Bicycle Stopping Distances

RicodJour wrote:

On Nov 7, 11:48*pm, birdbrain wrote:
On Nov 7, 7:01*pm, RicodJour wrote:
On Nov 7, 9:42*pm, MagillaGorilla wrote:

But the front brake...it is essential that it is mounted to the front of the
fork.

http://www.bikeradar.com/gallery/art...-evans-silence...

Maybe you should save the Cervelo engineers a lot of embarrassment and
give them a call to straighten them out.

Just keep digging, Sponge Bob.

Dumbass, that's a time trial bike.

Excellent. Your eyes are functioning.
Your point being...what?
That the brakes aren't applied as often? True.
That it's unlikely that someone will be screaming downhill at 100 KPH
on it? Also true.

How does that change things?

It changes the only 2 things that really matter, dumbass.



Any braking force beyond locking up the
wheel is pointless. Do you doubt that the brake mounted in that
position would lock up the front wheel?

On a 55 mph descent with maximum braking, with a 250 pound rider the Cervelo design
would fail in a mean time that is 3x faster than if it were mounted on the front.
Also, you would probably get into problems with the brake pads migrating up towards
the tire under heavy loads whereas if it was mounted on the front it wouldn't do
that. Also, if you mount it on the front of the FORK, your front wheel will lock up
earlier and with less braking force than if you use the Cervelo design.. So the
QUALITY of braking is better (faster and easier) if you put the calipers on the front
when braking under HIGH LOADS.

Engineers talk about quality, stability, and longevity of a design, not just YES/NO
in terms of functionality. Mounting the calipers on the front of the fork is a much
better design in terms of those qualities.





Massengill stated an absolute, and he's absolutely full of ****. I
am performing my civic duty by pointing this out.

You're welcome.

R

Stop acting like an asshole in here.

Magilla

birdbrain wrote:

On Nov 7, 9:26*pm, RicodJour wrote:
On Nov 7, 11:48*pm, birdbrain wrote:

On Nov 7, 7:01*pm, RicodJour wrote:
On Nov 7, 9:42*pm, MagillaGorilla wrote:

But the front brake...it is essential that it is mounted to the front of the
fork.

http://www.bikeradar.com/gallery/art...-evans-silence...

Maybe you should save the Cervelo engineers a lot of embarrassment and
give them a call to straighten them out.

Just keep digging, Sponge Bob.

Dumbass, that's a time trial bike.

Excellent. *Your eyes are functioning.
Your point being...what?
That the brakes aren't applied as often? *True.
That it's unlikely that someone will be screaming downhill at 100 KPH
on it? *Also true.


So you're admitting that front mounted front brakes are superior?

Proof of this is that Cervelo mounts the brakes on the FRONT of the fork on its road
bikes....

http://bicyclebananas.com/mm5/mercha...ervelo_09_R 3

How do you like them bananas,

Magilla

MagillaGorilla wrote:
RicodJour wrote:

On Nov 7, 4:28 pm, "
wrote:
On Nov 7, 6:44 am, MagillaGorilla wrote:

Correct, but when it's pulling away from the stays, the only thing keeping it there is
the mounting bolt. All the stress of the braking is transfered through the mounting
bolt and nut. The bolt itself bends and is not inelastic. And the hold that the bolt
goes through is not perfectly flush with the bolt. But on the front brake, the entire
brake caliper assembly is being forced into the frame which is for the most part
immovable and thus gives better stability.
I get a ****ing headache every time I read that. I don't have my
stupid-to-English translator engaged, so tell me this, Batbuoy, are
you arguing that a loose brake bolt is what makes the difference? If
not, and the braking force is the same, as it must be, and all braking
force is transmitted to the frame, as it must be, where does this
extra braking force come from? The bolt, submitted to the same force
in either mounting position, will deflect the same amount as the
difference in geometry is negligible. Much like your argument.

