Hopping on a Schwinn

A recent thread warned of damage that could be done by hopping on the older untempered Schwinn axles.

Despite this and because I recently put a Primo tire on my Schwinn I decided to try a bit of light hopping.

Turns out hopping is much easier with this tire than the original Schwinn tire and, perhaps due to the current pressure which is very slightly squishy, I can hop higher.

Does the fact that the tire is squishy and seems to absorb the bouncing better minimize the risk of damage to the axle? I’m looking for any excuse to work on this skill despite the aforementioned warning as I’d like to get to the point where I can hop up curbs.

Many thanks,
Raphael Lasar
Matawan, NJ

Re: Hopping on a Schwinn

I have owned several Schwinns over the years. I’ve never bent or broken an
axle from hopping or jumping (with one exception). I routinely hopped up
and down curbs and steps. I periodically did drops of over 1 foot. The one
time I bent cranks was during a club performance at the local University
(BYU). I rode off the edge of the stage to the floor (about a 3’ drop) and
landed it poorly. The only visible damage was a bent crank. I’m not as
aggressive as many but I haven’t had any significant problems with bending
or breaking stuff (even on the really cheap stuff).

A lot depends on your weight too (I’m about 180lbs.) I know someone (I
won’t name names) who can bend Schwinn cranks just by mounting and doing
small hops.

If you find that you do bend or break the cranks/hub you can get inexpensive
replacements (of course the inexpensive stuff will still be susceptible to
the same problems).

-mg

“JJuggle” <JJuggle.e26oy@timelimit.unicyclist.com> wrote in message
news:JJuggle.e26oy@timelimit.unicyclist.com
>
> A recent thread warned of damage that could be done by hopping on the
> older untempered Schwinn axles.
>
> Despite this and because I recently put a Primo tire on my Schwinn I
> decided to try a bit of light hopping.
>
> Turns out hopping is much easier with this tire than the original
> Schwinn tire and, perhaps due to the current pressure which is very
> slightly squishy, I can hop higher.
>
> Does the fact that the tire is squishy and seems to absorb the bouncing
> better minimize the risk of damage to the axle? I’m looking for any
> excuse to work on this skill despite the aforementioned warning as I’d
> like to get to the point where I can hop up curbs.
>
> Many thanks,
> Raphael Lasar
> Matawan, NJ
>
>
> –
> JJuggle - I (heart) Squirrels
>
> I’ve clowned around much too much to be considered hard working. - RL
>
> I feel sorry for humans, they have to work like hell to be successful.
> I can make the audience go wild just by taking my jacket off at the
> right moment.
> - Goscha, the monkey, quoted in Kaskade No 68, pg 30
> ------------------------------------------------------------------------
> JJuggle’s Profile: http://www.unicyclist.com/profile/24
> View this thread: http://www.unicyclist.com/thread/21633
>

Re: Hopping on a Schwinn

Why only Schwinn axles? There was nevery anything especially weak about the Schwinns. Any untempered axle is going to tend to be weaker than a tempered one. I’m not sure which brands have which, especially in “legacy” models.

I learned on a (cottered) Schwinn, and believe me we used to beat on them a lot. I didn’t start breaking axles regularly until much later, when I started doing a lot more hopping and other high-stress tricks. But I did plenty of it in my early days, including learning to hop.

I would say that it lowers it, but doesn’t minimize it. Make sure your rim isn’t hitting the ground, of course. Go ahead and hop. If you axle breaks, it breaks. This is unlikely to happen until after many thousands of hops & small drops.

In fact, I had an experience that parallels Michael Grant’s. In one of my very earliest shows ever, I jumped off the stage at the local community college I was attending at the time. It was about 3’, and I landed seemingly almost all on one pedal. This ended me up with a bent crank, but a still rideable unicycle. Don’t remember if this was my old Schwinn or Miyata.

Re: Hopping on a Schwinn

Thanks both for your comments. Looks like:

Hopping days are here again!

Raphael Lasar
Matawan, NJ

i don’t realy worry about the stress on the unicycle if it has a non splined unless i drop more than a foot.

Re: Re: Hopping on a Schwinn

I bet that person was highly intelligent, good looking…and humble. :smiley:

I just learnt this the other day in physics:
The force acting on a unicycle is proportional to the displacement in stopping it. If you use a bigger tyre then you can use a lower pressure which will allow it to ‘squish’ down furthur when you land. Although there may be other more important factors like landing technique and so on, I’m pretty sure that having a bigger tyre with lower pressure will make a difference.

Having said all this, you may not want to believe me because when I tried to work out the force acting on a frame with no flex of the knees and with me (65kg) on the unicycle, I got 60000 - 80000 Newtons:) . This is roughly the force of a mass of 6100 - 8200 kg!

