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Old 10-16-10, 02:39 PM   #1
werks
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My new take-apart bike

I'm not sure this belongs on a folding bike forum, but here goes .....

I've been wanting to transport a workout bike in the trunk of my Porsche vs using a trunk mounted rack, so this solution is the simplest I could come up with.

I purchased a sacrificial lamb .... Specialized Rock Hopper for $30.00, used my high-tech hacksaw to cut through the top and downtubes, and made sleeves from 1 3/8" 6061-T6 aluminum tubing. Total cost to convert the Rock Hopper to take-apart duty was about $5.00. Forte Slick City ST tires (26 X 1.25) were another $10.00 each at Performance.

I've ridden the bike well over 200 miles so far, and it's plenty rigid for the steep climbing / descending I do on the paved Rocky Mountain roads I normally ride. I'm planning to make a 3 piece take-apart handlebar and possibly add cable break connectors.

Below are a few pics I took today of the bike before, during, and after loading into the front and rear trunks of the car.

Simple is as simple does ..... Tom

After unbolting the SS machine screws / lock nuts, the sleeves slide forward to separate the frame sections.


Everything in this pic will be loaded into the Porsche. I roller ski and bike on Mondays and Friday's and with the exception of the panniers, this is the gear I use.


Take-apart and assembly take about 5 minutes each. The rack is optional.


The folded bike frame and cycling gear fit into the rear trunk. A PVC liner with velcro attachment keeps the trunk clean.


26" wheels, roller skis and gear fit into the front trunk. Ski poles fit between seats.


Earlier this year I made a bike rack for the Boxster. I've owned this Cannondale ST 400 for 25 years .


My favorite homebuilt rack setup ... Specialized TriCross Comp and Triumph Sprint

Last edited by werks; 10-22-10 at 07:50 AM.
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Old 10-16-10, 03:26 PM   #2
jur
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Wow! I like your ingenuity! Looks strong enough for not too strenuous riding. Regular inspection of those tubes for cracks should be fine.

Just a side observation: Going by your motorised transport, you aren't strapped for cash. So you could consider on of the higher quality folders for dual duty... Bike Friday, or Pacific Reach comes to mind. Or the new Dahon Jetstream.

(OTOH, perhaps you are now strapped for cash after the motorised transport, )
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Old 10-16-10, 03:33 PM   #3
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looks like your trunk has enough space for a bike friday and will definitely save you time in bike disassembly and assembly.
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Old 10-16-10, 04:00 PM   #4
werks
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Wow! I like your ingenuity! Looks strong enough for not too strenuous riding. Regular inspection of those tubes for cracks should be fine.

Just a side observation: Going by your motorised transport, you aren't strapped for cash. So you could consider on of the higher quality folders for dual duty... Bike Friday, or Pacific Reach comes to mind. Or the new Dahon Jetstream.
Thanks for your comments. It has nothing to do with money. I just like to build things when I can, automobiles and motorcycles excluded I don't require 30 second assembly, only small enough folded size for the trunk of my car.

I'm familiar with BF, Dahon, etc., but I wanted a full size bike for the workout riding I do. In fact, the Dahon Matrix was in part a source for my own simplified design.

Rita and I ride a Trek tandem. Here's a pic from yesterday.


Tom
http://www.yostwerks.com/ - My free folding kayak building manuals

Last edited by werks; 10-20-10 at 09:04 AM.
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Old 10-16-10, 10:30 PM   #5
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Very nice! The bike also look good.

I wonder if a split TSR will fit in a Boxter's trunk. I always assumed it will not but seems that I was wrong.

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Old 10-17-10, 10:29 AM   #6
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So much for $400 for an S&S conversion!!! Interesting what one can do - I like the "outside the box" thinking.

I am assuming the OP doesn't weigh 250+ lbs - shouldn't with all that exercise!...lol

Would echo what jur said, watch for cracks and other signs of stress - This is kind of a "beta test" situation.

Lou
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Old 10-17-10, 10:32 AM   #7
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The eventual failure of that take-apart frame will be at the bolt holes, although you're more likely to firstly see distortion in the alum sleeve. If you find that one day the frame tubes slide in too easily from the norm or not well at all then don't try riding it.

I did try something like this years ago but in steel, eventually I had to scrap it as it failed at the bolt holes of the join as I'd relied on clamping force, nothing was brazed or reinforcements welded in. Those frame tubes are meant to twist and flex, as well there being places along a tube that may be tapered and too thin to just drill holes through and clamp something down to. If you sit on your bike, grab each end of your wide MTB bars as normal but apply up and down movement to the bars (the sort of movement the bars normally soak up and you don't notice as you ride) you will see the headtube moving side to side, like a tower in an earthquake, then look to the movements conveyed to the rest of the frame. If you like, imagine the top and downtubes as caught in that earthquake, the frame tubes grinding and slapping at the anchors of those stainless bolts holding the fixtures together. The weakest point is the lip of each drill hole and the normal twisting and flexing will work against that.