No no no no. The front brake transfers most of the force through the mating surface of the
caliper to the FORK. The front bolt transfers probably 30% of the force. On the rear brake,
the bolt transfers nearly 100% of the force. It is true that all the force is ultimately
absorbed by the frame. But the design of the front bake via its placement on the front of the
FORK makes it a more stable design under high loads and high speeds. Ask any frame
builder/engineer.

Harry Havnoonian is a frame builder AND mechanical engineer (degree from Drexel). He mounts
the rear brake in front of the seat stays for this very reason and has been doing it for over
20 years. Give him a call and he'll tell you why:

http://www.hhracinggroup.com/page6.html





Talk to any frame builder or any engineer at Shimano or Campy or SRAM and they will all
tell you this. Most good mechanics know this too.
Here's the deal, you work up a free body force diagram and post it,
and I'll get on the horn and talk to Campy. I'll spare your other
little Mr. Softy - you don't even have to plug in numbers, just show
the arrows for the force vectors.

Why can't you just envision it - this is not a hard test.....Call Harry and ask him:

http://www.hhracinggroup.com/page6.html




The
mounting bolt will bent toward the wheel when it's mounted on the rear of the stay
and bend away from the tire when it's mounted on the front of the stay.
Again with the loose terminology - it's deflecting, and the amount is
truly miniscule.

Correct, except in your front brake, most of the force is transfered into the frame
which is for the most part an immovable object. On the rear brake, the brake caliper is
being pulled into the air away from the frame.
That doesn't matter as long as it doesn't get pulled off
the frame. It's still transferring the force to the frame.

Correct. But remember what we're arguing here....I'm only saying the front brake is a more
STABLE design and can take higher loads before it fails. The rear brake is a less stable
design (due to where it's mounted) and will fail earlier and offer less stability under maximum
load. Your rear brake will not feel as tight as your front brake if you do a max brake effort
from 55 mph going downhill. It matters more in tandems where the brakes must take double the
normal load over along period of time. And it's also more important for heavy riders,
especially if they go down major descents and need to stop fast.

Another Liz Hatch slam?



Brake bolts are sufficiently large diameter (M6) that they
don't bend significantly in normal use. This is good,
because if your brake bolt bends repeatedly when
you apply the brakes normally, it will eventually fail from
metal fatigue, and then you will be up monkey **** creek.

Bent brake bolts happen, but mostly from poor
maintenance, like beater bikes that people ride
around with the bolt loose and sticking out so there's
a bigger lever arm on it. Fortunately people who
ride these bikes (undergrads, DUI guys etc) rarely
go fast enough to do full on panic stops and snap
the bolt.

(snip MG drivel)
If you have a problem with braking like this, that isn't going
to help, because if you brake enough to plastically bend the
bolt, let alone pull it away from the frame, you're in trouble.
What you need in those circumstances, and what some
tandem riders use, is a third brake (rear drum).

Only a faggot would ride a bike with a drum brake on it.

Magilla

thirty-six wrote:

On 8 Nov, 02:42, MagillaGorilla wrote:
" wrote:
On Nov 7, 6:44*am, MagillaGorilla wrote:

Correct, but when it's pulling away from the stays, the only thing keeping it there is
the mounting bolt. * All the stress of the braking is transfered through the mounting
bolt and nut. The bolt itself bends and is not inelastic. And the hold that the bolt
goes through is not perfectly flush with the bolt. *But on the front brake, the entire
brake caliper assembly is being forced into the frame which is for the most part
immovable and thus gives better stability.

Talk to any frame builder or any engineer at Shimano or Campy or SRAM and they will all
tell you this. * Most good mechanics know this too.

The
mounting bolt will bent toward the wheel when it's mounted on the rear of the stay
and bend away from the tire when it's mounted on the front of the stay.

Correct, except in your front brake, most of the force is transfered into the frame
which is for the most part an immovable object. *On the rear brake, the brake caliper is
being pulled into the air away from the frame.

