Drum Brake: Different Lever?

[(PeteCresswell)]

The spokes arrived and, somehow, I managed to stumble through
lacing and truing a drum-braked front wheel.

I'm jazzed. Cleans up the bike more than I expected.
Maybe I'm a closet single-speeder.

Now I'm wondering about the braking strength.

Understood that drum brakes aren't renowned for their braking
power, but:
-----------------------------------------------------------
1) I have an image of a true metal drum with a couple of
not-so-true brake shoes that need to wear in for awhile before
they expose all of their surface to the drum.

Any validity in this image?


2) I've read that disc brakes need a certain amount of hard
stopping to deposit something-or-other from the pads onto
the discs to realize max performance.

Anything like that with drum brakes?


3) I'm using the same lever I used for my v-brake. The lever
has two positions. One is less bad than the other, but
it still seems like too much grip strength is required.

Could there be (no pun intended) a leverage issue?
-----------------------------------------------------------
--
PeteCresswell

 

[landotter]

On Feb 29, 8:58 pm, "(PeteCresswell)" <[email protected]> wrote:

> 3) I'm using the same lever I used for my v-brake. The lever
> has two positions. One is less bad than the other, but
> it still seems like too much grip strength is required.
>
> Could there be (no pun intended) a leverage issue?

Ja--v-brake levers pull too much cable with little force, relying on
the brake arm length for mechanical advantage. You might just need a
set of regular pull levers is all. Cheap.

Now, if you have levers with adjustable pull already--it might just be
a matter of break-in. Chose the least shitty position and give it a
few miles.

 

[(PeteCresswell)]

Per landotter:
>Chose the least shitty position and give it a
>few miles.

That's my plan.

On the way to where I do most of my recreational riding, there's
a fairly steep hill - maybe 3/4 mile long. I figure a few trips
down that should resolve any wear-in issues.
--
PeteCresswell

 

[A Muzi]

(PeteCresswell) wrote:
> The spokes arrived and, somehow, I managed to stumble through
> lacing and truing a drum-braked front wheel.
> I'm jazzed. Cleans up the bike more than I expected.
> Maybe I'm a closet single-speeder.
> Now I'm wondering about the braking strength.
> Understood that drum brakes aren't renowned for their braking
> power, but:
> -----------------------------------------------------------
> 1) I have an image of a true metal drum with a couple of
> not-so-true brake shoes that need to wear in for awhile before
> they expose all of their surface to the drum.
> Any validity in this image?
> 2) I've read that disc brakes need a certain amount of hard
> stopping to deposit something-or-other from the pads onto
> the discs to realize max performance.
> Anything like that with drum brakes?
> 3) I'm using the same lever I used for my v-brake. The lever
> has two positions. One is less bad than the other, but
> it still seems like too much grip strength is required.
> Could there be (no pun intended) a leverage issue?

Yes, most brakes 'bed in'; that is, detritus and surface imperfections
get abraded away in the first few miles. Drums do that, too.

Your levers should be in 'normal' mode not 'linear' [V] mode for a drum
brake. Less travel, more leverage.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

 

[dabac]

3) I'm using the same lever I used for my v-brake. The lever
has two positions. One is less bad than the other, but
it still seems like too much grip strength is required.

Could there be (no pun intended) a leverage issue?
-----------------------------------------------------------
--
PeteCresswell

I've just finished setting up what was/is meant to be my winter bike, with a set of OLD Sachs drums. A helpful guy at this forum managed to supply me with the manuals, which strangely enough recommended the use of long stroke levers.
So I happily reused a pair of V-brake levers, with less than stellar results. Yesterday I switched them out for a set of BMX levers, with far less travel, which unfortunatelty only managed to change things from "appalling", to " bad".

The only thing right now that's keeping me from carrying the whole sorry mess out to the dumpster is that I'm telling myself that for a winter bike it's good not to be able to lock the brakes...
If I'm able to sorce one on the cheap I might try running a Travel Agent in reverse in an attempt to improve things.

