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Re: Al and suspension

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  • Dr. Michael Polsinelli
    I have an aluminum frame with front suspension. The front suspension is not ideal but it works. I can haul heavy loads. I dialed out as much play in the fork
    Message 1 of 14 , Nov 20, 2011
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      I have an aluminum frame with front suspension. The front suspension is
      not ideal but it works. I can haul heavy loads. I dialed out as much
      play in the fork as possible (it is still too much). If I can find a
      proper fork (1" threaded steerer) , I'll upgrade, but otherwise, I'm
      going to ride the frame into the ground before I replace it. I even have
      a chromoly rigid mtb that can be switched out, but it would take too
      much work and my current set up is too comfortable to mess with.

      Michael
    • TIM_H
      Found some Heavy Duty Monark Forks,question is what would it take to fit em? A great price too. Anyone know?
      Message 2 of 14 , Nov 20, 2011
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        Found some Heavy Duty Monark Forks,question is what would it take to fit em? A great price too.

        Anyone know?

        http://losangeles.craigslist.org/wst/bik/2708822029.html



        --- In rootsradicals@yahoogroups.com, "skeem2005" <emilyskopp@...> wrote:
        >
        > Why is front suspension bad for an Xtracycle? I understand rear suspension will not work.
        >
        > Is an Aluminum frame strong enough to withstand the torque of the Free Radical?
        >
      • Devian Gilbert
        fitting the fork to a frame depends on compatibility. 1. steer tube diameter 2. headset compatibility to frame and fork 3. Steer tube length vs headtube
        Message 3 of 14 , Nov 20, 2011
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          fitting the fork to a frame depends on compatibility.  
          1.  steer tube diameter
          2.  headset compatibility to frame and fork
          3.  Steer tube length vs headtube height, stack height, and stem.
          4.  Stem compatibility vs headset and steertube types and sizes.
          5.  finally handlebar... handlebar compatibility to stem.  clamping diameters of both steer tube and handlebar clamp.
          6.  geometry of frame and fork

          when I look at the Monark fork, my first impression is that it is not an optimal candidate for a cargo bike.  However, lets say this fork was already on a cruiser type of bicycle and that bike could be a decent cargo bike.

          if a person were to take a modern MTB and try to put that fork on it, and convert it to a cargo bike... I don't think it would be the best idea.



          On Nov 20, 2011, at 11:26 AM, TIM_H wrote:

           



          Found some Heavy Duty Monark Forks,question is what would it take to fit em? A great price too.

          Anyone know?

          http://losangeles.craigslist.org/wst/bik/2708822029.html

          --- In rootsradicals@yahoogroups.com, "skeem2005" <emilyskopp@...> wrote:
          >
          > Why is front suspension bad for an Xtracycle? I understand rear suspension will not work.
          >
          > Is an Aluminum frame strong enough to withstand the torque of the Free Radical?
          >


        • TIM_H
          Thanks for that Devian.So it appears there isnt a simple plug n play fork huh.Thats to bad. I was thinking to myself I wonder if any Pedicabs use suspension
          Message 4 of 14 , Nov 20, 2011
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            Thanks for that Devian.So it appears there isnt a simple plug n play fork huh.Thats to bad.

            I was thinking to myself I wonder if any Pedicabs use suspension forks.I did a quick search and found some use heavy duty triple-clamp forks on their bicycles.I assume their not plug n play either?

