onto the road without looking/thinking...
User avatar
m@
Super Mod
Super Mod
 
Posts: 4514
Joined: Tue Apr 15, 2008 12:20 pm
Location: Northlandia

Re: A newb question

Postby X-ray » Sat Dec 26, 2009 4:58 pm

steambao wrote:Don't forget your HIGH SCHOOL PHYSICS.

What's the fastest and safest way to stop? Pump the brakes!! Your stopping distance will be the shortest if you pump (Press, release, roll, press, release, roll) because its the rolling resistance that slows you down the most. That's what you get in a Car with assisted braking :D

That way you can never flip over your bars too.


As others have said, pumping the brakes won't help you stop faster. Rather it will take longer to stop since the retardation force produced by the brakes is only applied intermittently.

To stop in the shortest distance you need to hold a braking pressure that is just shy of causing the wheels to lock. I'm not an expert on ABS in cars, but I believe an ABS system works by increasing the braking pressure until the wheels lock. Once the wheels lock the brakes are released and then applied again. It has to be done this way because the system can't know exactly what magnitude of braking pressure will cause the wheels to lock. Hence the 'lock-release' method.
Image
X-ray
 
Posts: 79
Joined: Sat Nov 21, 2009 9:18 am
Location: Wollongong, NSW

Previous

Return to Training

Who is online

Users browsing this forum: Bing [Bot]



Popular Bike Shops
Torpedo 7 Torpedo7 AU
Ground Effect Ground Effect NZ
Chain Reaction Cycles CRC UK
Wiggle Wiggle UK
Ebay Ebay AU

“Bicycles BNA Twitter
“Bicycles BNA Facebook
“Google+ BNA Google+
“Bicycles BNA Newsletter

> FREE BNA Stickers
> BNA Cycling Kit