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-   -   Rear Bakfiets? (http://www.bikeforums.net/alt-bike-culture/626122-rear-bakfiets.html)

Leo H. 03-04-10 09:14 PM

Rear Bakfiets?
 
Ok, I've checked out Tom's Cargo Bikes page and have looked at Bilenkys, Madsens and Bullitts, but as I was trying to sketch out how I was going to build a cargo bike with a fabricatin' friend, I asked him, 'why not build the platform towards the back?' Put the 20" wheel at the back a la Madsen and use a single or dual front sprocket to keep the chain lower, and fabricate the platform above the chainline. Possibly use an internal geared hub and a small single sprocket to lower the chain.

I am just thinking out loud, so I'm curious as to what the collective fabricating brain says to this?

There must be some sort of obvious reason why not, I'm just blueskying here. Has someone ever even tried to construct a sled in this configuration?

Thanks,

Leo H.
Sun Valley, NV

deathshadow60 03-05-10 07:39 AM

Well, I'm partial to internal gear hubs, so that's the route I'd be looking at. Sure there's some mechanical loss of energy, but that's offset by reliability, low maintenance, less **** to clean, and getting rid of this whole 'jumping a chain from gear to gear in the air' nonsense.

Much less that we're not stuck with the mediocre Sturmey-Archer's anymore. The Shimano 7 and 9 speed models are really nice and much better quality than the older ones. A lot of times you can pick up barely used Shimano 3's off e-fence sold by people who upped to more gearing options, which would keep the price down (if you're up to doing some wheelbuilding).

You MIGHT also want to look into shaft drive to further simplify and/or make room for your cargo area, though that increases price dramatically - especially since as you move the tire back you'd need a custom shaft built, while making a longer chain and wrapping it with strategically placed sprockets around your cargo bay should be easy-peasy.

Guess it really depends on your budget - all the one's at Tom's look to be ghetto hacks/donate builds. If doing it on the cheap extending the front seems the way to go as it would be a LOT simpler/cheaper to implement as all you have to deal with is steering, especially since most (but not all) of them appear to even skip having a front brake.

Having it in front of you might also have a riding advantage - you can SEE when you're leaning enough in a turn you might clip the ground. With it behind you it's possible to forget. Buddy of mine mounted some hardshell motorcycle saddlebags on his bicycle once, took a corner, clipped one and went flying right over his handlebars. Something to keep in mind - it's easy to forget clearance when it's behind you.

Artkansas 03-05-10 09:11 AM

I'm guessing that the chain is the reason that the bakfiets style bikes put the cargo in the front and not the back. Most cargo carrying bikes that carry the cargo in the rear seem to be more like the Xtra Cycle or Big Dummy and split the cargo area into two.

I suppose you could be really radical and make it like a Cruzbike with the drive train in the front, giving you complete leeway in the back for cargo.

Have you checked in the frame building and utility bike forums?

purplepeople 03-05-10 09:31 AM

Look up the Freight 8 by Mike Burrows. It uses an idler to keep the chain under the cargo tub. Much simpler than running a steering link to the front. Safer too if you take into account the fact that many riders simply do not understand mechanics well enough to examine steering linkages for wear or damage.

If I were your frame builder, I would ask one question.... what are you carrying? Of course, this is a complex question and the answer will involve physical size and weight, but that can easily determine the layout of your machine.

If you are looking for a generalized cargo bike, then your simplest solution is still the Xtracycle and the cheapest (complete bike) may be a Yuba Mundo or Kona Ute. If you are willing to hack a little, you can get a cheap Walmart tandem, remove the rear seat and add cargo to either side.

If you are looking at making a frame yourself, bear in mind that any cargo system like the bakfiets or the Freight requires very large beams underneath. Compare this to a longtail, which is really just a tandem frame with an extra large rack.

