
A Shock-Absorbing Wheel for Bikes and Wheelchairs - jdnier
http://www.wired.com/2014/05/an-amazing-shock-absorbing-wheel-for-bikes-and-wheelchairs/
======
atourgates
Could someone explain this bit to me:

"In traditional wheelchair designs up to 30 percent of expended energy is lost
because they lack suspension."

It sounds an awful lot like bullshit.

I know nothing about wheelchairs, but I just can't see how you're going to
increase efficiency by adding suspension.

In bicycling, suspension reduces your efficiency when you pedal. It's why XC
and all mountain MTBs have various mechanisms to lock out suspension during
pedaling (some of which are quite clever), and high-end dedicated XC bikes
have no rear suspension at all.

I don't think there's anything magical about moving that suspension into the
wheel that would suddenly add efficiency.

As others have noted - this will never make it into mainstream cycling. The
most noticeable weight on your bike is the weight on your wheels. If you added
2 lbs of weight to your frame, it would be much less noticeable than adding
1lb each to your wheels.

Even if the article's claims of somehow increasing efficiency by adding
suspension were true, I'll be they'd be more than negated by the added weight
on the wheels.

~~~
msandford
>"In traditional wheelchair designs up to 30 percent of expended energy is
lost because they lack suspension."

>It sounds an awful lot like bullshit.

It's not necessarily bullshit and in fact could be quite true. This is one
reason why cars drive on air inflated rubber tires instead of solid metal
ones. It's also one reason why trains are more efficient than cars, they have
a VERY smooth "road" to travel on and thus don't lose any energy to up-and-
down movement.

If you believe that suspension losses are trivial then I invite you to find a
road with rumble strips (to wake up sleepy drivers who slowly veer off the
road) and to ride it on a road bike with skinny tires at a very high pressure.
Then ride it again with a non-suspended (or locked out) mountain bike with
it's much larger tires. Then ride it again with a mountain bike with a
suspension.

Here is an informal study doing precisely that for different sizes of road
bike tires: [http://janheine.wordpress.com/2012/08/12/suspension-
losses/](http://janheine.wordpress.com/2012/08/12/suspension-losses/)

You'll find that the pedaling losses from a suspension might get swamped by
the benefits. So it turns out that the optimal solution is relative.
Furthermore a person in a wheelchair isn't going to have the same kind of
60-120 RPM cadence (1-2Hz, but then double it since there are two legs, so
2-4Hz) that a cyclist would. You can do a lot of higher frequency bump
reduction for wheelchairs and not sap the users energy for the wheel-push
stroke which takes multiple seconds.

What this really has to do with is the size of the surface texture relative to
the size of the wheels and the ability of the tire to deform. A lot of wheel-
chairing happens on sidewalks which are fairly smooth but have expansion
joints every 3-10 feet. Or on blacktop which is smooth relative to a car's
tires which are air inflated but not relative to a wheelchair's which are
solid rubber. Or what about older concrete, or tile, or one of any of the
other myriad surfaces which aren't perfectly flat?

> Even if the article's claims of somehow increasing efficiency by adding
> suspension were true, I'll be they'd be more than negated by the added
> weight on the wheels.

It all depends on the kind of riding you do. I ride long distances on the road
for training (not racing) so I don't have need of a wheel that has low
rotational inertia. As such I could accept a weight penalty for the sake of
comfort. I own a titanium road frame which is "heavy" by road standards and I
put a tandem fork on it for extra strength, and I ride 40 spoke wheels. The
idea that weight is paramount bar none might be true for professional cyclists
but not for everyone. To a great many people it's only a small factor when
making decisions.

EDIT: formatting and moving the link

~~~
vacri
_a car 's tires which are air inflated but not relative to a wheelchair's
which are solid rubber._

Plenty of wheelchairs have pneumatic tyres, including the ones in the article.

~~~
msandford
Point taken. I was thinking of the wheelchairs I've seen people pushed around
hospitals in which don't necessarily correspond to what people buy for
themselves for the long term.

~~~
lizzard
Those are absolutely terrible wheelchairs, built to the specs of 50 years ago,
heavy and uncomfortable. They are very difficult to get around in. No one
should have to use those.

------
SeanLuke
So.

Suspension wheels have been around for quite a while now. The most well known
is the Pantour.

