mtb fork for solar car?

"Dave Mills" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

An engineering team here is considering building a
suspension system for a solar powered car using mountain
bike forks. Any recomendations on what might be good
choices to support approx. 180 lbs per shock? Would only
need to handle potholes in a road surface, but would be at
max. speed of 70mph and using high pressure tires. Good
adjustablity, damping, etc would be improtant, low weight
also desirable.

-DM

Do you want to use 2 mountain bike forks? Or build your own
linkage and use a rear shock on each corner? Marzocchi are
generally regarded as being the best MTB forks around. Some
of the better downhill forks perhaps, such as White Brothers
or the better Rock Shox downhill forks are also very good,
but with way too much travel for you I suspect. Standard cross-
country forks have about 80-110mm of travel. Downhill forks
have twice that. Most forks are designed for a 200lb rider
max, normal condition being 50/50 more or less regarding
weight distribution, so they are designed for approx 100lb
for setting up sag settings. They will take all 200lbs
without breaking obviously, but as far as optimum suspension
usage, you might be a little heavy on the fork. If it's a
180lb max load, you'd be fine.

Scott..

Dave Mills said:

An engineering team here is considering building a
suspension system for a solar powered car using mountain
bike forks. Any recomendations on what might be good
choices to support approx. 180 lbs per shock? Would only
need to handle potholes in a road surface, but would be at
max. speed of 70mph and using high pressure tires. Good
adjustablity, damping, etc would be improtant, low weight
also desirable.

Look into some of the Formula SAE cars, which are built by
engineering students, and run in autocross-type races. Your
application will be different, but the weight would be
similar. So you could probably do well by copying/adapting
one of those chassis. I know some Formula SAE cars have used
MTB shocks -- not forks, but rear ones.

Matt O.

Dave Mills said...

Quoted message said:

An engineering team here is considering building a
suspension system for a solar powered car using mountain
bike forks. Any recomendations on what might be good
choices to support approx. 180 lbs per shock? Would only
need to handle potholes in a road surface, but would be at
max. speed of 70mph and using high pressure tires. Good
adjustablity, damping, etc would be improtant, low weight
also desirable.

-DM

180lbs per shock is a lot of weight. The average rider
weighs about 180lbs, but that is distributed over two
wheels. You should be able to find something that works, but
you probably should consider only the most heavy duty
shocks, such as those designed for downhill and so- called
freeride use.

Dave Mills said:

An engineering team here is considering building a
suspension system for a solar powered car using mountain
bike forks. Any recomendations on what might be good
choices to support approx. 180 lbs per shock? Would only
need to handle potholes in a road surface, but would be at
max. speed of 70mph and using high pressure tires. Good
adjustablity, damping, etc would be improtant, low weight
also desirable.

-DM

Since solar power can only give you 1350 watts per square
meter are you sure you need something that heavy duty?

Unless you are planning on carrying heavy batteries and
spending 90% of the time charging them, any light weight
fork should work fine for a three wheel vehicle.

In article <[email hidden]>, Super Slinky

Quoted message said:

Quoted message said:

An engineering team here is considering building a
suspension system for a solar powered car using mountain
bike forks. Any recomendations on what might be good
choices to support approx. 180 lbs per shock? Would only
need to handle potholes in a road surface, but would be
at max. speed of 70mph and using high pressure tires.
Good adjustablity, damping, etc would be improtant, low
weight also desirable.

-DM

180lbs per shock is a lot of weight. The average rider
weighs about 180lbs, but that is distributed over two
wheels. You should be able to find something that works,
but you probably should consider only the most heavy duty
shocks, such as those designed for downhill and so- called
freeride use.

I recall the yearly solar powered car race ending up here
several years ago. I spoke to some of the people on the
teams and found that those using spoked wheels had a lot of
trouble with the wheels collapsing (and the wheels were
quite small, probably 20 inches or less). Therefore, I
suspect you will have failures in such a system.

Tom Gibb <[email hidden]

TBGibb said:

I recall the yearly solar powered car race ending up here
several years ago. I spoke to some of the people on the
teams and found that those using spoked wheels had a lot
of trouble with the wheels collapsing (and the wheels were
quite small, probably 20 inches or less). Therefore, I
suspect you will have failures in such a system.

I wonder if the wheels collapsed while cornering. 3 or 4
wheel vehicles weighing a few hundred pounds could put
significant lateral loads on their wheels, unlike a 2 wheel
vehicle. I've seen video of these sun racers cornering at
some pretty healthy speeds.

Matt O.

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

TBGibb said:

I recall the yearly solar powered car race ending up
here several years ago. I spoke to some of the people on
the teams and found that those using spoked wheels had a
lot of trouble with the wheels collapsing (and the
wheels were quite small, probably 20 inches or less).
Therefore, I suspect you will have failures in such a
system.

I wonder if the wheels collapsed while cornering. 3 or 4
wheel vehicles weighing a few hundred pounds could put
significant lateral loads on their wheels, unlike a 2
wheel vehicle. I've seen video of these sun racers
cornering at some pretty healthy speeds.

Matt O.

Good point and that could be an issue with bike forks as
well as wheels.

"Matt O'Toole" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

TBGibb said:

I recall the yearly solar powered car race ending up
here several years ago. I spoke to some of the people on
the teams and found that those using spoked wheels had a
lot of trouble with the wheels collapsing (and the
wheels were quite small, probably 20 inches or less).
Therefore, I suspect you will have failures in such a
system.

I wonder if the wheels collapsed while cornering. 3 or 4
wheel vehicles weighing a few hundred pounds could put
significant lateral loads on their wheels, unlike a 2
wheel vehicle. I've seen video of these sun racers
cornering at some pretty healthy speeds.

Matt O.

Greenspeed tandem trikes
(greenspeed.com.autandem.htmOpen ↗) usually carry multi-hundred-
pound loads- and they can corner briskly without
collapsing wheels.

(The staff photographer for the Solar Challenge 2001 owns a
Greenspeed tandem. Here's his site: tricolour.nettricolour.netOpen ↗ )

Back to the OP's question. Are you sure you want to use
conventional forks to support a vehicle that doesn't lean?
It seems to me that that's asking for trouble- your
structure will need to support the top of the fork and the
fork will need to be pretty rigid to avoid flexing in
corners. Both factors add weight.

You could do worse than knocking off Doug Malewicki's
California Commuter:
canosoarus.comCalCom01.htmOpen ↗ ,
including the wheels and front suspension.

Jeff

Dave Mills <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

An engineering team here is considering building a
suspension system for a solar powered car using mountain
bike forks. Any recomendations on what might be good
choices to support approx. 180 lbs per shock? Would only
need to handle potholes in a road surface, but would be at
max. speed of 70mph and using high pressure tires. Good
adjustablity, damping, etc would be improtant, low weight
also desirable.

At that weight per fork, you'll be wanting something
designed for tandems. There are a few suitable models
around, but they tend to be at the heavy and expensive end
of the market. Other posters have pointed out a few other
possible drawbacks, but if you want to pursue it further
then you could do worse than have a look at
www.mtbtandems.com and tell Alex I sent you.

James