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Re: [Geared_hub_bikes] Drum Brake Question

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  • Mike Bullis
    Just from personal experience, I d say myth. I ve run front drums for over twenty years and have yet to have a problem. Mike ... From: Rich
    Message 1 of 17 , May 27, 2010
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      Just from personal experience, I'd say myth. I've run front drums for over twenty years and have yet to have a problem.

      Mike

      --- On Thu, 5/27/10, Rich <astronut1001@...> wrote:

      From: Rich <astronut1001@...>
      Subject: [Geared_hub_bikes] Drum Brake Question
      To: Geared_hub_bikes@yahoogroups.com
      Date: Thursday, May 27, 2010, 3:07 PM

       

      It has been my understanding that it is poor practice to fit a drum front brake to a fork not designed for it. This is due to the lower part of standard front forks not being designed to take the braking force and rotational torque that it is subjected to by a drum brake. These are supposedly much greater than the forces the lower end of the fork blades is subjected to by a caliper or cantilever brake.

      Is there any truth to this or is it a popular myth?

      Rich Wood


    • Joe Bunik
      I can t substantiate this, but do recall reading a marked difference exists in force transferred to the blades in drum vs. disc braking. The primary purpose
      Message 2 of 17 , May 27, 2010
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        I can't substantiate this, but do recall reading a marked difference
        exists in force transferred to the blades in drum vs. disc braking.
        The primary purpose for the torque arm on a drum brake, iirc, is to
        "restrain" the hub from wind-up.

        How/where this departs from the "grabbing" required of disk braking, I
        am not fully versed - but, I would also assume that the length of the
        (drum) torque arm would be an additional factor to consider here.

        =- Joe Bunik
        Walnut Creek, CA

        On 5/27/10, Mike Bullis <workinonitstill@...> wrote:
        > Just from personal experience, I'd say myth. I've run front drums for over
        > twenty years and have yet to have a problem.
        >
        > Mike
        >
        > --- On Thu, 5/27/10, Rich <astronut1001@...> wrote:
        >
        > From: Rich <astronut1001@...>
        > Subject: [Geared_hub_bikes] Drum Brake Question
        > To: Geared_hub_bikes@yahoogroups.com
        > Date: Thursday, May 27, 2010, 3:07 PM
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        > front brake to a fork not designed for it. This is due to the lower part of
        > standard front forks not being designed to take the braking force and
        > rotational torque that it is subjected to by a drum brake. These are
        > supposedly much greater than the forces the lower end of the fork blades is
        > subjected to by a caliper or cantilever brake.
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        > Is there any truth to this or is it a popular myth?
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        > Rich Wood
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      • PDX Randonneur
        In addition, have any drum brake users, specifically Sturmey drum brakes, used road levers and / or cross levers with them? -- R.R.
        Message 3 of 17 , May 27, 2010
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          In addition, have any drum brake users, specifically Sturmey drum
          brakes, used road levers and / or cross levers with them?



          --
          R.R.



          On Thu, May 27, 2010 at 1:07 PM, Rich <astronut1001@...> wrote:
          > It has been my understanding that it is poor practice to fit a drum front brake to a fork not designed for it.  This is due to the lower part of standard front forks not being designed to take the braking force and rotational torque that it is subjected to by a drum brake.  These are supposedly much greater than the forces the lower end of the fork blades is subjected to by a caliper or cantilever brake.
          >
          > Is there any truth to this or is it a popular myth?
          >
          > Rich Wood
          >
          >
          >
          > ------------------------------------
          >
          > Yahoo! Groups Links
          >
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          >
        • Mike Bullis
          I run SA Elites on my brevet bike with road levers. Mike ... From: PDX Randonneur Sent: Thursday, May 27, 2010 5:15 PM To:
          Message 4 of 17 , May 27, 2010
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            I run SA Elites on my brevet bike with road levers.

