Re: Are two bicycles necessary?

Johnny Sunset aka Tom Sherman said:

....This is the recumbent bike I would choose for touring:
-RANS Rocket- (and not just because I already
own one).

Certainly people do tour on the Rocket, but the weird back wheel scares
me. If the Sachs hub goes out on tour, how easy would it be to find
another replacement? Is the "typical" bike shop going to have one on
hand in that size? Probably not. ....This is my justification for
suggesting a 26/26 LWB bike that uses regular derailleurs. The more
common parts the recumbent has, the better.

(the Cycle Genius I suggested does use disk brakes, but those are pretty
common now on bike-store MTB's, which also use 26" wheels--and if a rim
goes out of true, you're more likely to be able to keep riding on it it
if you have disk brakes than calipers)

Quoted message said:

The RANS Rocket is also a very fun bike to ride, once the rider adapts
to the light control forces required.

I had a short wheelbase at first and didn't like it, mainly for one
reason--that it was fine on smooth clean pavement, but it did not handle
well in gravel and broken pavement at all. Normally you would not choose
to ride on gravelly or broken pavement of course, but during emergency
evasive maneuvers sometimes you end up taking a path that you wouldn't
choose otherwise. And it was at these exact moments that the SWB felt
its worst, as if it was going to slide sideways out from under me. The
LWB has this problem but it's much less severe.
~

DougC said:

Certainly people do tour on the Rocket, but the weird back wheel scares
me. If the Sachs hub goes out on tour, how easy would it be to find
another replacement?

It's a two edged sword: hub gears are intrinsically more reliable than
derailleurs so it's far less likely to go out in the first place. If
you're on tour and 20 miles from anywhere, how easy will it be to get
hold of a new derailleur? I think that's a lot more likely to happen
than a dead hub.

Quoted message said:

I had a short wheelbase at first and didn't like it, mainly for one
reason--that it was fine on smooth clean pavement, but it did not handle
well in gravel and broken pavement at all. Normally you would not choose
to ride on gravelly or broken pavement of course, but during emergency
evasive maneuvers sometimes you end up taking a path that you wouldn't
choose otherwise. And it was at these exact moments that the SWB felt
its worst, as if it was going to slide sideways out from under me. The
LWB has this problem but it's much less severe.

"SWB" and "LWB" don't tell you much on their own. You can have
implementations of either that will suck or blow on different terrains.
My SWB (HPVel Streetmachine GT) tourer is pretty much fine off the
pavement (it's done a few miles in its time fully loaded for touring on
unmade tracks), but I'd not be at all surprised to find SWBs that didn't
do so well.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email hidden] http://www.dundee.ac.uk/~pjclinch/

DougC said:

Johnny Sunset aka Tom Sherman said:

....This is the recumbent bike I would choose for touring:
-RANS Rocket- (and not just because I already
own one).

Certainly people do tour on the Rocket, but the weird back wheel scares
me. If the Sachs hub goes out on tour, how easy would it be to find
another replacement? Is the "typical" bike shop going to have one on
hand in that size? Probably not. ....This is my justification for
suggesting a 26/26 LWB bike that uses regular derailleurs. The more
common parts the recumbent has, the better.

The Rocket comes standard with a regular cassette hub - those with
Sachs 3x7 hubs or SRAM DualDrive were modified by a dealer or owner.

A RANS Rocket with a 47-406 rear tire, an 11-34 Shimano Megarange
cassette, and standard 52/42/30 "road" triple will have a gear range of
about 1.4 to 7.4 meters development (17 to 92 gear inches). This will
produce speeds from about 7½ to 40 kph (4½ to 25 mph) at a cadence of
90 rpm, which should be adequate for most touring use.

The ISO 406-mm rear wheel of the Rocket will be significantly stronger
than a larger wheel with the same number of spokes, which is also an
advantage in touring.