That doesn't matter as long as it doesn't get pulled off
the frame. *It's still transferring the force to the frame.

No, it does matter. *The front brake transfer most of its force to the face of the FORK that
mates with the calipers. *The rear brake, the forces are transferred only to the nut threads
and the end of the bolt that holds the brake calipers. *The front brake has more lateral
stability because the brake caliper is being pressed super-hard against the frame whereas the
rear brake is being pulled away from the frame and held onto the bike only by the threads on
the nut. *The caliper moves less on the front brake under maximum load. *The rear brake
design can't away with it because the loads are less than on the front brake by a factor of 3
and the rear brake design - even with the mounting deficiency - is still sufficient to lock
up the wheel. *But the front brake...it is essential that it is mounted to the front of the
fork.

If you could somehow mount your front brake to the rear of your fork, and then did maximum
braking on a 55 mph descent, you would eventually see some catastrophic front brake failures
in the peloton over the course f a few years unless gruppos companies beefed up the mounting
bolts.



Brake bolts are sufficiently large diameter (M6) that they
don't bend significantly in normal use. *This is good,
because if *your brake bolt bends repeatedly when
you apply the brakes normally, it will eventually fail from
metal fatigue, and then you will be up monkey **** creek.

The rear bolt is under 3x less load than the front bolt during a maximum braking effort at
high speed. *So this is why the M6 can take the beating and keep on ticking. *However, if you
put that same load on the front brake which is subject to 3x the load of the rear brake, you
would eventually see bolt failures. *But because most of the load on the front brake is
transferred to the FORK, the bolt is spared the beating it would get had the front brake been
mounted to the rear of the fork as the rear brake is mounted to the seat stays.





Bent brake bolts happen, but mostly from poor
maintenance, like beater bikes that people ride
around with the bolt loose and sticking out so there's
a bigger lever arm on it. *Fortunately people who
ride these bikes (undergrads, DUI guys etc) rarely
go fast enough to do full on panic stops and snap
the bolt.

If you are a 250 pound rider (or a tandem bike) and routeinly go down 55 mph descents
and need to stop, you would want your rear brake mounted opposite of where it
normally is.

If you have a problem with braking like this, that isn't going
to help, because if you brake enough to plastically bend the
bolt, let alone pull it away from the frame, you're in trouble.
What you need in those circumstances, and what some
tandem riders use, is a third brake (rear drum).

Ben

Always use a superior design and technique. *Never accept less than the best.

Magilla

You are wrong. Bending of sidepull mounting bolt is due to torque
upon the caliper arms caused from the drag of the brake pads upon the
rotating rim. If the bolt is made tight enough, this bending strain
does not take place.

Envision it this way....if you mounted the front brake on the rear side of the fork (like the
Cervelo TT bike)...under maximum load (say 250 lb rider, 55 mph descent, maximum braking effort to
avoid a guardrail)..the brake would be pulled away from the frame by a fraction of an inch,
creating lateral instability. If mounted on the front of the FORK, the calipers would not move
at all because a large surface area would be pressing against the fork , which is basically
immovable.

Over a long period of time, the Cervelo TT design is putting more stress on your parts than the
front-of-fork design. Since bike parts are made to trade best design for weight, you can use
lighter weight bolt with the front design and still have it be more stable than a heavier bolt in
a rear-mount.

If you are telling me the bolt can take 3x the load when mounted on the rear of the fork, then you
are also admitting that you pushing the envelope of failure EARLIER. Any design that puts less
load on the parts is considered a better design. And you can in fact design a bolt that is
lighter and offers more of a safety envelope simply by mounting the calipers of front brake on the
FRONT of the fork.