            Mike



            From: PDX Randonneur <pdxrandonneur@...>
            Sent: Thursday, May 27, 2010 5:15 PM
            To: Geared_hub_bikes@yahoogroups.com
            Subject: Re: [Geared_hub_bikes] Drum Brake Question

             

            In addition, have any drum brake users, specifically Sturmey drum
            brakes, used road levers and / or cross levers with them?

            --
            R.R.

            On Thu, May 27, 2010 at 1:07 PM, Rich <astronut1001@...> wrote:
            > It has been my understanding that it is poor practice to fit a drum front brake to a fork not designed for it.  This is due to the lower part of standard front forks not being designed to take the braking force and rotational torque that it is subjected to by a drum brake.  These are supposedly much greater than the forces the lower end of the fork blades is subjected to by a caliper or cantilever brake.
            >
            > Is there any truth to this or is it a popular myth?
            >
            > Rich Wood
            >
            >
            >
            > ------------------------------------
            >
            > Yahoo! Groups Links
            >
            >
            >
            >



            [The entire original message is not included]
          • Rich
            Joe; Welcome to the group. Front disc brakes with the caliper mounted behind the fork stanchion tube, as is typical, tend to pull the wheel down out of the
            Message 5 of 17 , May 27, 2010
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              Joe;

              Welcome to the group.

              Front disc brakes with the caliper mounted behind the fork stanchion tube, as is typical, tend to pull the wheel down out of the dropouts under braking. I ran across a web site which discussed this in considerable detail some time back. In this case "lawyers lips" may be worthwhile.

              A drum brake with the torque arm ahead of the fork stanchion tube should tend to force the axle into the dropout under braking. So will a disc brake if the caliper is mounted in front of the fork tube but that is not the usual mounting.

              I was thinking more of the forces on the fork being different when using caliper or other rim brakes versus drum or disc brakes.

              Rich Wood


              --- In Geared_hub_bikes@yahoogroups.com, Joe Bunik <jbunik@...> wrote:
              >
              > I can't substantiate this, but do recall reading a marked difference
              > exists in force transferred to the blades in drum vs. disc braking.
              > The primary purpose for the torque arm on a drum brake, iirc, is to
              > "restrain" the hub from wind-up.
              >
              > How/where this departs from the "grabbing" required of disk braking, I
              > am not fully versed - but, I would also assume that the length of the
              > (drum) torque arm would be an additional factor to consider here.
              >
              > =- Joe Bunik
              > Walnut Creek, CA
              >
              > On 5/27/10, Mike Bullis <workinonitstill@...> wrote:
              > > Just from personal experience, I'd say myth. I've run front drums for over
              > > twenty years and have yet to have a problem.
              > >
              > > Mike
              > >
              > > --- On Thu, 5/27/10, Rich <astronut1001@...> wrote:
              > >
              > > From: Rich <astronut1001@...>
              > > Subject: [Geared_hub_bikes] Drum Brake Question
              > > To: Geared_hub_bikes@yahoogroups.com
              > > Date: Thursday, May 27, 2010, 3:07 PM
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              > > It has been my understanding that it is poor practice to fit a drum
              > > front brake to a fork not designed for it. This is due to the lower part of
              > > standard front forks not being designed to take the braking force and
              > > rotational torque that it is subjected to by a drum brake. These are
              > > supposedly much greater than the forces the lower end of the fork blades is
              > > subjected to by a caliper or cantilever brake.
              > >
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              > > Is there any truth to this or is it a popular myth?
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              > > Rich Wood
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            • Rich
              For those who might be interested here is a link to the web page that discusses the potential problem of disc brakes causing the front wheel to be pulled out
              Message 6 of 17 , May 27, 2010
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                For those who might be interested here is a link to the web page that discusses the potential problem of disc brakes causing the front wheel to be pulled out of fork dropouts.

                http://www.ne.jp/asahi/julesandjames/home/disk_and_quick_release/

                I found it interesting.