Quoted message said:

(the Cycle Genius I suggested does use disk brakes, but those are pretty
common now on bike-store MTB's, which also use 26" wheels--and if a rim
goes out of true, you're more likely to be able to keep riding on it it
if you have disk brakes than calipers)

Quoted message said:

The RANS Rocket is also a very fun bike to ride, once the rider adapts
to the light control forces required.

I had a short wheelbase at first and didn't like it, mainly for one
reason--that it was fine on smooth clean pavement, but it did not handle
well in gravel and broken pavement at all. Normally you would not choose
to ride on gravelly or broken pavement of course, but during emergency
evasive maneuvers sometimes you end up taking a path that you wouldn't
choose otherwise. And it was at these exact moments that the SWB felt
its worst, as if it was going to slide sideways out from under me. The
LWB has this problem but it's much less severe.

I would much rather ride a SWB on loose surfaces than a LWB. With an
approximate 40%/60% front/rear weight distribution, the Rocket's front
wheel is less likely to skid on loose surfaces, while still having an
effective rear brake. The inherent SWB advantage in low speed handling
can also be helpful on unimproved surfaces. The LWB will typically
ride better (especially a bike with some vertical compliance such as
the RANS Stratus).

--
Tom Sherman - Post Free or Die!

Johnny Sunset aka Tom Sherman said:

....
The Rocket comes standard with a regular cassette hub - those with
Sachs 3x7 hubs or SRAM DualDrive were modified by a dealer or owner.
....

Well nuts.
Both the Rockets I have seen (on opposite ends of the USA no less) had
geared hubs. -?- I assumed they came that way. Both people /were/
touring on them.

Quoted message said:

I would much rather ride a SWB on loose surfaces than a LWB. With an
approximate 40%/60% front/rear weight distribution, the Rocket's front
wheel is less likely to skid on loose surfaces, while still having an
effective rear brake. The inherent SWB advantage in low speed handling
can also be helpful on unimproved surfaces. The LWB will typically
ride better (especially a bike with some vertical compliance such as
the RANS Stratus).

On the LWB I have, the seat is adjusted almost all the way back and I
weigh 275 lbs, and the weight distribution on the rear is still only
about 66%. I calculated that (on this bike) to push the weight
distribution to 80% rear at my height (6'2"😉 I would need to weigh ~450
lbs.

As far as riding in gravel, I just advise people try it and see. A LWB
is more stable than a SWB for the same reason that drag racers and sand
rails are built long--simply the longer wheelbase.

The reason that front tires on bents slide is simple: in a misguided
effort to achieve minimal rolling resistance, people run tires too
narrow and inflated to a pressure that is too high. The front tire
should be inflated to a pressure (with respect to the rear tire) that is
no greater than the proportion of weight that it is carrying. On the LWB
above for instance--the rear tire is 100 PSI, the front tire is 45 PSI.
If there is a risk of damage from inflating a narrow front tire to a
lower pressure--then you simply need a wider tire in front.
~

DougC said:

As far as riding in gravel, I just advise people try it and see. A LWB
is more stable than a SWB for the same reason that drag racers and sand
rails are built long--simply the longer wheelbase.

One person's "more stable" is another's "less responsive". If I'm in
gravel and thing start to slide I think I'd sooner be on "more
responsive" but of course mileage varies.

Quoted message said:

The reason that front tires on bents slide is simple: in a misguided
effort to achieve minimal rolling resistance, people run tires too
narrow and inflated to a pressure that is too high. The front tire
should be inflated to a pressure (with respect to the rear tire) that is
no greater than the proportion of weight that it is carrying.

I'd have thought that the weight distribution will change dramatically
under heavy braking, which is one of the occasions you're likely to be
sliding the front wheel... It will also change when you're going up a
steep hill. Personally, ICBA to reinflate my tyres to different
pressures according to the slope I'm on or the braking effect!