            --- In rootsradicals@yahoogroups.com, Devian Gilbert <asanacycles@...> wrote:
            >
            > fitting the fork to a frame depends on compatibility.
            > 1. steer tube diameter
            > 2. headset compatibility to frame and fork
            > 3. Steer tube length vs headtube height, stack height, and stem.
            > 4. Stem compatibility vs headset and steertube types and sizes.
            > 5. finally handlebar... handlebar compatibility to stem. clamping diameters of both steer tube and handlebar clamp.
            > 6. geometry of frame and fork
            >
            > when I look at the Monark fork, my first impression is that it is not an optimal candidate for a cargo bike. However, lets say this fork was already on a cruiser type of bicycle and that bike could be a decent cargo bike.
            >
            > if a person were to take a modern MTB and try to put that fork on it, and convert it to a cargo bike... I don't think it would be the best idea.
            >
            >
            >
            > On Nov 20, 2011, at 11:26 AM, TIM_H wrote:
            >
            > >
            > >
            > > Found some Heavy Duty Monark Forks,question is what would it take to fit em? A great price too.
            > >
            > > Anyone know?
            > >
            > > http://losangeles.craigslist.org/wst/bik/2708822029.html
            > >
            > > --- In rootsradicals@yahoogroups.com, "skeem2005" <emilyskopp@> wrote:
            > > >
            > > > Why is front suspension bad for an Xtracycle? I understand rear suspension will not work.
            > > >
            > > > Is an Aluminum frame strong enough to withstand the torque of the Free Radical?
            > > >
            > >
            > >
            >
          • Devian Gilbert
            the bicycle industry is notorious for lack of linear standards its not like going to the autoparts store and asking for an automotive part for a certain make,
            Message 5 of 14 , Nov 20, 2011
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              the bicycle industry is notorious for lack of linear standards
              its not like going to the autoparts store and asking for an automotive part for a certain make, model and year of vehicle.

              as with most bicycle projects, an direct method is to simply start out with a parts list and try to accurately spec a project.

              what do you have in mind?

              d-
              On Nov 20, 2011, at 12:30 PM, TIM_H wrote:

               



              Thanks for that Devian.So it appears there isnt a simple plug n play fork huh.Thats to bad.

              I was thinking to myself I wonder if any Pedicabs use suspension forks.I did a quick search and found some use heavy duty triple-clamp forks on their bicycles.I assume their not plug n play either?

              --- In rootsradicals@yahoogroups.com, Devian Gilbert <asanacycles@...> wrote:
              >
              > fitting the fork to a frame depends on compatibility.
              > 1. steer tube diameter
              > 2. headset compatibility to frame and fork
              > 3. Steer tube length vs headtube height, stack height, and stem.
              > 4. Stem compatibility vs headset and steertube types and sizes.
              > 5. finally handlebar... handlebar compatibility to stem. clamping diameters of both steer tube and handlebar clamp.
              > 6. geometry of frame and fork
              >
              > when I look at the Monark fork, my first impression is that it is not an optimal candidate for a cargo bike. However, lets say this fork was already on a cruiser type of bicycle and that bike could be a decent cargo bike.
              >
              > if a person were to take a modern MTB and try to put that fork on it, and convert it to a cargo bike... I don't think it would be the best idea.
              >
              >
              >
              > On Nov 20, 2011, at 11:26 AM, TIM_H wrote:
              >
              > >
              > >
              > > Found some Heavy Duty Monark Forks,question is what would it take to fit em? A great price too.
              > >
              > > Anyone know?
              > >
              > > http://losangeles.craigslist.org/wst/bik/2708822029.html
              > >
              > > --- In rootsradicals@yahoogroups.com, "skeem2005" <emilyskopp@> wrote:
              > > >
              > > > Why is front suspension bad for an Xtracycle? I understand rear suspension will not work.
              > > >
              > > > Is an Aluminum frame strong enough to withstand the torque of the Free Radical?
              > > >
              > >
              > >
              >


            • Tone
              Enough people have spoken about the reason why front suspension is not ideal on an Xtracycle, so I will not address it. However, I will speak about aluminum
              Message 6 of 14 , Nov 21, 2011
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                Enough people have spoken about the reason why front suspension is not
                ideal on an Xtracycle, so I will not address it. However, I will speak
                about aluminum frames.

                At the moment I have a steel single-framed Surly Big Dummy, which I have
                had for a couple of years. However, for several years before I “upgraded”
                to a Big Dummy, I had a few Xtracycle FreeRadical extensions on my
                Univega 750 FS aluminum frame. I really felt that my old Univega with the
                long tail extension was a stiffer ride than my Big Dummy. There have been
                some old discussions about steel versus aluminum on RootsRadicals, so you
                can search the archives from a couple of years ago to possibly find them.
                Basically though, steel has some flex in it, but aluminum does not, which
                is why I think I believe my old Univega had less flexx while loaded.
                Understand though, while aluminum is lighter than steel and not as prone
                to rust, it is not as easy to fix a break by welding. Once the aluminum
                hits beyond its maximum weight/pressure/etc. limit it will break
                catastrophically, but a steel frame is more likely just to bend slightly
                and can also likely be bent back without too much concern.