                Rich Wood

                --- In Geared_hub_bikes@yahoogroups.com, "Rich" <astronut1001@...> wrote:
                >
                > Joe;
                >
                > Welcome to the group.
                >
                > Front disc brakes with the caliper mounted behind the fork stanchion tube, as is typical, tend to pull the wheel down out of the dropouts under braking. I ran across a web site which discussed this in considerable detail some time back. In this case "lawyers lips" may be worthwhile.
                >
                > A drum brake with the torque arm ahead of the fork stanchion tube should tend to force the axle into the dropout under braking. So will a disc brake if the caliper is mounted in front of the fork tube but that is not the usual mounting.
                >
                > I was thinking more of the forces on the fork being different when using caliper or other rim brakes versus drum or disc brakes.
                >
                > Rich Wood
                >
                >
                > --- In Geared_hub_bikes@yahoogroups.com, Joe Bunik <jbunik@> wrote:
                > >
                > > I can't substantiate this, but do recall reading a marked difference
                > > exists in force transferred to the blades in drum vs. disc braking.
                > > The primary purpose for the torque arm on a drum brake, iirc, is to
                > > "restrain" the hub from wind-up.
                > >
                > > How/where this departs from the "grabbing" required of disk braking, I
                > > am not fully versed - but, I would also assume that the length of the
                > > (drum) torque arm would be an additional factor to consider here.
                > >
                > > =- Joe Bunik
                > > Walnut Creek, CA
                > >
                > > On 5/27/10, Mike Bullis <workinonitstill@> wrote:
                > > > Just from personal experience, I'd say myth. I've run front drums for over
                > > > twenty years and have yet to have a problem.
                > > >
                > > > Mike
                > > >
                > > > --- On Thu, 5/27/10, Rich <astronut1001@> wrote:
                > > >
                > > > From: Rich <astronut1001@>
                > > > Subject: [Geared_hub_bikes] Drum Brake Question
                > > > To: Geared_hub_bikes@yahoogroups.com
                > > > Date: Thursday, May 27, 2010, 3:07 PM
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                > > > It has been my understanding that it is poor practice to fit a drum
                > > > front brake to a fork not designed for it. This is due to the lower part of
                > > > standard front forks not being designed to take the braking force and
                > > > rotational torque that it is subjected to by a drum brake. These are
                > > > supposedly much greater than the forces the lower end of the fork blades is
                > > > subjected to by a caliper or cantilever brake.
                > > >
                > > >
                > > >
                > > > Is there any truth to this or is it a popular myth?
                > > >
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                > > > Rich Wood
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              • Mike Wilson
                I bent a fork with a drum brake but that was due to improper cable routing. I ran the cable like a centerpull brake. Bad idea. I have used Weinmann dropped
                Message 7 of 17 , May 28, 2010
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                  I bent a fork with a drum brake but that was due to improper cable routing. I ran the cable like a centerpull brake. Bad idea.

                  I have used Weinmann dropped bar brake levers with Sturmey Archer drum brakes and it did not work - not enough cable pull. The bike was not interesting enough to solve the problem. Potential solutions were Mafac brake levers, or a travel agent or Jtek pulley.


                  Michael Wilson
                • Mike Wilson
                  Another potential dropped bar brake lever for a Sturmey Archer drum brake is the Dia Compe 287V which is designed for v-brakes. No I have not tested that idea.
                  Message 8 of 17 , May 29, 2010
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                    Another potential dropped bar brake lever for a Sturmey Archer drum brake is the Dia Compe 287V which is designed for v-brakes.

                    No I have not tested that idea.

