Converting my recumbent to...
Thread started by bentstrider
at 12.18.08 - 2:10 pm
either a 26" or 700c wheel size for the rear.
I extremely want to do this as opposed to purchasing another recumbent for the mere sake of having the added momentum/speed of a 26" or 700c.
The 20" on the rear really sucks ass when I'm trying to keep up with a fast group, and it doesn't really hold cargo as well as my Hummer(see stereo).
To me, this seems like a relative ease of lengthening the rear-triangle section to adequately fit the rear-wheel in the back properly.
So, Bikerowave, Bike Kitchen, Bike-Oven people, any suggestions, or a day I could bring the frame in?
I got money!!!!
That and the two, LBS's up here are only interested in selling new parts and telling you to get fucked when it comes to DIY.
What's the 20" tires you've tried so far?
I really liked the comets in the past...
Also take a look at the recumbent tires available..
12.18.08 - 2:22 pm
I already tried the tires, but I'm under the assumption a larger wheelsize will help me maintain momentum.
12.18.08 - 3:32 pm
well, it will, but aside from cutting the frame and lengthening the rear triangle, a pretty hefty operation, you're stuck with the 20.
12.18.08 - 4:03 pm
What tires have you tried Adam?
12.18.08 - 4:29 pm
Increasing the rear wheel diameter on your recumbent will do two things: raise the gearing, and change your steering geometry. The bike will steer quicker and may be less stable. You can change the gearing a lot easier with chain ring or cog swaps.
More inertia? Yes, of course. But that will mean more power required to spin up or accelerate. You can get more inertia by swapping for a steel wheel of the same size, but I don't think this is what you want to do.
About the best you can do is install high performance tyres and gear up if necessary. And adjust the recline of your seat as far back as you can to minimalize air resistance at speeds over 15 mph.
12.19.08 - 8:15 am
I'd bet the recumbent was designed with 20" wheels to keep the center of gravity low for stability. As long as you can set up a high gear ratio, you'll be able to keep up with big wheelers.
Land speed records have been set by bicycles with 18" wheels.
12.19.08 - 10:35 am
Bikes with a lower center of gravity will steer quicker. This of course being that everything else is the same.
Some of the current speed records held are on small wheels. The fastest speed on an upright bike is over 51 mph and on 17 inch wheels. The fastest speed on a bike, 152 mph was set on 20 inch wheels. And the fastest speed un-assisted, over 81 mph were on 24 inch wheels.
What makes the taller wheel faster is that it rolls over bumps, dips and holes better than smaller wheels. Eliminate that, and smaller wheels are faster and easier to keep up at speed.
12.19.08 - 11:31 am
"The fastest speed on an upright bike is over 51 mph and on 17 inch wheels."
Oh I forgot to mention, this record is over 22 years old! That's incredible when you consider the rate of R&D in bikes.
12.19.08 - 2:19 pm
of course that's not including gravity assisted...
I've been over 60 on a road bike.
12.19.08 - 2:24 pm
Well, my seat will not lean very far back on my bike without forcing my knees into my face.
So, in the near future, I'm looking into an Under-seat, steering 20"/26" model from Actionbent.
Cool thing about these ones is the fact that any store-bought accessories will go on without any problems, and they're more compact for buses, trunk storage., etc
Which will be a plus for the day I'm finally able to get back Over-The-Road.
02.27.09 - 7:04 am
Bentstrider - Check out the plans at atomiczombie.com.
If you can find a metal shop near you, you might be able to build a custom recumbent pretty cheap.
02.27.09 - 7:25 am
Here's a little doctoring of what I have in mind.
04.3.09 - 6:34 pm
Maybe your should consider simply adding an Xtra Cycle
04.3.09 - 6:44 pm
It could work, but first I'm going to weigh the cost of "welding vs. new-bike vs. xtra-cycle".
04.3.09 - 7:23 pm
with that long of a chainline, welding frames together will probably be problematic.
04.3.09 - 7:29 pm
I could always make, or order some additional idlers to guide the chain along.
04.3.09 - 7:35 pm
Essentially, I'm using the rear-triangle of this Trek 820 frame I still have sitting around.
04.3.09 - 11:30 pm
even with extra idlers (is that what they are called?), having a frame that isnt perfectly straight would be like having your chain be in the big ring of the front ring and the small in the back. it would rub on the derailleur and cause lots of problems. your chain would wear out 100x quicker, the chain would come off the gears more than it should, it would be super noisy, etc etc.
04.4.09 - 1:56 am
I'll see what happens.
If anything, I might just leave the BB on the frame triangle and utilize that as another reducer as well.
In the end, if that doesn't work, I might just cave and go with an Actionbent Jetstream.
04.4.09 - 2:17 am