[http://www.atob.org.uk/bicycle-accessories/pantour-
suspensio...](http://www.atob.org.uk/bicycle-accessories/pantour-suspension-
hub/)

The Pantour does suspension inside the hub. That's not a lot of room so we're
talking a centimeter of suspension. But that's all that many bikes can take
anyway, since they have rim brakes and more suspension than that would move
the rim too far from the brake.

A similar approach, albeit more high-tech and intended more for efficiency,
was recently showcased by Gosiko.

[http://www.bikerumor.com/2013/03/05/nahbs-2013-gokisos-
amazi...](http://www.bikerumor.com/2013/03/05/nahbs-2013-gokisos-amazing-
suspension-bicycle-hubs/)

Though Softwheel gets credit (?) for using what amounts to shock absorbers, a
much lighter and more robust approach has been done for a while now, using
leaf springs:

[http://www.gizmag.com/loopwheels-suspension-bicycle-
wheels/2...](http://www.gizmag.com/loopwheels-suspension-bicycle-
wheels/27129/)
[https://www.youtube.com/watch?v=O11hFiu43RQ](https://www.youtube.com/watch?v=O11hFiu43RQ)

Here's a few problems I see with the Softwheel, at least for bikes (I have no
idea about wheelchairs).

1\. It would appear to be very _very_ inefficient. As the wheel is turning,
each suspension spring is constantly being pushed and pulled. One would think
that a single suspension, like a suspension fork or the Pantour hub, would be
much more efficient.

2\. It's likely heavy. Rotational inertia could be a problem.

3\. It's likely not very strong. Perhaps the suspension compensates for this a
bit.

4\. It'd only work with disc brakes.

~~~
pkulak
1 is the real deal breaker here. People fill their tires to 140 PSI just to
get rid of a little bit of the friction caused by the tire deforming as the
wheel turns. That has to be nothing compared to actual shocks. It must feel
like riding through dry sand.

~~~
jessaustin
I think the whole bicycle wheel thing is just a ploy to scam clueless
investors. No one who had ever tried to ride one of these wheels up a hill
would think they were a good idea on a bicycle. And the descending stairs
thing? I've descended much steeper on my regular old hardtail.

Since motive force is applied to the _rim_ of wheelchair wheels, it probably
works fine for those.

------
digikata
For wheelchairs where the angular velocity is fairly low, it looks like a
great product. For bikes, you can see on the demo video how the back wheel is
out of alignment. The faster you go the more noticeable it would be. Even if
you take care of the original factory calibration, over time I would think it
would get worse from uneven performance from the shocks as they wear.

------
mgberlin
This seems like it might work well for wheelchairs, where performance is not a
large issue. For bicycles though, it's turning a component that was once
static into one that's rotating. This means the rider will have to overcome a
whole new set of forces just to get the wheel moving. There's a reason people
pay such a huge premium for very light rims and tires, and go through the
trouble of not having inner tubes.

~~~
Someone
Is performance really not a large issue for wheelchairs? I would think the
elderly would not have the strongest arms, and younger, powerful riders would
in many cases prefer speed over comfort. Yes, it might be useful in rough
terrain, but that is precisely the terrain where the loss of power due to
inefficiencies in the wheel might mean the difference between getting over
that bump or not getting over it. I think there is little room between this
and just mounting (much) wider tires and using less tire pressure.

~~~
lizzard
Performance is a huge issue. A better performing wheelchair makes a difference
in our independence and range we can go on our own. It also makes a big
difference in the wear and tear on our shoulder joints and hands.

------
ranprieur
Both videos are lame. Lots of shots of people riding around being all
inspiring, and almost nothing about how the wheel actually works to absorb
shock.

~~~
nnethercote
And nice music. Don't forget the music.

------
Crito
I can't press Ctrl-F to initiate a search on this page without it pulling up a
picture slideshow, taking me away from the content that I wanted to search.
What a stupendously senseless display of hostility to users.

For anyone else who was wondering, there seems to be no mention of rolling
resistance.