                    Michael Wilson
                  • Simon Boddy
                    This has recently been discussed over on the moulton list. Contrary to the above, Dan Farrell, who s knowledge is hard to fault, says categorically that drums
                    Message 9 of 17 , May 29, 2010
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                      This has recently been discussed over on the moulton list. Contrary to the above, Dan Farrell, who's knowledge is hard to fault, says categorically that drums take 1:1, old style brake levers, not V-brake levers. I'm personally running a sturmey drum on the rear, against a campag ergo road shifter, and this setup works very well. If cable pull was an issue, I would expect it to be difficult to adjust the brake to avoid rubbing. This is not the case. I have great, all weather braking, good power and modulation. I'd put the drum on the front, but the moulton front forks, I'm told, aren't up to it.

                      regards Simon

                      On Sat, May 29, 2010 at 2:06 PM, Mike Wilson <mwilson@...> wrote:
                       

                      Another potential dropped bar brake lever for a Sturmey Archer drum brake is the Dia Compe 287V which is designed for v-brakes.

                      No I have not tested that idea.

                      Michael Wilson


                    • Mike Wilson
                      This has recently been discussed over on the moulton list. Contrary to the above, Dan Farrell, who s knowledge is hard to fault, says categorically that drums
                      Message 10 of 17 , May 30, 2010
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                        This has recently been discussed over on the moulton list. Contrary to the
                        above, Dan Farrell, who's knowledge is hard to fault, says categorically
                        that drums take 1:1, old style brake levers, not V-brake levers. I'm
                        personally running a sturmey drum on the rear, against a campag ergo road
                        shifter, and this setup works very well. If cable pull was an issue, I would
                        expect it to be difficult to adjust the brake to avoid rubbing. This is not
                        the case. I have great, all weather braking, good power and modulation. I'd
                        put the drum on the front, but the moulton front forks, I'm told, aren't up
                        to it.

                        regards Simon
                        ---------------
                        That is not my experience, but I would not be surprised to learn that some S.A. drum brakes work differently than others. I could not find a cable adjustment that would both give effective rear braking and no rubbing with the lever at idle. This with a 5 speed drum brake I believe from the 1990s.

                        Michael Wilson
                      • Rich
                        Per a recent post on BF SRAM drum brakes want a lever that pulls 16mm of cable and has a pull ratio minimum of 3.6:1. I recently measured several road levers,
                        Message 11 of 17 , May 30, 2010
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                          Per a recent post on BF SRAM drum brakes want a lever that pulls 16mm of cable and has a pull ratio minimum of 3.6:1. I recently measured several road levers, mounted on a set of drop bars, and got measured cable pulls of 13mm on them so it seems to be pretty standard pull for current road levers. Pull ratios are all about 4:1 on the current levers so they meet the SRAM suggested mimimum for pull ratio.

                          The V brake drop levers have pull ratios of 2.3 (Tektro) to 2.7 (Dia Compe) to 1. They pull lots of cable but with the pull ratios would likely require a very hard pull to work with a drum brake for maximum retardation.

                          Rich Wood

                          Rich Wood

                          --- In Geared_hub_bikes@yahoogroups.com, Mike Wilson <mwilson@...> wrote:
                          >
                          > This has recently been discussed over on the moulton list. Contrary to the
                          > above, Dan Farrell, who's knowledge is hard to fault, says categorically
                          > that drums take 1:1, old style brake levers, not V-brake levers. I'm
                          > personally running a sturmey drum on the rear, against a campag ergo road
                          > shifter, and this setup works very well. If cable pull was an issue, I would
                          > expect it to be difficult to adjust the brake to avoid rubbing. This is not
                          > the case. I have great, all weather braking, good power and modulation. I'd
                          > put the drum on the front, but the moulton front forks, I'm told, aren't up
                          > to it.
                          >
                          > regards Simon
                          > ---------------
                          > That is not my experience, but I would not be surprised to learn that some S.A. drum brakes work differently than others. I could not find a cable adjustment that would both give effective rear braking and no rubbing with the lever at idle. This with a 5 speed drum brake I believe from the 1990s.
                          >
                          > Michael Wilson
                          >
                        • prester_john_in_cathay
                          Sturmey began offering drum brakes somewhat before V-brakes and their levers appeared on the market.
                          Message 12 of 17 , May 30, 2010
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                            Sturmey began offering drum brakes somewhat before V-brakes and their levers appeared on the market.