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email hidden] http://www.dundee.ac.uk/~pjclinch/

DougC wrote:

:: The reason that front tires on bents slide is simple: in a misguided
:: effort to achieve minimal rolling resistance, people run tires too
:: narrow and inflated to a pressure that is too high. The front tire
:: should be inflated to a pressure (with respect to the rear tire)
:: that is no greater than the proportion of weight that it is
:: carrying. On the LWB above for instance--the rear tire is 100 PSI,
:: the front tire is 45 PSI. If there is a risk of damage from
:: inflating a narrow front tire to a lower pressure--then you simply
:: need a wider tire in front. ~

Really? You're saying that if I'm riding a 26/26 (SXP) with 100 PSI (max)
tires and I max the rear I should make the front at 45 PSI? What about
pinch flats and stuff? Would those mainly be limited to the rear tire?

Roger Zoul said:

Really? You're saying that if I'm riding a 26/26 (SXP) with 100 PSI (max)
tires and I max the rear I should make the front at 45 PSI? What about
pinch flats and stuff? Would those mainly be limited to the rear tire?

It depends on what the weight distribution of the particular bike/rider
combination is. Put the front tire on a bathroom scale, and sit on the
bike with your feet resting on the pedals and hold yourself up with a
hand against a wall. Then with the rider and bike total weights you can
figure it out.

The front tire should have /at/ /least/ the same contact patch are as
the rear, /if/ /not/ /more/. So for a bike that carries two-thirds of
its weight on the rear tire, then the front should be inflated to no
more than about one-half the pressure of the rear. If the weight
distribution was 40/60 F/R, then the front tire should be inflated to no
more than 2/3 the pressure of the rear. For a 45/55 F/R bike, the front
should be no more than about 80% of the rear pressure.

There will be no greater danger of a pinch flat in the lower-inflated
front tire because while the pressure is lower, the load on the tire is
lower as well. You are not "increasing" the risk of pinch flats as much
as you are equalizing it; if both were inflated to the same pressure but
the rear was carrying more weight, then the rear would be more at risk
for pinching. You are not saving much of anything by over-inflating the
front tire; the decrease in rolling resistance is minuscule. All it
really gets you is much worse steering response.

......If the thought of a front pinch flat concerns you and you decide to
run a wider front tire, then it should be at a pressure that is even
lower than the weight proportion. The front needs to be re-figured based
on the proportions of the wider front tire to the narrower rear.
[-I should probably put up a web page explaining all this-]

---------------

The problem I think is that people are used to upright bikes, that all
tend to hold very-close-to 50/50 weight distribution, so people inflate
both [recumbent] tires to the same PSI and forget about it. On a bike
with significantly-different front/rear weight distribution, inflating
both tires to the same pressure is simply not correct.
~

DougC said:

The front tire should have /at/ /least/ the same contact patch are as
the rear, /if/ /not/ /more/.

Why?

I've never worried about this on any bike I've ever had, and I don't
recall ever suffering as a result, so it comes over as rather more
grounded in theory than practice.

I don't see why the front tyre needs calibrating to the rear. It
doesn't know what pressure the rear is running at or what the contact
patch is: shirley whether it will skid or not is down to absolutes, not
values relative to the back?

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email hidden] http://www.dundee.ac.uk/~pjclinch/

DougC wrote:
:: Roger Zoul wrote:
:::
::: Really? You're saying that if I'm riding a 26/26 (SXP) with 100
::: PSI (max) tires and I max the rear I should make the front at 45
::: PSI? What about pinch flats and stuff? Would those mainly be
::: limited to the rear tire?
:::
:::
::
:: It depends on what the weight distribution of the particular
:: bike/rider combination is. Put the front tire on a bathroom scale,
:: and sit on the bike with your feet resting on the pedals and hold
:: yourself up with a hand against a wall. Then with the rider and bike
:: total weights you can figure it out.

I think having to figure weight distribution to ride is an rather extreme
thing to do.