~~~
logicallee
A commenter on the article stated, "Putting the wheel's axle off center
through a system of articulated links is bound to increase effective rolling
resistance." and another said "This is going to feel like you're riding on
sand."

~~~
Crito
Yeah, that is my suspicion as well. Even just the difference between street
tires and mountain bike tires is very noticeable on a bike.

This product might be worth it if you are using a wheelchair over rough
dirt/ground, but I doubt this sort of wheel will become very popular with
bicyclists _(bicyclists already have shocks built into their bike frames, if
that is the sort of thing that they need for their particular application)_.

------
lizzard
The value of shock absorbing for manual wheelchairs isn't just in efficiency,
it would be also quite valuable for making it less painful to go over bumps.
Even going down a relatively city sidewalk is exhausting from the bumps and
cracks, because jolting adds to the pain of sitting upright if your spine or
pelvis are already in pain. Efficiency is also great though!

------
Zigurd
If the suspension elements don't wear perfectly evenly or are not perfectly
evenly charged to begin with, it will be like riding on an out-of-round wheel.
That is, instead of absorbing bumps, the suspension will feel like you are
riding over regularly spaced lumps. It will be fiddly to maintain.

You also use one third of the suspension at a time. Trading what the
suspension spokes weigh versus a suspension with a single spring and shock per
wheel, is also probably going to be a favorable trade-off.

Some quick Googling shows there are existing suspension wheelchairs that look
like they use mountain bike rear suspensionspring/shock components, and it
looks like there is sufficient room under the seat to accommodate a
suspension.

------
logicallee
I am shocked at the (very high) quality of comments on the article. (Just
scroll down).

Better than HN. I didn't notice what domain I clicked through to, made me do a
double-take, am I on Scientific Mechanics or some super specialized blog?
Kudos to the Wired comments team.

------
7952
Not really sure what kind of bikes this would be useful on. The most basic
form of shock absorption is the tyre, and you can run with higher volume tyres
and lower pressure to make it more comfortable. Of course on the road this
will slow you down so people don't tend to do it. For the kind of urban
obstructions in the video you could ride perfectly well (and with more fun) on
a fully rigid frame (like a BMX). For more serious mountain style riding you
need rims that will not be deformed by rocks etc and just keep rolling over
obstructions.

------
DonGateley
Other than the spiral flexures that NASA uses this seems to be rather unique
in that shock is absorbed in two dimensions rather than one. No matter from
what direction jerk is applied the wheel will absorb it in the same or a
similar direction rather than just absorbing the vector component that is
along the direction of a linear shock absorber.

That means it will absorb more of the shock and be more comfortable. If people
know of another mechanism that has this characteristic I'd love to know about
it.

------
noir_lord
If there was a road bike version at a price I'd be willing to pay I'd be
interested in something like this.

On training rides it would be a nice thing to have (and the increased weight
would be less of an issue) not least because current road bike rims get
buckled if you sneeze while riding on them (I exaggerate (slightly))

~~~
Kluny
I would like to put it on a trailer, so the trailer would bounce around less
behind you. One of these guys:
[http://travellingtwo.com/gallery2/d/44786-2/tombike.jpg](http://travellingtwo.com/gallery2/d/44786-2/tombike.jpg)

------
portlander12345
Is it just me, or has Wired completely failed to load on Mobile Safari for
months?

------
derekp7
Unless I missed it in the article, what's the advantage of this vs. mounting
the wheel on a regular spring/shock? Other than needing minimal modifications
to the base platform?

~~~
scelerat
That's a pretty big advantage already, if it's just a drop-in for existing
mounts.

~~~
toufka
Though 3 shocks per wheel hits a very different price-point than 2 shocks per
vehicle.

------
serf
as a wheelchair user:

looks heavy, and spoke wheels provide suspension.

also there are tons of wheels built from a similar premise in the past ;
they've all failed as long-lasting products.

------
sitkack
I love this design, it puts the complexity in a part that already is and
removes it from the frame. Lowering the total cost.

------
wazoox
There were elastic wheels 110 years ago:the "roue élastique Roussel" for cars.
it also inspired the lunar rover wheels back in appolo times. Hardly news.

------
adolph
How do you true those wheels?

~~~
freiheit
Low spoke count wheels, like these, have substantially more material in the
rim in order to make the rim stiff enough for the large gaps between spokes to
work at all.

All that's needed is for all three spokes to have equal tension (and no
excessive forces applied) and the wheel should stay true.

