TDF climbers

Jon Senior said:

Arthur Clune [email hidden] opined the following...

Quoted message said:

For short climbs, leave it in a big gear, get out of the saddle and
blast over. Start with railway bridges and work up.

Feels good, doesn't it?

Jon

Yes :-) I can do this on some ickle hills now, and it's an amazing
feeling! Of course, when I get it wrong and misjudge the hill, ooooh
you pay for it.... and for quite a while after, too!

Priceless moment though is clicking up a couple of gears, whooshing past
your fitter leaner faster other half and charging up the hill to leave
him behind and with a suprised look on his face... just a shame I can't
do it on *all* the hills yet ;-)

Spinning up them in my lowest gear at the limit of what my legs can do
gets boring after a while...

--

Velvet

Velvet typed:

Quoted message said:

Spinning up them in my lowest gear at the limit of what my legs can do
gets boring after a while...

.... but is effective and _will_ benefit you in the long run .. 😉

--
Paul ...

(8(|) ... Homer Rocks

Jon Senior said:

Cast iron jigs it is! (Sort of) I plan to cut a rectangle slightly
larger than the size I want. This will be soaked in warm water
overnight (This is easier to arrange than steaming!) then either
moulded with a
male / female MDF mould (Two identical moulds about 20mm thick should
suffice) and clamped, or screwed onto a steel frame to hold the shape.
When the wood has dried, I will attach a pair of "ribs" to the back of
it to strengthen it.

Good luck. I expect either you get unbent wet wood or the glue holding the
plys together disolves.

Quoted message said:

Cast iron jigs it is! (Sort of) I plan to cut a rectangle slightly
larger than the size I want. This will be soaked in warm water overnight
(This is easier to arrange than steaming!) then either moulded with a
male / female MDF mould (Two identical moulds about 20mm thick should
suffice) and clamped, or screwed onto a steel frame to hold the shape.
When the wood has dried, I will attach a pair of "ribs" to the back of
it to strengthen it.

I was considering laminating "bending plywood" but our local wood
stockist charges £33 + VAT for a sheet. Apparently, two layers of this
laminated makes a very good seat.

Given the performance of my current seat (Bends under load above the
back support) I've come to the conclusion that the ribs are essential.

I did see a very cool plan for using 1.5mm Aluminium to make a seat
(Also ribbed) which looks quite classy, but may well be a little
uncomfortable. Besides which a smaller (1200mm x 800mm) sheet of
galvanised Aluminium was priced about the same as the full sheet of
bendy board! Maybe if I ever build a low-racer, I'll consider it.

I hoping to attack the seat problem over the weekend or next week and
will of course keep you all informed.

Thanks for that, look forward to seeing/hearing the results.

Garry

in message <[email hidden]>, Jon Senior

jon_AT_restlesslemon_DOTco_DOT_uk ('') said:

garryb59 [email hidden] opined the following...

Quoted message said:

Quoted message said:

> The bent is currently undergoing another modification. I have an
> extra set of bar ends which I plan to use to bring the bars
> further back. This will be combined with a new seat (When I buy
> the sheet of 4mm ply and start bending wood!) to hopefully
> increase both comfort and aerodynamics.
>
> I have noticed high speed drag (>25mph) which I can only attribute
> to the relatively upright position of the seat. I'm hoping that if
> I can eliminate this I'll manage to exceed 40mph on the bent.
>
> Jon

You'll find it hard to bend 4mm ply. Better off getting several
pieces of thinner, say 1mm that will bend then laminating them over
a former to the required shape.

This caught my eye too. I've been wondering how I'm going to sort out
a seat for my home made bent for a while, and have come to the
conclusion that a basic ply frame[two bits and a hindge!] is going
to be the easiest way to go initially. Then Jon starts talking about
bending 4mm ply....I can only visualize cast-iron jigs and clamps
right now :-)

Spill them beans!

Cast iron jigs it is! (Sort of) I plan to cut a rectangle slightly
larger than the size I want. This will be soaked in warm water
overnight

Nononononononono don't do this. Not with plywood. You'll bugger it
utterly. Not even BS1088 will stand that treatment. Go into a model or
craft shop and get some birch ply in 1mm or 1.5mm, three times as much
as you need, and then epoxy it up in a jig to the curvature you want.
Or, better still, make yourself a male mould (out of more or less
anything) and shove some carbon fibre and epoxy at it.