Engineers take things like durability, mean time to failure, and fail-safe loads into
consideration. Your mistake is you are claiming simply because the brake "will work" regardless
of where it's mounted it is mounted (you are correct) is an equally good design (you are wrong).
You are wrong because any engineer will tell you that you are not looking at all the variables
that must be assessed in component designs:

- mean time to failure would increase if mounted on the rear of FORK, thus a heavier bolt must be
used than if mounted on the front
- less lateral stability if mounted on rear of fork under high loads
- in rear fork mounted brakes, bolt would have to be made heavier to endure the same loads that a
bolt would be subjected to if the calipers were mounted on the front of the fork, thus the part is
heavier and not safer.

A rear mounted brake on the fork would fare poorer in those 3 above categories (weight, stability,
and mean time to failure) than those same calipers had they been mounted on the front of the
fork. See what I'm saying? And as a result of that, you can make the bolt of a front mounted
brake LIGHTER while still having an even greater safety envelope (and longer mean time to failure)
than if you used a heavier bolt and mounted the calipers on the rear.

Your design concept fails to take into consideration the things that are very important to
engineers who make high end gruppos and are always trying to push the envelope with weight vs.
safety/durability.

Magilla







Magilla

RicodJour wrote:

On Nov 7, 10:02*pm, thirty-six wrote:

Bending of sidepull mounting bolt is due to torque
upon the caliper arms caused from the drag of the brake pads upon the
rotating rim. *If the bolt is made tight enough, this bending strain
does not take place.

That is not strictly true. If you model the break bolt as a
cantilevered beam, the bolt tightness is analogous to post
tensioning...partial post tensioning. The tightness of the bolt will
affect the deflection, and the bolt between the mounting contact
points will deflect. The deflection with a properly tightened bolt is
totally negligible and could never be a factor by the time you lock up
the wheel.

More to the point Maxipadilla has no idea what he is talking about,
and, if he in fact has had conversations with bike engineers on the
topic, he had no idea what they were talking about. That much is
clear.

R

Dude,

It's you who don't know what you are talking about.

Magilla

" wrote:

On Nov 7, 7:42*pm, MagillaGorilla wrote:

No, it does matter. *The front brake transfer most of its force to the face of the FORK that
mates with the calipers. *The rear brake, the forces are transferred only to the nut threads
and the end of the bolt that holds the brake calipers. *The front brake has more lateral
stability because the brake caliper is being pressed super-hard against the frame whereas the
rear brake is being pulled away from the frame and held onto the bike only by the threads on
the nut. *The caliper moves less on the front brake under maximum load. *The rear brake
design can't away with it because the loads are less than on the front brake by a factor of 3
and the rear brake design - even with the mounting deficiency - is still sufficient to lock
up the wheel. *But the front brake...it is essential that it is mounted to the front of the
fork.

ENGLISH PLEASE.

Where does the force go after it's transferred
to the rear brake bolt and nut? It doesn't magically
leak out into the air before being transferred to the
seat stay brake bridge.

The nut is plenty strong enough. If those nuts weren't
strong enough, front brakes would come flying off of
forks all the time. In fact, this reminds me that you
have it backwards. The front brake bolt is under
tension and is held on by the nut, while the rear
brake is compressed against the seat stays.
You can argue all you want about whether bolts and
nuts are stronger in compression or tension, I don't
care, as both are clearly strong enough in use.

I don't even remember why you started this pointless
argument about brakes, and you don't remember enough
to be consistent in the arguments you're making.

Ben

Shut up you idiot.

Magilla

RicodJour wrote:

On Nov 8, 4:12*am, "
wrote:
On Nov 7, 7:42*pm, MagillaGorilla wrote:

No, it does matter. *The front brake transfer most of its force to the face of the FORK that
mates with the calipers. *The rear brake, the forces are transferred only to the nut threads
and the end of the bolt that holds the brake calipers. *The front brake has more lateral
stability because the brake caliper is being pressed super-hard against the frame whereas the
rear brake is being pulled away from the frame and held onto the bike only by the threads on
the nut. *The caliper moves less on the front brake under maximum load. *The rear brake
design can't away with it because the loads are less than on the front brake by a factor of 3
and the rear brake design - even with the mounting deficiency - is still sufficient to lock
up the wheel. *But the front brake...it is essential that it is mounted to the front of the
fork.