Do note that all drums aren't created equal, and that there are several options available for the engineers to tailor the amount of travel required for decent performance.

 

[(PeteCresswell)]

Per dabac:
>So I happily reused a pair of V-brake levers, with less than stellar
>results. Yesterday I switched them out for a set of BMX levers, with far
>less travel, which unfortunatelty only managed to change things from
>"appalling", to " bad".

I think I've solved my own issue: Bigger lever.

I found the one surviving lever from when the bike was new:
http://tinyurl.com/2vaeom and stopping power went from
unacceptable to totally acceptable.
--
PeteCresswell

 

[[email protected]]

On Mar 2, 3:27 pm, "(PeteCresswell)" <[email protected]> wrote:
> Per dabac:
>
> >So I happily reused a pair of V-brake levers, with less than stellar
> >results. Yesterday I switched them out for a set of BMX levers, with far
> >less travel, which unfortunatelty only managed to change things from
> >"appalling", to " bad".
>
> I think I've solved my own issue: Bigger lever.
>
> I found the one surviving lever from when the bike was new:http://tinyurl.com/2vaeomand stopping power went from
> unacceptable to totally acceptable.
> --
> PeteCresswell

What is it about that lever that makes it suitable?

I'm considering the same hub, but I have no existing lever to fall
back on, so I need to select something new.

Joseph

 

[(PeteCresswell)]

Per [email protected]:
>What is it about that lever that makes it suitable?
>
>I'm considering the same hub, but I have no existing lever to fall
>back on, so I need to select something new.

Dunno exactly - might have more mechanical advantage. I tried
measuring cable travel vs lever throw on that one vs a v-brake
lever, but couldn't come up with a meaningful comparison in the
time allocated.

It might just be the larger/longer gripping surface.

If I were shopping, I'd look for one that's made for center-pull
brakes instead of v-brakes.
--
PeteCresswell

 

[(PeteCresswell)]

Per (PeteCresswell):
>If I were shopping, I'd look for one that's made for center-pull
>brakes instead of v-brakes.

I just eyeballed the levers on an old Schwinn "Mesa Runner" that
I rescued from the dumpster for parts - which has center-pull
brakes. http://tinyurl.com/28ugkr

Same relatively-massive lever size, same feel.

My take is that those levers are mechanically identical to and
would work the same as the one I have on there.
--
PeteCresswell

 

[Tom Sherman]

(PeteCresswell) wrote:
> Per (PeteCresswell):
>> If I were shopping, I'd look for one that's made for center-pull
>> brakes instead of v-brakes.
>
> I just eyeballed the levers on an old Schwinn "Mesa Runner" that
> I rescued from the dumpster for parts - which has center-pull
> brakes. http://tinyurl.com/28ugkr
>
> Same relatively-massive lever size, same feel.
>
> My take is that those levers are mechanically identical to and
> would work the same as the one I have on there.
>
Yes, one can not squeeze the modern "two-finger" ATB flat bar levers as
hard as the older levers designed for a full hand grip.

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

 

[Hank]

On Mar 2, 9:20 am, "[email protected]"
<[email protected]> wrote:
> On Mar 2, 3:27 pm, "(PeteCresswell)" <[email protected]> wrote:
>
> > Per dabac:
>
> > >So I happily reused a pair of V-brake levers, with less than stellar
> > >results. Yesterday I switched them out for a set of BMX levers, with far
> > >less travel, which unfortunatelty only managed to change things from
> > >"appalling", to " bad".
>
> > I think I've solved my own issue: Bigger lever.
>
> > I found the one surviving lever from when the bike was new:http://tinyurl.com/2vaeomandstopping power went from
> > unacceptable to totally acceptable.
> > --
> > PeteCresswell
>
> What is it about that lever that makes it suitable?
>
> I'm considering the same hub, but I have no existing lever to fall
> back on, so I need to select something new.
>
> Joseph

I'd look for ones marketed for flat-bar road bikes with sidepulls.
Like the Tektro RX 1.0 or Shimano BL-R440. They have the right
mechanical advantage, and 4-finger blades. Or you could get some Deore
XT BL-M730 or earlier off of ebay.

