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Folding Bikes Discuss the unique features and issues of folding bikes. Also a great place to learn what folding bike will work best for your needs.

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Old 08-26-09, 08:44 AM   #1
OrangeClownBike
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R20bent?

I've had an idea.....

If you take a folding R20 and unbolt the joint so you have a front and back part.

Take a "spine" that is a length of (probably rectangular section) tube, and bolt the front and back parts of the bike onto the "spine"

You now have a long wheelbase R20.

If the spine:
* has at the front end a bottom bracket with pedals and chain ring
* has at the back end a seat (purple bit)
*has in the middle a "headset" with handle bars

you can remove the R20 seat, remove the R20 handlebars and replace with a stub steerer tube with a little side tab on.

The steerer on the spine headset is connected to the stub steerer in the forks by a rod linkage (red line)

The R20 pedals and cranks are removed and a modified (crank arm is sawn off) is bolted on.

The spine pedals are connected to one of the double sprockets on the original R20 bottom bracket by a chain. The other sprocket on the R20 bottom bracket connects to the rear hub as per normal.

Brakes and gears rerouted to the new spine handle bars.

I give you the R20cumbent bike (R20bent for short)

Comments, abuse, praise, donations etc all welcome!

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Old 08-26-09, 10:06 AM   #2
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That seems inspired - your diagram shows nicely what you intend and the bargain is you don't damage the original frame. I think you should do it - doesn't even look that complicated.

+1 on the square section - best way to bolt the Twenty to the frame. Be aware the bolts are not metric, so you need imperial sized nuts to do this.

Also nice to see you used Sheldon's bike as the base. He would be proud of such an audacious project.

Tempted to have a go myself - but that I had the space, tools and welding skills....
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Old 08-26-09, 10:29 AM   #3
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Brilliant!



I really don't have much more to say other than I can't wait to see pics.
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Old 08-26-09, 11:20 AM   #4
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Now I have to wear socks with my sandals!
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Old 08-26-09, 03:29 PM   #5
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i might have a go at this despite not having the space tools or welding skills.

might have to wait a bit as I'm moving house at the mo but will have more space in a few weeks.

Was thinking I need a wide spaced rear triangle to fit a NuVinci hub I have. My current R20 has a narrow hub (duomatic), not really susceptible for a recumbent.

The front end of my R20 would do fine for this (apart from a rubbish front brake) the front fork is stock so swapping the steerer out would be a doddle.

I'll look for a scrapper R20 rear end I think.....
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Old 08-26-09, 08:06 PM   #6
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I have seen a 'bent built up out of Raleigh parts complete with the 3 speed SA hub. Here is the only picture I can find of it, but I might see it again in a few weeks, if so I will grab some more pictures of it. IIRC MnHPV had something to do with it.

Aaron

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Old 08-28-09, 03:06 PM   #7
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Somebody in this forum bought a readymade kit to transfer a 20" folder to a bent. There is pix of him riding it with a child in a child seat. Hope he reads this and posts a picture.

Edit: Here it is Goodbye to my folding recumbent
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Old 08-28-09, 03:43 PM   #8
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Liked the link

About halfway thru the thread was this:



Brilliant!

If I leave the original seat, pedals and rear shopping baskets on and I would have a tandem-folding-recumbent-utility-minivelo!

All I need now is to add electric assist and I can be active on 6 bikeforums at once!

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Old 08-31-09, 02:49 PM   #9
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I have seen a 'bent built up out of Raleigh parts complete with the 3 speed SA hub. Here is the only picture I can find of it, but I might see it again in a few weeks, if so I will grab some more pictures of it. IIRC MnHPV had something to do with it.

Aaron
That's mine. I used a 1964 Raleigh woman's frame bike and added just three tubes for the pedal boom and a seat rail, so it was quick to throw together. Handlebar assembly is completely standard 3 speed bars, grips, levers and shifter on a tall stem. Crank was an alloy "Raleigh" branded Sakae shortened to 158mm with an adapter to allow the use of a BioPace chainring. (I won't use round rings on a 'bent)

The composite photo shows the design evolution, with some PhotoShop'ing to predict the final layout.



16 and 20 inch wheels and fenders are from a 1965 Moulton and a 1973 Raleigh "Twenty". Currently it has a S5 five speed guts in the shell.

I used it for a couple of years on the http://3speedtour.com when my shoulders were in bad shape. Unfortunately I no longer can ride it with the high cranks due to circulatory problems, so it's looking for a new home. I have an extra R20 that could be turned into an LWB bent with low cranks.

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Old 08-31-09, 06:33 PM   #10
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How tall a rider will that beast fit?

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Old 09-01-09, 02:20 AM   #11
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I'm wondering what these are like to ride from a practical and ergonomic point of view. How easy is it to look behind you from that riding position? I like to get a really good look behind before I commit to overtaking parked cars or turning across the carriageway (turning right here in uK). I get a pretty good view all around on an upright because my spine joints from the hip upwards are sharing the rotation, whereas from a sitting position with back support, it would only be the spine from the shoulders and neck. This might not be an issue for a nineteen year old, but I am forty years further down the road than that. An inability to look behind efficiently would likely lead to an untimely death on overtaking and turns across the traffic stream.