::
:: The front tire should have /at/ /least/ the same contact patch are as
:: the rear, /if/ /not/ /more/. So for a bike that carries two-thirds of
:: its weight on the rear tire, then the front should be inflated to no
:: more than about one-half the pressure of the rear. If the weight
:: distribution was 40/60 F/R, then the front tire should be inflated
:: to no more than 2/3 the pressure of the rear. For a 45/55 F/R bike,
:: the front should be no more than about 80% of the rear pressure.
::
:: There will be no greater danger of a pinch flat in the lower-inflated
:: front tire because while the pressure is lower, the load on the tire
:: is lower as well.

What load? Loads can change based on what happens with road conditions, can
they not?

You are not "increasing" the risk of pinch flats
:: as much as you are equalizing it; if both were inflated to the same
:: pressure but the rear was carrying more weight, then the rear would
:: be more at risk for pinching. You are not saving much of anything by
:: over-inflating the front tire; the decrease in rolling resistance is
:: minuscule. All it really gets you is much worse steering response.

How did you arrive at this definition of overinflating? I think of
overinflating as going beyond rated max psi. Can you direct me to a cite
somewhere?

::
:: .....If the thought of a front pinch flat concerns you and you
:: decide to run a wider front tire, then it should be at a pressure
:: that is even lower than the weight proportion. The front needs to be
:: re-figured based on the proportions of the wider front tire to the
:: narrower rear. [-I should probably put up a web page explaining all
:: this-]

I'd love to see that. I don't want to seem as if I'm attacking you for
responding to my post. But I'm curious as to the basis for your statements.

::
:: ---------------
::
:: The problem I think is that people are used to upright bikes, that
:: all tend to hold very-close-to 50/50 weight distribution, so people
:: inflate both [recumbent] tires to the same PSI and forget about it.
:: On a bike with significantly-different front/rear weight
:: distribution, inflating both tires to the same pressure is simply
:: not correct. ~

I must agree with the other poster....why? Is there some reference for most
of these statements?

Quoted message said:

Quoted message said:

Quoted message said:

shirley whether it will skid or not is down to absolutes, not

values relative to the back?

Don't call me shirley

Peter Clinch said:

DougC said:

The front tire should have /at/ /least/ the same contact patch are as
the rear, /if/ /not/ /more/.

Why?

I've never worried about this on any bike I've ever had, and I don't
recall ever suffering as a result, so it comes over as rather more
grounded in theory than practice.

I don't see why the front tyre needs calibrating to the rear. It
doesn't know what pressure the rear is running at or what the contact
patch is: shirley whether it will skid or not is down to absolutes, not
values relative to the back?

Pete.

This is mainly a recumbent/"alternate"-bike issue, as these bicycles
tend to have wider differences in weight distribution than upright bikes
do, and riders cannot shift their weight significantly during riding.

The reason that this is important is because if you enter a low-traction
situation and one of your tires begins to slide, you want it to be the
rear to slide first rather than the front. The rear tire will follow the
front tire, even if the rear tire is sliding. On a sandy road surface,
you can slide short distances with the rear wheel locked up and keep the
bike upright fairly easily--but it is damn near impossible to slide more
than a few inches with the front tire locked up (on either road bikes or
recumbents). Because of the front tire starts to slide, you cannot steer
at all and you have a far greater chance of crashing.

So (on a two-wheeled vehicle that is not a Segway) the front tire should
-always- have more traction than the rear. That means since the front is
carrying less weight, you run a lower front pressure so that the contact
patch is at least as large as the rear is.

And if you're running narrow tires, you can see some significant
handling gains by switching to a wider front tire as well. Narrow tires
do not handle loose surfaces well.
~

DougC said:

Peter Clinch said:

DougC said:

The front tire should have /at/ /least/ the same contact patch are as
the rear, /if/ /not/ /more/.

Why?

I've never worried about this on any bike I've ever had, and I don't
recall ever suffering as a result, so it comes over as rather more
grounded in theory than practice.

I don't see why the front tyre needs calibrating to the rear. It
doesn't know what pressure the rear is running at or what the contact
patch is: shirley whether it will skid or not is down to absolutes, not
values relative to the back?

Pete.