                In one of the responses someone stated they had cracked two aluminum
                frames when fitted with a FreeRadical. They also said they carried lots
                of weight and even jumped off curbs. I have no idea how thick that
                person’s aluminum frames were, but in my case the Univega 750 FS frame I
                had was extremely thick. Here is a link to a photo where you can see the
                thickness of the frame:
                http://www.cranksgiving.net/XtraLoads/LunarLoad-Angle.jpg
                Only the seat post had what would be considered normally sized tubing.
                Even the chain-stays seemed extra thick compared to other steel and
                aluminum bikes. In fact when I got the Univega I was already working as a
                bike messenger in NYC and I had broken a chrome-moly frame while on the
                job. It was the bike mechanic at my local shop, who actually picked out
                the Univega for me because he knew exactly what kind of treatment I put
                my bike through... and that was even a few years before I got an
                Xtracycle. Even later after I became an Xtracycle rider, I ended up
                breaking three FreeRadical extensions on the Univega before “upgrading”
                to a Big Dummy.
                I would not recommend ever hauling a load like the one in the photo, but
                obviously it shows just how strong the aluminum frame was. Also in the
                photo you can see that I lock up my bike with a 3’ long 15 pound
                Kryptonite chain. Working as a full time messenger meant I was locking
                and unlocking my bike at least 20 times a day, which is why the paint job
                got scratched and chipped off so much. That chain must have undoubtedly
                worn into the frame as well. I will say I tried never to jump off curbs
                that much, especially when loaded... after all I avoided riding on
                sidewalks as much as possible. In any case, not performing hops or drops
                on my bike certainly gave the aluminum frame a longer life, but I
                definitely had my share of collisions. When you are riding a bicycle on
                NYC streets several hours a day for several years it is statistically
                unavoidable.
                Still my Univega-Xtracycle survived all the way until at least a year
                into living in York, PA, where I commuted by bike about ten miles round
                trip each day to and from my non-cycling job in almost all weather
                conditions. Eventually though it did break down after numerous bulky and
                heavy loads with over 30,000 miles on it. I am not sure that many bike
                frames, even steel ones, can say the same. So when I “upgraded” to a
                single-framed steel big dummy I was surprised by how it flexed more when
                loaded, not to mention it weighed 10-15 more pounds compared to my
                Univega.

                In case you are wondering, when my aluminum Univega did break down it
                seemed to literally tear apart at the lower weld right behind the head
                tube. It tore almost completely through the down tube from the under-side
                up. When it finally happened I was commuting to work up a slight hill
                without any real load and my ride quickly built up a severe wobble. I
                thought I had a flat in the front wheel or something, but before I could
                even get both feet on the ground the front wheel rolled out ahead as the
                bottom bracket and chain rings contacted pavement. I just snapped the
                rest apart with a little brute bending force from my hands.
                The winter before there had been a day with snow where I was riding to
                work and I rear-ended a car. There was low visibility through my slightly
                fogged up ski-goggles because of the snow, but the driver’s rear lights
                did not come on to indicate he had stopped, only his running lights had
                remained lit. When I finally did realize the car in front of me had
                stopped, I broke as hard as I could on my disc brakes, but the momentum
                slid me in over the wet asphalt. It did not feel like a hard impact, but
                it was enough to bend my front fork back so my wheel touched the down
                tube. The car in front had snow on the back window and if the driver did
                feel the bump he most likely did not see anyone behind him in his side
                view mirrors. Considering the awful weather the driver did not even step
                out of the vehicle and instead just drove off a few seconds after the
                collision. The car had not sustained any damage because only my front
                tire had contacted their rear bumper. My 1.5” higher-pressure semi-slick
                tires were still fully inflated. I had to call my wife to drive me to
                work in our minivan. Regardless, in retrospect I am pretty sure that bump
                must have contributed significantly to the eventual frame breakage
                several months later.

                I guess in conclusion, you can certainly use an aluminum frame as your
                Xtracycle donor bike… but just make sure the frame has really thick
                tubing, avoid curb hopping & dropping, and do not rear-end massive static
                objects with your front wheel. Ride safe,
                _TONE_
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