Last edited by EvilV; 09-01-09 at 02:24 AM.
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Old 09-01-09, 04:51 AM   #12
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I'm wondering what these are like to ride from a practical and ergonomic point of view. How easy is it to look behind you from that riding position? I like to get a really good look behind before I commit to overtaking parked cars or turning across the carriageway (turning right here in uK). I get a pretty good view all around on an upright because my spine joints from the hip upwards are sharing the rotation, whereas from a sitting position with back support, it would only be the spine from the shoulders and neck. This might not be an issue for a nineteen year old, but I am forty years further down the road than that. An inability to look behind efficiently would likely lead to an untimely death on overtaking and turns across the traffic stream.
Helmet or handle bar mirrors, old chap.
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Old 09-01-09, 07:00 AM   #13
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Helmet or handle bar mirrors, old chap.

Na - I like to look Death in the face without contraptions getting in the way... LOL

In any case, I've had too many close shaves on the motorways when pulling out after looking in my wing mirror and not having seen some juggernaut overtaking me and hidden in the blind spot.

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Old 09-01-09, 09:20 PM   #14
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Na - I like to look Death in the face without contraptions getting in the way... LOL

In any case, I've had too many close shaves on the motorways when pulling out after looking in my wing mirror and not having seen some juggernaut overtaking me and hidden in the blind spot.

I know what you mean, believe me.

In fact, this morning as I was riding my tandem to pick up a blind guy I ride with, a work vehicle with a trailer attached pulled across the road in front of me, then stopped.....leaving me either to smash into the side of his trailer or take evasive action and ride up a driveway and onto the nature strip. I chose the second option...then gave him a harsh mouthful of........not swearing.

I have his name....I might pay him a late night visit
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Old 09-02-09, 07:09 AM   #15
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That would be a hair raising experience (Your late night visit - not the near accident).



The stupidity of some road users is simply mind boggling. The art of driving should only be open to those of above average intelligence and proven common sense. All the rest should ride bicycles.

ducks missiles flying his way.
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Old 09-02-09, 06:14 PM   #16
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Quote:
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I'm wondering what these are like to ride from a practical and ergonomic point of view. How easy is it to look behind you from that riding position? I like to get a really good look behind before I commit to overtaking parked cars or turning across the carriageway (turning right here in uK). I get a pretty good view all around on an upright because my spine joints from the hip upwards are sharing the rotation, whereas from a sitting position with back support, it would only be the spine from the shoulders and neck. This might not be an issue for a nineteen year old, but I am forty years further down the road than that. An inability to look behind efficiently would likely lead to an untimely death on overtaking and turns across the traffic stream.
Although I can't comment on that particular one-off bike, I've ridden the similar Lightning P-38 and have switched my main ride from a folder to a Bacchetta in an attempt to curb my train usage.

That being said, IMHO an upright bicycle (folder or nonfolder) definitely has inherently superior visibility (both in terms of seeing and being seen). However, the value of this inherent superiority is limited because the roads are really designed and evolved for recumbent vehicles because the body position in a car is recumbent. So if there isn't enough visibility from the recumbent position at a certain spot on the carriageway then the authorities typically add traffic controls to quell the subsequent bloodbath. Combined with the fact that automobile drivers also have their roofs to block their view, I think recumbent bicycles are perfectly practical and ergonomic road vehicles.

Personally, however, I like to maintain an edge on the cagers, so I ride a highracer so I can still look over them and I use an airzound so my horn is louder than theirs in addition to using a mirror. Overtaking and turning is always accompanied by a look in the mirror, a look over the shoulder, and an offensive blast.

You might want to check out bentrideronline for more info because most of the guys there are also old farts.

Last edited by chucky; 09-02-09 at 06:49 PM.
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Old 09-03-09, 07:23 AM   #17
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I'm wondering what these are like to ride from a practical and ergonomic point of view. How easy is it to look behind you from that riding position? I like to get a really good look behind before I commit to overtaking parked cars or turning across the carriageway (turning right here in uK). I get a pretty good view all around on an upright because my spine joints from the hip upwards are sharing the rotation, whereas from a sitting position with back support, it would only be the spine from the shoulders and neck. This might not be an issue for a nineteen year old, but I am forty years further down the road than that. An inability to look behind efficiently would likely lead to an untimely death on overtaking and turns across the traffic stream.
I commuted into downtown Minneapolis on a 'bent for 15 years, In the dark in the winter. Having to cross 4 lanes of traffic to turn left on our one way streets. Using a 3rd Eye helmet mirror, larger than most, I could turn my head and pan across everything behind me. The only time this was a problem was when it was so cold my breath would freeze on the mirror
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