So take care.
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Old 10-17-10, 12:16 PM   #8
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Thanks... Constructive criticism is always welcome

I'm watching closely for any signs of cracking, excess wear or flexing, etc.

I've built a double tube sleeve setup with the one you see using 6061-T6 (1 3/8 X .049 wall) , and a second cover sleeve of 6061-T6 (1.5" X .049). These will telescope and provide a bit of redundancy, and since the tubes slide apart, are easy to inspect.

Imperial tubing has one advantrage over metric in that it can telescope through the full range of diameters in 1/8" increments. I planned to use 6063-T832 with wider .058 wall, but I didn't have it in the correct diameter tubes. CrMo or mild steel is another option should the need arise.

There is a tendency to overbuild, as I discovered in the many years I've spent building kayaks. My folding boats are built light and flexible, and have proven very durable over many years of use. Of course, the stress on a bike frame is different than a kayak, and I'll be on guard for the potential failures already mentioned.

Here's a couple of my folding kayak frames... one is 6063-T832 ( the shiny one), and the other is 6061-T6. The 3/4" tube section connect with 5/8" inserts. Both 6063 and 6061 have about 40,000psi tensile strength. In the folding kayak world, folding actually means take-apart, unlike folding bikes.

I plan to build a couple of lightweight bike frames this winter using oversize aluminum tubing.... Tom

Aluminum / HDPE frames with PVC skins

Last edited by werks; 10-17-10 at 01:38 PM.
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Old 10-17-10, 02:23 PM   #9
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Love it.
Please keep us updated with how the bike and, especially, the joint holds up.

I prefer the concept of a demontable or demountable bike over a folder. I bought a Montague Paratrooper which can be split for airline travel. I also put 24 inch wheels on to make packing in a airline legal suitcase quite simple.

In Japan I saw a Panasonic touring bike set up as a demontable. ( http://cycle.panasonic.jp/products/pos/osd6.html ) The frame splits in a similar place to yours. However, the tubes are clamped together rather than bolted together. Dahon also make a few similar demontable bikes.

Regards
Rob
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Old 10-17-10, 09:13 PM   #10
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Robsta ... Please keep us updated with how the bike and, especially, the joint holds up.

Thanks ... and I'll let you know how this experiment plays out.

Tom
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Old 10-17-10, 09:26 PM   #11
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looking awesome!
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Old 10-18-10, 04:19 AM   #12
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I was thinking, would cutting some steel tubes to shaped to fit flush inside the bike's frame tubes, from drill hole to the corresponding hole, do anything to help relieve some of the risk of distortion? By this I do mean tubes, the steel bolts are meant to pass down these tubes. They'd have to be fixed in place, perhaps just bonded with JB Weld would be enough?

Something more for me to experiment on...

Last edited by just4tehhalibut; 10-18-10 at 04:21 AM. Reason: clarity isn't perfection but it's nice to see where you're going
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Old 10-18-10, 08:07 AM   #13
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...would cutting some steel tubes to shaped to fit flush inside the bike's frame tubes, from drill hole to the corresponding hole, do anything to help relieve some of the risk of distortion?

A small section of steel tube inserted in place only to support the drilled bolt holes might be a way to reduce wear in this drilled area. Though I'm not sure that distortion, if there is any to the steel frame tubes, would be affected any more than using thicker sleeves. Then again, it certainly is worth looking into.

It's time to head out for another test ride

Thanks again for your input ... Tom

Last edited by werks; 10-18-10 at 08:46 AM.
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Old 10-20-10, 08:13 AM   #14
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Testing, Testing, Testing

Here's a few pics from yesterday's ride through Red Rocks. There are three fairly good climbs / descents along this loop, so I thought it would be a good stress test for the folder. The frame feels as rigid and stable as before the surgery.

Morning temps at my place (9,000ft) are below freezing, so the 40 minute drive to the base of the foothills (5,800ft) provide at least 15 degree warmer starting temps ... A change in altitude is like a change in latitude

After assembly it's time to ride ..... Deer Creek Lake Park, Morrison, Colorado










Red Rocks Natural Amphitheatre ... Great acoustics, great concerts, and the steepest climb of the ride !


100 million year old footprints along Dinosaur Ridge ... Same loop, earlier ride.


It's warmed up enough for a top down drive home ...

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Old 10-20-10, 09:37 AM   #15
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Geez, too bad you have to ride in such an ugly place Beautiful and I'm glad your bike adaption is working out so well. It's nice to be a handy Andy. If I tried what you did, Ebay would have two listings for custom half bikes!
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