Quoted message said:

I was considering laminating "bending plywood" but our local wood
stockist charges £33 + VAT for a sheet. Apparently, two layers of this
laminated makes a very good seat.

It's good stuff and would do but as you say expensive.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; single speed mountain bikes: for people who cycle on flat mountains.

MSeries [email hidden] opined the following...

Quoted message said:

Good luck. I expect either you get unbent wet wood or the glue holding the
plys together disolves.

A colleague used to use a similar technique to make the baffles for P.A.
speakers.

Take sheet of 4mm ply. Leave in a water tank overnight. In the morning,
bend to required angle and fix (They used a jig) and wait until it
dries.

By using warm water and a long period, rather than a short burst of
steam, you are less likely to do anything odd to the glues.

Should have mentioned. The plywood in question is marine ply. Thus
vaguely suited to watery situations.

Jon

Simon Brooke [email hidden] opined the following...

Quoted message said:

Nononononononono don't do this. Not with plywood. You'll bugger it
utterly. Not even BS1088 will stand that treatment. Go into a model or
craft shop and get some birch ply in 1mm or 1.5mm, three times as much
as you need, and then epoxy it up in a jig to the curvature you want.
Or, better still, make yourself a male mould (out of more or less
anything) and shove some carbon fibre and epoxy at it.

The laminated ply was my first plan of attack, but it is remarkably hard
to locate (It would seem!). I'll phone around the wood suppliers
tomorrow to see what I can arrange.

Would BS1088 be "marine ply"? This technique is reported as tried-and-
tested by a number of sources.

Quoted message said:

It's good stuff and would do but as you say expensive.

If I was sure of the success, I'd buy a sheet and make a few seats. One
sheet would cover me for future projects and would provide a few for
sale (I reckon that I could get about 5 seats at 2 ply out of a single
sheet!).

If you are confident that this would do the trick, I might be persuaded.
I can buy it on the company account and thus defer payment for a month.

With regard to laminating glues, any recommendations? I've heard PVA (?)
wood glue mentioned, along with epoxy. Epoxy would probably be easier to
"tune" the cure time to allow me to do this.

Jon

Paul - censored said:

Velvet typed:

Quoted message said:

Spinning up them in my lowest gear at the limit of what my legs can do
gets boring after a while...

... but is effective and _will_ benefit you in the long run .. 😉

Oh yes I know :-) It's the *only* way I can get up anything more than a
mere 'undulation' to most of you :-)

Spinning's not really an accurate term though, in my lowest gear it's
still more grinding than spinning, though that's improving *grin* - my
spinning muscles seem to be playing catch-up to the brute-force ones,
but brute-force is a very short-term unsustainable thing.

Tromping up the gentle short undulations is great fun though, makes me
feel good about cycling, and as long as I don't let the rpm drop (and
thus overstrain my slightly dodgy knees) it means I reap the benefits
when accelerating onto/around roundabouts these days!

--

Velvet

Jon Senior said:

With regard to laminating glues, any recommendations? I've heard PVA
(?) wood glue mentioned, along with epoxy. Epoxy would probably be
easier to "tune" the cure time to allow me to do this.

I would use PVA, cheap and you get plenty of working time. It has been OK
for my small laminating jobs. You may want waterproof PVA. My Dad used to
use some powdered glue on his model yachts, it was called Cascamite. Mixed
with water it really is waterproof when set.

On 15 Jul 2004 10:45:02 GMT, "Arthur Clune" <[email hidden]> wrote
in message <[email hidden]>:

Quoted message said:

: Interesting. I shall cut this out and keep it, as inability to pull on the
: bars is often cited as one of the reasons why "recumbents can't climb".

Quoted message said:

It's not about pulling up on the bars, its the inability to get out of the
saddle. That and the weight.

Ah, right. And getting out of the saddle allows you to put more force
on the pedals than your own weight, does it? ;-)

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

in message <[email hidden]>, Jon Senior

jon_AT_restlesslemon_DOTco_DOT_uk ('') said:

Simon Brooke [email hidden] opined the following...

Quoted message said:

Nononononononono don't do this. Not with plywood. You'll bugger it
utterly. Not even BS1088 will stand that treatment. Go into a model
or craft shop and get some birch ply in 1mm or 1.5mm, three times as
much as you need, and then epoxy it up in a jig to the curvature you
want. Or, better still, make yourself a male mould (out of more or
less anything) and shove some carbon fibre and epoxy at it.

