Friday, October 23, 2009

thoughts on 'bent bike products - and others

D: I loaded up my Cruzbike with groceries last week.
I have two folding baskets mounted on a mountain bike rear rack.
They are nice - they perfectly hold those reusable grocery bags.
But each basket only holds one.
They were a bugger to mount. The baskets assume road-bike rack dimensions.
The mountain bike one is fatter.
I had to pry apart the mounting system. It looks pretty rough.

I pondered tacking a third one on top.
But the rack is a standard width.
It presumably is made for pannier strap width.
BUT that is too narrow to mount a third basket on top.
It would overlap with the side folding baskets.
Plus the baskets are not designed to fold straight down.
They *could* be though...

Problem is that a wider rack on top would not mount panniers properly.

I have never used panniers. I don't like them. I think they are bad design.
I won't leave anything unattached on my bike when unattended.
Off the bike, they are not ergonomic for human use.
What I'd want is a backpack or rucksack and a way to mount them on a bike.
Not everybody sees things this way.

So how to mount a pannier but also a full-width basket?
Some god-awful pivot point on top of the rack.
I say screw the panniers.

I cannot find a good pic of the Cruzbike seat mount at the rear.
Trust me when I say it slides into a standard seat mount post.
Anyway, basically you need a rucksack mount there.
Cut a slot along the length of a seat tube width pipe.
Have this piece on a telescoping mount.
Frankly, a square tube arrangment works better above the bottom.
It won't rotate.
Have two hooks to simulate shoulders to mount the rucksack.
When not in use, it slides down behind the seat.

Why all this?
1) a bike that mounts THREE full size folding baskets - one proprietary that folds straight down.
2) a proprietary Cruzbike-specific backpack/rucksack mount.
Talk about your niche target market!

On my Mark I design, I planned to build a rucksack mount into the back of the seat.
This would suspend the rucksack mount on the seat suspension.
A fully loaded rucksack would necessitate a change in the elastomer suspension system.
A 50 pound rucksack will change the elastomer choice.
Why a rucksack mount?
The rucksack goes with the rider once he is off the bicycle.
It is rider, not ride-centric.

Recumbents are nice, in that the luggage is BEHIND the rider potentially, not UNDER him.
Lower air drag.
This is not true of my grocery baskets.
But it would be true of a rucksack.

I think maybe you could mount two more baskets under the seat.
The easiest way would likely be to modify a rear rack mount to attach to the bike frame.

Thursday, October 15, 2009

Mr. Tetz graciously responds

How much power do you suppose yer motor of choice could handle before breaking?
....Probably around 1,000 watts. It wouldn't break but the winding might burn up. The model airplane guys often get 1,000 watts out of the motors for a short time (few minutes) (of course they have more cooling air that we do).

One problem for a bike though is the gear box. It would have to be huge. Higher rations to start out with and much bigger gears. My gear box is extremely light (several ounces) because I am only delivering 100 watts. Even if I wanted to double the power I would have to go to a bigger gear box.

What happens when your looking for higher power is the system grows in weight by a lot. Higher weight means the battery has to be much bigger adding even more weight. From 5 pounds it can quickly grow to 15 pounds.
Accelerating 15 extra pounds take a lot more power.

One last thing. Trying to start from a stop is very tough to do. My system is limited to no lower than 2 mph. Gearing is chosen to get he optimum range of assistance. Many commercial assists are also limited by the same gearing set ups.

So if your only looking for low end help and limited speed you can do it mainly with a high ratio gear box. The motor is easy.

I use my system for acceleration a lot. to help me get up to cruising speed.
D: I had hoped to use the supercapacitors in lieu of more batteries. They might hold up for a few seconds.
Yeah, the gearbox seems unavoidable.
I wonder if any motors have a high-torque design in mind.
Maybe model airplane motors aren't the best place to start.

Wednesday, October 14, 2009

folding bike. thought on bike rack 'n bent bike

I'd post a pic, but my POS IMac won't let me change title in 'save as'. Grr..

Re: bent bike.
A short wheelbase could have a pivot for the front boom.
It could hinge up and overtop of the seat area.
This would allow it to pretend to be a normal bike to fit in a bus bike rack.

I reiterate that a swan-neck-like curvature would also allow it to absorb energy on impact.

I was looking at some high-end city-cruiser bike concept.
It weighed in at only 35 lbs with high quality steel components.
But with the same motif but aluminum... 20-30 lbs??

Cruzbikes - been riding mine lotsa.
The 24" youth frame tires mean I spin out going downhill at all.
I swapped out a cog but the chainring would have been prohibitively expensive to swap out.
I have wayyyy too many low end gears.
Stability of the frame means I cannot spin in very low torque slower than a certain speed.
I'm sure I have a handful of redundant low end gears.

Starting on an incline, what a bugger!
I am all about the power assist on takeoff.
I think on a decent hill, if I stopped, I'd be screwed.
Which is likely, since the front wheel drive starts skipping due to lack of traction.

That front boom, even with aluminum cranks, is massive!
Yup this kit would be sooo much better out of aluminum for the tubing.
It would also work with motif better.
Honestly the thin steel parts would look more at home on a road-bike frame.

I seem to have finally worked the kinks out of the chain and gearing.

To reiterate the kit should
1) not have 2 kits of parts and instructions
2) should have the additional neck adapter
3) a kickstand mount for a bottom bracket and
4) a locking mechanism to keep the front boom in line with the bike frame while parked

I'm curious how light an all-aluminum frame would be if I chopped up two beaters and just cobbled them together.
The seat would need to do all the adjusting, of course.
I'm also curious about under-seat-steering.

Thoughts on this winter's project- designing the Mark II aka cheap Greenmachine knockoff.

Yup I'm thinking a brief, high torque electric (or air) power assist is a good idea.
It addresses a limitation of a SWB 'bent frame.
I'm thinking Tetz's lite power assist, but with a buncha capacitors that can slowly charge off of a battery. Alternatively it could use power conditioning of a wheel dynamo. I wonder how hard the Reelight kit would be to adapt.
I'm intrigued by powering a USB appliance like my music player.
5v, 500 ma it appears.

I rather like the idea of the generic cigarette car adapter.
On a lower 'bent, the idea of a cattle prod for dogs sounds pretty good! <:

9v, 80-225ma.

The brief hi-torque power assist power supply would be well suited to this.
With 10x the power of a battery.
Plus I learned the hard way that many batteries die in sub-zero celsius weather.
Which just makes the Reelight more attractive!
Which could charge capacitors...

I'm gonna ask Tetz about this.

Wednesday, October 7, 2009

bike with collapsing WHEELS!

Sorry, no pic.
I am nearly helpless on a Mac.

It took me this long to figure out cut 'n paste.