ENGLISH PLEASE.

Where does the force go after it's transferred
to the rear brake bolt and nut? *It doesn't magically
leak out into the air before being transferred to the
seat stay brake bridge.

The nut is plenty strong enough. *If those nuts weren't
strong enough, front brakes would come flying off of
forks all the time. *In fact, this reminds me that you
have it backwards. *The front brake bolt is under
tension and is held on by the nut, while the rear
brake is compressed against the seat stays.
You can argue all you want about whether bolts and
nuts are stronger in compression or tension, I don't
care, as both are clearly strong enough in use.

I don't even remember why you started this pointless
argument about brakes, and you don't remember enough
to be consistent in the arguments you're making.

I'm suprised Myra didn't convince you with "The front brake has more
lateral stability because the brake caliper is being pressed super-
hard against the frame". Can't you read?! SUPER-hard!*

R

* The ball is lobbed high in the air, and...

You need to wash out your Fleshlight, pal.

Tom Kunich

On 9 Nov, 21:50, MagillaGorilla wrote:
thirty-six wrote:
On 8 Nov, 02:25, MagillaGorilla wrote:

Use Phil grease, not oil.
I use a combination of cacium grease which is loaded when the need
arises with cycle oil. *Works well. *Saves having to dissasemble each
year. *I think its ten years(at least) since taking apart my bottom
bracket. *Still running sweet.

Don't make mistakes. *That what Lance tells his mechanic. *You need to treat yourself like Lance's treats his mechnic and
you'll be fine. *Don't be a pussy.

The quicker I can perform a service item the more reliable it's going
to be. *I'm always looking for shortcuts. *Fewer steps reduce the
likelyhood of tripping up.

You sound like a mechanic who works for Alaska Airlines in 2000. *Let me give some advice...if the directions that came with
the part tells you to lube the jackscrew every 2,000 hours, lube the ****ing jackscrew. *Don't give me any of this jazz about
how many steps there are. *Just do it.

Never seen any manufacturers brake servicing instructions. I have
enough experience to know how long the lubricants I install remain
effective. The checks I make, guarantee that aghh bollox

z wrote:

MagillaGorilla wrote:
RicodJour wrote:

On Nov 7, 4:28 pm, "
wrote:
On Nov 7, 6:44 am, MagillaGorilla wrote:

Correct, but when it's pulling away from the stays, the only thing keeping it there is
the mounting bolt. All the stress of the braking is transfered through the mounting
bolt and nut. The bolt itself bends and is not inelastic. And the hold that the bolt
goes through is not perfectly flush with the bolt. But on the front brake, the entire
brake caliper assembly is being forced into the frame which is for the most part
immovable and thus gives better stability.
I get a ****ing headache every time I read that. I don't have my
stupid-to-English translator engaged, so tell me this, Batbuoy, are
you arguing that a loose brake bolt is what makes the difference? If
not, and the braking force is the same, as it must be, and all braking
force is transmitted to the frame, as it must be, where does this
extra braking force come from? The bolt, submitted to the same force
in either mounting position, will deflect the same amount as the
difference in geometry is negligible. Much like your argument.

No no no no. The front brake transfers most of the force through the mating surface of the
caliper to the FORK. The front bolt transfers probably 30% of the force. On the rear brake,
the bolt transfers nearly 100% of the force. It is true that all the force is ultimately
absorbed by the frame. But the design of the front bake via its placement on the front of the
FORK makes it a more stable design under high loads and high speeds. Ask any frame
builder/engineer.