The laminated ply was my first plan of attack, but it is remarkably
hard to locate (It would seem!). I'll phone around the wood suppliers
tomorrow to see what I can arrange.

Would BS1088 be "marine ply"? This technique is reported as tried-and-
tested by a number of sources.

BS1088 is indeed 'marine ply', although good marine ply is considerably
better (and more expensive) than the cheapest BS1088. There is (or used
to be) a little timber-merchant-come-picture-framers sort of shop round
the back of the Art College, sort of on the way from the Grassmarket to
Tollcross, which sold birch ply - Lawsons, I think. Try them if they're
still there.

Quoted message said:

Quoted message said:

It's good stuff and would do but as you say expensive.

If I was sure of the success, I'd buy a sheet and make a few seats.
One sheet would cover me for future projects and would provide a few
for sale (I reckon that I could get about 5 seats at 2 ply out of a
single sheet!).

If you are confident that this would do the trick, I might be
persuaded. I can buy it on the company account and thus defer payment
for a month.

Robbins of Bristol (who I've talked to about tortured ply structures)
reckon their 6mm bending ply can be safely bent dry to 150mm radius,
which is pretty impressive.

Quoted message said:

With regard to laminating glues, any recommendations? I've heard PVA
(?) wood glue mentioned, along with epoxy. Epoxy would probably be
easier to "tune" the cure time to allow me to do this.

Don't use PVA for something as structural as this. You don't want it to
delaminate. You can get boatbuilding epoxies in quite small packs from
yacht chandlers or from <URL:http://www.epoxy-resins.co.uk/>, or you
*could* use a lot of araldite (but it would end up being a lot more
expensive). Mind you wear rubber gloves or a very thorough application
of barrier cream when handling epoxy - some people develop sensitivity
to it, and then can't handle it again without getting horrible
dermatitis.

A moulded seat in GRP or carbon fibre might quite seriously be easier
and more successful, though.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/
;; If God does not write LISP, God writes some code so similar to
;; LISP as to make no difference.

Simon Brooke [email hidden] opined the following...

Quoted message said:

BS1088 is indeed 'marine ply', although good marine ply is considerably
better (and more expensive) than the cheapest BS1088. There is (or used
to be) a little timber-merchant-come-picture-framers sort of shop round
the back of the Art College, sort of on the way from the Grassmarket to
Tollcross, which sold birch ply - Lawsons, I think. Try them if they're
still there.

Lawsons is on my list of places to visit when I get a chance. Probably
on Saturday.

Quoted message said:

Robbins of Bristol (who I've talked to about tortured ply structures)
reckon their 6mm bending ply can be safely bent dry to 150mm radius,
which is pretty impressive.

Ply does seem better than it first appears, but my brief experiences
with bending it so far involved tortuous cracking noises.

Quoted message said:

Don't use PVA for something as structural as this. You don't want it to
delaminate. You can get boatbuilding epoxies in quite small packs from
yacht chandlers or from <URL:http://www.epoxy-resins.co.uk/>, or you
*could* use a lot of araldite (but it would end up being a lot more
expensive). Mind you wear rubber gloves or a very thorough application
of barrier cream when handling epoxy - some people develop sensitivity
to it, and then can't handle it again without getting horrible
dermatitis.

Thanks for the advice.

Quoted message said:

A moulded seat in GRP or carbon fibre might quite seriously be easier
and more successful, though.

Not sure about that. The initial mould may well cause me problems and
while I've a limited experience of working with wood, GRP & carbon fibre
are wholly new technologies to me. I do quite fancy the idea of a carbon
fibre seat but the experimentation leading up to it would (I suspect)
prove somewhat expensive.

Jon

Just zis Guy, you know? <[email hidden]> wrote:
: On 15 Jul 2004 10:45:02 GMT, "Arthur Clune" <[email hidden]> wrote

:>It's not about pulling up on the bars, its the inability to get out of the
:>saddle. That and the weight.

: Ah, right. And getting out of the saddle allows you to put more force
: on the pedals than your own weight, does it? ;-)

You know the score Guy so I won't rise to the bait......

--
Arthur Clune http://www.clune.org
"Technolibertarians make a philosophy out of a personality defect"
- Paulina Borsook