                            <http://www.sturmey-archerheritage.com/index.php?page=history-detail&id=26>

                            PJ
                          • Rich
                            Agreed, like at least 70+ years before V-brakes ;-) I have never looked over or tested older brake levers to even have an idea of what their cable pull or pull
                            Message 13 of 17 , May 30, 2010
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                              Agreed, like at least 70+ years before V-brakes ;-)

                              I have never looked over or tested older brake levers to even have an idea of what their cable pull or pull ratio typically was. My oldest are some 1980s Campy drilled blade Super Record levers.

                              Rich Wood

                              --- In Geared_hub_bikes@yahoogroups.com, "prester_john_in_cathay" <prester_john_in_cathay@...> wrote:
                              >
                              > Sturmey began offering drum brakes somewhat before V-brakes and their levers appeared on the market.
                              >
                              > <http://www.sturmey-archerheritage.com/index.php?page=history-detail&id=26>
                              >
                              > PJ
                              >
                            • Alex Wetmore
                              From: Mike Wilson [mwilson@juniper.net] ... I agree with Simon and have found that most drum brakes want cantilever lever pull, not V-brake pull. In fact the
                              Message 14 of 17 , May 31, 2010
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                                From: Mike Wilson [mwilson@...]
                                > That is not my experience, but I would not be surprised to learn that
                                > some S.A. drum brakes work differently than others. I could not find a
                                > cable adjustment that would both give effective rear braking and no
                                > rubbing with the lever at idle. This with a 5 speed drum brake I believe
                                > from the 1990s.

                                I agree with Simon and have found that most drum brakes want cantilever lever pull, not V-brake pull. In fact the worst drum brakes that I've used have all been because they've been setup with V-brake levers.

                                When you used that drum brake was it with drop bar levers or flat bar levers? Drop bar levers (especially aero ones) don't pull quite as much cable, which can cause problems.

                                V-brakes didn't come out until the mid-90s, so it is pretty unlikely that you'd find a drum brake made then which required V-brake levers.

                                alex
                              • PDX Randonneur
                                I asked the Sturmey Archer guy on the Sturmey facebook page and this is his answer: Road levers I have never tried but we recommend standard cantilever style
                                Message 15 of 17 , Jun 1 12:26 PM
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                                  I asked the Sturmey Archer guy on the Sturmey facebook page and this
                                  is his answer:

                                  "Road levers I have never tried but we recommend standard cantilever
                                  style brake levers. The longer the brake lever the better the brakes
                                  will feel."

                                  http://www.facebook.com/topic.php?uid=102085133940&topic=15586

                                  --
                                  R.R.


                                  On Mon, May 31, 2010 at 8:02 AM, Alex Wetmore <alex@...> wrote:
                                  > From: Mike Wilson [mwilson@...]
                                  >> That is not my experience, but I would not be surprised to learn that
                                  >> some S.A. drum brakes work differently than others.  I could not find a
                                  >> cable adjustment that would both give effective rear braking and no
                                  >> rubbing with the lever at idle.  This with a 5 speed drum brake I believe
                                  >> from the 1990s.
                                  >
                                  > I agree with Simon and have found that most drum brakes want cantilever lever pull, not V-brake pull.  In fact the worst drum brakes that I've used have all been because they've been setup with V-brake levers.
                                  >
                                  > When you used that drum brake was it with drop bar levers or flat bar levers?  Drop bar levers (especially aero ones) don't pull quite as much cable, which can cause problems.
                                  >
                                  > V-brakes didn't come out until the mid-90s, so it is pretty unlikely that you'd find a drum brake made then which required V-brake levers.
                                  >
                                  > alex
                                  >
                                  > ------------------------------------
                                  >
                                  > Yahoo! Groups Links
                                  >
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