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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
      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 2 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 3 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 4 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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