The simplest way of extending a mountain bike frame is to cut the stays behind the seat post and behind the bottom bracket. Use a 1x2 tube to extend the chainstays and a girder system to build the rack and connect the seat stays at the same time.

:)ensen.

squirtdad 03-05-10 10:46 AM

Based on commensts in utility forum, and observations on the street, the baksfiet was not really designed as a cargo bike, but as a utility bike. On of the most common things I have seen, both in person (there are 3 or 4 in my neighborhood) and in picturres is that often the box (baks) is used to carry small kids....and having them upfront where you can see them is a benefit.

check out the utility forum also

have fun

StephenH 03-05-10 12:17 PM

One disadvantage is getting the load up higher. But on a tricycle, that's not as much of an issue, so you see all kinds of adult trikes, pedicabs, and cargo trikes built on a pedicab frame that are available. The kids-in-front is something else that came to mind for me as well.

squirtdad 03-05-10 12:54 PM

not directly related to rear question but a guy is selling a a home made long john...shows what is possible...you could reverse the design to a degree and have the cargo in the back

http://sfbay.craigslist.org/sby/bik/1626950824.html

Leo H. 03-06-10 09:48 PM

re: 8 freight
 
Thank you very much for pointing me to that design! While we were sitting there sketching out pieces and looking at images of various front cargo bikes, I just started wondering about putting the platform in the back and thinking that it appeared that it could be simpler in construction, aside from routing the chain, to do it that way. Even though I didn't think I'd come up with an original design, I feel good seeing that my idea has been built successfully.

As for what I plan to use it for, carrying two smallish dogs and as a grocery getter. I like the idea of the upper frame 'round the cargo platform supporting a fabric/canvas bag. That'd be perfect for containing the dogs, yet allowing them while harnessed, to rest their paws on the frame and viewing around them.

Fitting the platform in and connecting it to the bb and the rear axle just seems a simpler construction than all the front cutting and refitting and the steering adjustments.


Leo H.
Sun Valley, NV

Leo H. 03-06-10 09:50 PM

Quote:

Originally Posted by squirtdad (Post 10484762)
Based on commensts in utility forum, and observations on the street, the baksfiet was not really designed as a cargo bike, but as a utility bike. On of the most common things I have seen, both in person (there are 3 or 4 in my neighborhood) and in picturres is that often the box (baks) is used to carry small kids....and having them upfront where you can see them is a benefit.

check out the utility forum also

have fun



Thanks, I'll look in the utility forum as well.


Leo H.
Sun Valley, NV

Leo H. 03-06-10 10:12 PM

Quote:

Originally Posted by Artkansas (Post 10484324)
I'm guessing that the chain is the reason that the bakfiets style bikes put the cargo in the front and not the back. Most cargo carrying bikes that carry the cargo in the rear seem to be more like the Xtra Cycle or Big Dummy and split the cargo area into two.

I suppose you could be really radical and make it like a Cruzbike with the drive train in the front, giving you complete leeway in the back for cargo.

Have you checked in the frame building and utility bike forums?

I haven't checked the frame building forum, thanks for the pointer. I don't know about the fwd, that seems a bit out of my building comfort zone, but it's an interesting thought...a recumbent cargo bike.

Leo H.
Sun Valley, NV

Leo H. 03-06-10 10:44 PM

re: fwd c/b
 
Quote:

Originally Posted by Artkansas (Post 10484324)
I'm guessing that the chain is the reason that the bakfiets style bikes put the cargo in the front and not the back. Most cargo carrying bikes that carry the cargo in the rear seem to be more like the Xtra Cycle or Big Dummy and split the cargo area into two.

I suppose you could be really radical and make it like a Cruzbike with the drive train in the front, giving you complete leeway in the back for cargo.

Have you checked in the frame building and utility bike forums?

As I think about it, an fwd would probably put too much weight towards the front of the design, unless it was fully loaded.

Need too much money and spare time to work that one out in real life....


Leo H.
Sun Valley, NV


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