This is mainly a recumbent/"alternate"-bike issue, as these bicycles
tend to have wider differences in weight distribution than upright bikes
do, and riders cannot shift their weight significantly during riding.

The reason that this is important is because if you enter a low-traction
situation and one of your tires begins to slide, you want it to be the
rear to slide first rather than the front. The rear tire will follow the
front tire, even if the rear tire is sliding. On a sandy road surface,
you can slide short distances with the rear wheel locked up and keep the
bike upright fairly easily--but it is damn near impossible to slide more
than a few inches with the front tire locked up (on either road bikes or
recumbents). Because of the front tire starts to slide, you cannot steer
at all and you have a far greater chance of crashing.

So (on a two-wheeled vehicle that is not a Segway) the front tire should
-always- have more traction than the rear. That means since the front is
carrying less weight, you run a lower front pressure so that the contact
patch is at least as large as the rear is.

And if you're running narrow tires, you can see some significant
handling gains by switching to a wider front tire as well. Narrow tires
do not handle loose surfaces well.

But since narrow tires are 100 psi and mtb 45-60 your saying just
change tires anyway.
Is that an adequate summary. I changed to narrow because less friction
and lighter tire will give you higher less cumbersome speed.

DougC said:

This is mainly a recumbent/"alternate"-bike issue, as these bicycles
tend to have wider differences in weight distribution than upright bikes
do, and riders cannot shift their weight significantly during riding.

But it's not a problem on my recumbent tourer either...

Quoted message said:

The reason that this is important is because if you enter a low-traction
situation and one of your tires begins to slide, you want it to be the
rear to slide first rather than the front.

Why? If it's a rear wheel drive bike (as most are) then you can't get
traction any more if the back is slipping. I've never seen any owners
of freight bikes (I have one for direct experience) fiddle about with
tyre pressures just because they've put 50 Kg load in the front/back
which changes the wheel loading.

Quoted message said:

The rear tire will follow the
front tire, even if the rear tire is sliding. On a sandy road surface,
you can slide short distances with the rear wheel locked up and keep the
bike upright fairly easily--but it is damn near impossible to slide more
than a few inches with the front tire locked up (on either road bikes or
recumbents). Because of the front tire starts to slide, you cannot steer
at all and you have a far greater chance of crashing.

I spend a fair bit of time on loose surfaces (my house is on an unmade
track), and most times I've ever come off have been when I've lost all
traction at the back, ground to a halt with no effective power and
toppled over sideways. I've also come off with the back sliding out on
me on gravel.

The only time I've locked up the front wheel is under heavy emergency
braking and I've just slid forwards. Since the front suspension dived
it's fair to say far more weight than the usual riding weight was on the
front wheel, and it skidded anyway because of brake lock, not tyre pressure.

Quoted message said:

So (on a two-wheeled vehicle that is not a Segway) the front tire should
-always- have more traction than the rear. That means since the front is
carrying less weight, you run a lower front pressure so that the contact
patch is at least as large as the rear is.

But I don't, /and it isn't a problem/, and nobody else I know aside from
you does, /and they don't have problems either/. So I look at the
empirical data and it doesn't stack up for this being in any way important.

Quoted message said:

And if you're running narrow tires, you can see some significant
handling gains by switching to a wider front tire as well. Narrow tires
do not handle loose surfaces well.

That's quite true, but as I run 38mm Marathons it's not something I feel
a need to change.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email hidden] http://www.dundee.ac.uk/~pjclinch/

I mainly stick to riding the one trike for all my needs

Sliding etc.. being less of an issue on three wheels and I find that rough/loose ground is little of an issue, although I get no ejoyment from "hacking" through mud and stuff so generally avoid such conditions anyway.

I do have a folding Dahon hybrid type bike with 26" whhels however for when I travel by train as I can take it with me easier that a trike and still enjoy a cycle around London, it is damned uncomfortable after the hammock seat of the trike however so I use it very little, still it's nice to have the option.
--

Buck

I would rather be out on my Catrike

http://www.catrike.co.uk