 

[Hank]

On Mar 2, 11:19 pm, Hank <[email protected]> wrote:
> On Mar 2, 9:20 am, "[email protected]"
>
>
>
>
>
> <[email protected]> wrote:
> > On Mar 2, 3:27 pm, "(PeteCresswell)" <[email protected]> wrote:
>
> > > Per dabac:
>
> > > >So I happily reused a pair of V-brake levers, with less than stellar
> > > >results. Yesterday I switched them out for a set of BMX levers, with far
> > > >less travel, which unfortunatelty only managed to change things from
> > > >"appalling", to " bad".
>
> > > I think I've solved my own issue: Bigger lever.
>
> > > I found the one surviving lever from when the bike was new:http://tinyurl.com/2vaeomandstoppingpower went from
> > > unacceptable to totally acceptable.
> > > --
> > > PeteCresswell
>
> > What is it about that lever that makes it suitable?
>
> > I'm considering the same hub, but I have no existing lever to fall
> > back on, so I need to select something new.
>
> > Joseph
>
> I'd look for ones marketed for flat-bar road bikes with sidepulls.
> Like the Tektro RX 1.0 or Shimano BL-R440. They have the right
> mechanical advantage, and 4-finger blades. Or you could get some Deore
> XT BL-M730 or earlier off of ebay.- Hide quoted text -
>
> - Show quoted text -

Just had a look on the Qbike.com price engine, and none of those
models seem to be available. However, the BL-R550 and BL-R770 are
available and have the same blade length and mechanical advantage.
Stupidly, but not surprisingly, they bill the 440, 550 and 770 models
as 8, 9, and 10-speed compatible, respectively. I hope that using the
wrong brake lever doesn't hurt my shifting.

 

[dabac]

.. I tried
measuring cable travel vs lever throw on that one vs a v-brake
lever, but couldn't come up with a meaningful comparison in the
time allocated...

An easy comparison is to measure the distance between the lever's pivot point and to where the cable attaches. For canti/caliper brakes it's typically 28 mm, and V-brake levers can run up to 45 mm or so.

 

[Werehatrack]

On Fri, 29 Feb 2008 21:58:53 -0500, "(PeteCresswell)" <[email protected]>
may have said:

>Now I'm wondering about the braking strength.

Bit late IMO. Better late than never in most cases.

>Understood that drum brakes aren't renowned for their braking
>power, but:
>-----------------------------------------------------------
>1) I have an image of a true metal drum with a couple of
> not-so-true brake shoes that need to wear in for awhile before
> they expose all of their surface to the drum.
>
> Any validity in this image?

Some...but it makes less difference than you might expect. Lining
material choices have more bearing on the friction produced than the
relative radius error.

>2) I've read that disc brakes need a certain amount of hard
> stopping to deposit something-or-other from the pads onto
> the discs to realize max performance.

Somebody didn't understand the subject very well. Some disc pads tend
to surface-harden as they break in; some do not. All pads will tend
to polish the rotor surface, a process which may or may not have much
of an effect on braking effort. A pad which leaves something on the
surface of the rotor is often a pad to avoid. (Yes, I'm aware of the
carbon-metallic pads and their graphite-like residue; I'm also aware
that the residue's effect is not particularly significant, and
removing it makes little or no difference.)

> Anything like that with drum brakes?

The friction surface needs to be and sound and uncontaminated as
possible. So, no, although the brake's performance may change as the
durm's inner surface gets polished by the shoes.

>3) I'm using the same lever I used for my v-brake. The lever
> has two positions. One is less bad than the other, but
> it still seems like too much grip strength is required.
>
> Could there be (no pun intended) a leverage issue?

The canti position is generally the one to use with most drum brakes,
from what I recall.

--
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