Harry Havnoonian is a frame builder AND mechanical engineer (degree from Drexel). He mounts
the rear brake in front of the seat stays for this very reason and has been doing it for over
20 years. Give him a call and he'll tell you why:

http://www.hhracinggroup.com/page6.html





Talk to any frame builder or any engineer at Shimano or Campy or SRAM and they will all
tell you this. Most good mechanics know this too.
Here's the deal, you work up a free body force diagram and post it,
and I'll get on the horn and talk to Campy. I'll spare your other
little Mr. Softy - you don't even have to plug in numbers, just show
the arrows for the force vectors.

Why can't you just envision it - this is not a hard test.....Call Harry and ask him:

http://www.hhracinggroup.com/page6.html




The
mounting bolt will bent toward the wheel when it's mounted on the rear of the stay
and bend away from the tire when it's mounted on the front of the stay.
Again with the loose terminology - it's deflecting, and the amount is
truly miniscule.

Correct, except in your front brake, most of the force is transfered into the frame
which is for the most part an immovable object. On the rear brake, the brake caliper is
being pulled into the air away from the frame.
That doesn't matter as long as it doesn't get pulled off
the frame. It's still transferring the force to the frame.

Correct. But remember what we're arguing here....I'm only saying the front brake is a more
STABLE design and can take higher loads before it fails. The rear brake is a less stable
design (due to where it's mounted) and will fail earlier and offer less stability under maximum
load. Your rear brake will not feel as tight as your front brake if you do a max brake effort
from 55 mph going downhill. It matters more in tandems where the brakes must take double the
normal load over along period of time. And it's also more important for heavy riders,
especially if they go down major descents and need to stop fast.

Another Liz Hatch slam?

Nice. Take that, Lizard.

Magilla

On Nov 9, 3:18*pm, MagillaGorilla wrote:
RicodJour wrote:
On Nov 7, 4:28*pm, "
wrote:
On Nov 7, 6:44*am, MagillaGorilla wrote:

Correct, but when it's pulling away from the stays, the only thing keeping it there is
the mounting bolt. * All the stress of the braking is transfered through the mounting
bolt and nut. The bolt itself bends and is not inelastic. And the hold that the bolt
goes through is not perfectly flush with the bolt. *But on the front brake, the entire
brake caliper assembly is being forced into the frame which is for the most part
immovable and thus gives better stability.

I get a ****ing headache every time I read that. *I don't have my
stupid-to-English translator engaged, so tell me this, Batbuoy, are
you arguing that a loose brake bolt is what makes the difference? If
not, and the braking force is the same, as it must be, and all braking
force is transmitted to the frame, as it must be, where does this
extra braking force come from? *The bolt, submitted to the same force
in either mounting position, will deflect the same amount as the
difference in geometry is negligible. *Much like your argument.

No no no no. *The front brake transfers most of the force through the mating surface of the
caliper to the FORK. *The front bolt transfers probably 30% of the force. *On the rear brake,
the bolt transfers nearly 100% of the force. *It is true that all the force is ultimately
absorbed by the frame. *But the design of the front bake via its placement on the front of the
FORK makes it a more stable design under high loads and high speeds. *Ask any frame
builder/engineer.

Harry Havnoonian is a frame builder AND mechanical engineer (degree from Drexel). *He mounts
the rear brake in front of the seat stays for this very reason and has been doing it for over
20 years. *Give him a call and he'll tell you why:

http://www.hhracinggroup.com/page6.html


Jesus Christballs.

When a bike moves FORWARD the top of the rim
is moving FORWARD and when you brake, the frictional
force of the rim on the brake tries to pull the brake
FORWARD. You appear to be pedaling your monkey-bike
BACKWARD. Are you a fixed gear hipster, or worse yet,
a trackie? What do trackies know about brakes anyway?

The front brake is pulling on the bolt - the entire force
is on the bolt. The rear brake when conventionally
mounted is pushed against the seatstay by the braking
force.

I could see making some kind of argument that turning
the brake around would load the structure of the brake
in tension and reduce brake squeal, but with modern
road brake arms that don't flex much (not skinny old
inferior Campy competitors from the 60s) and proper
brake pad toe-in, this is not an issue.

Ben