It took drops of about 70cm onto grass to bend my cranks and hub but I’m pretty light. This was landing onto grass. This unicycle that I’m talking about is a really cheap one too. It was $200 Australian (about $2 US).

My new unicycle’s going to be a beast!

Andrew

Re: Re: Re: Hopping on a Schwinn

Indeed he was (is). Why? Do you know him? :slight_smile:

-mg

Re: Hopping on a Schwinn

On Wed, 13 Nov 2002 23:17:34 -0600, yoopers
<yoopers.e3efy@timelimit.unicyclist.com> wrote:

>I bet that person was highly intelligent, good looking…and humble.
No it wasn’t me.

Klaas Bil

More than half of the 535 first-year teachers in the Dallas School District (8th largest district in the country at the time) flunked a mental aptitude test in 1979. The test was normally given to 13-year-olds.

Re: Hopping on a Schwinn

On Thu, 14 Nov 2002 00:01:36 -0600, andrew_carter
<andrew_carter.e3giz@timelimit.unicyclist.com> wrote:

>
>I just learnt this the other day in physics:
>The force applied to the unicycle is proportional to the displacement in
>stopping it. <SNIP>
>Having said all this, you may not want to believe me because when I
>tried to work out the force acting on a frame with no flex of the knees
>and with me (65kg) on the unicycle, I got 60000 - 80000 Newtons:) .
>This is roughly the force of a mass of 6100 - 8200 kg!

The following works if you assume uniform deceleration when landing a
drop. The force that the unicycle exerts on the contact point is the
ratio of drop height over the displacement in stopping it, multiplied
by the weight of rider and unicycle. So in your case, if you drop 70
cm, and decelerate over a distance of 5 cm (ratio of 14), and you and
the unicycle weigh 75 kg, then the uni pushed into the ground with a
force as if had a static weight of (14 x 75 =) 1050 kg (about 10500
Newtons). In real life, the force on the frame would be less than
that, if only because part of the force is going through your legs
rather than the frame.

Since the deceleration process is complicated (part seat, party tyre,
part legs, not all simultaneous, roll-out etc) the above is a first
approximation only.

Klaas Bil

Growing enough wheat for a 1-pound loaf of bread requires 2 tons of water.

Re: Re: Hopping on a Schwinn

How did the 13-year-olds do?

a true psysics student/teacher/forum reader knows that there is no such thing as deceleration, but only negative acceleration.:smiley:

I busted a Schwinn hub trying to hop on it with a hard tire. I weigh 175 pounds. Not Kilograms. carjug

I went off a 2.5 foot drop on my Schwinn and the one crank was bent so they are no longer 180 degrees (about 160 degrees on one side) but I still ride it and practice wheel walking, etc. :smiley:

Re: Hopping on a Schwinn

On Thu, 14 Nov 2002 18:02:50 -0600, johnfoss
<johnfoss.e4uiz@timelimit.unicyclist.com> wrote:

> How did the 13-year-olds do?
No idea. I borrowed the quote from Gluteous Maximus who posted a whole
bunch on Just Conversation (from a source not disclosed).

Klaas Bil

"There are more than one thousand chemicals in a cup of coffee. Of these, only 26 have been tested, and have caused cancer in rats. "

whats all this about dropping and breaking stuff? i weigh 110 lbs and i can do 3 foot drops and not break anything on my cheap little $140 CDN uni. ive never come close to breaking anything. i never measured any of the force and stuff, but i weigh 110 lbs and my uni is a 20" wheel and frame, with a 28-spoke wheel. I use a 2.125" wide tire as well. the wider tire makes it feel a lot smoother on the landing. well thats about it. so there. modern technology or something…

the problem is the tempering of the hubs - I remember someone telling me (I could easily be wrong here) that some of the hubs were untempered (not hardened) but that they have gone back to tempering them now.

Re: Hopping on a Schwinn

unisteve wrote:
> what’s all this about dropping and breaking stuff? i weigh 110 lbs
> and i can do 3 foot drops and not break anything on my cheap little
> $140 CDN uni. I’ve never come close to breaking anything. i never
> measured any of the force and stuff, but i weigh 110 lbs and my uni
> is a 20" wheel and frame, with a 28-spoke wheel. I use a 2.125" wide
> tire as well. the wider tire makes it feel a lot smoother on the
> landing. well that’s about it. so there. modern technology or
> something…

I have dumbbells heavier than you.

110#, sheesh.


I unicycled to the State Fair just a few blocks from work. All the
suits and skirts mosey down out of the office buildings for lunch to
get some of that wholesome fair fare. As I passed a couple of skirts,
one says to the other, ‘Dork.’ The other cut sultry eyes in my
direction and said, ‘Ya? I gotta get me some Dork, then.’
–Christopher Rhysling