JJP&E Through Axle Conversion Kit

On Mon, 14 Sep 2020 12:11:41 -0400,
Frank Krygowski wrote:
On 9/13/2020 9:54 PM, AMuzi wrote:
On 9/13/2020 8:23 PM, Frank Krygowski wrote:
On 9/13/2020 9:14 PM, AMuzi wrote:

...tandem bicycles, academic staff pensions...

Hey, tandem bicycles are a good topic for this group! Discuss
away!

Regarding academia, I'd prefer to discuss the value of
tenure. Spoiler: I'm against it, as it's currently
configured.

But we can discuss pensions too, as long as I don't have to
divulge too much personal information. (No, you can't have
the name of my first pet.)

I only mentioned them because you so frequently claim to live
outside normal economic phenomena. Tandems are a great
example, your typical quality tandem being $5000 to $12000
versus $500 for a department store 7 speed.

In 2020 dollars, our tandem cost about $3100. In those days
(the 1970s) a custom builder seemed the only way to get a
decent quality tandem. I purposely sought out a builder who
told me he would keep cost down by reducing the detail finish
work. For example, the chainstays are not beautifully sculpted
into the dropouts.

As I said, this tandem has proven to be one of the best
purchases we ever made - except for the disaster of the
severely weak front fork, previously described in detail. The
bike works very well.

Are there better ones? Yes, the technology was advancing pretty
rapidly when we bought this one. If we had waited maybe three
years, I imagine this one would have been built following
Santana's practice, and thus been rigid enough for me to pedal
while standing.

Like you, our tandem investments have been one of our best things
we ever spent money on--ballroom dance lessons being the other.

I do have to say I'd be really bummed about not being able to
pedal while standing on the tandem. We do that quite a lot, not
least to get up steeper hills without walking.

--
Ted Heise West Lafayette, IN, USA

On 9/14/2020 1:21 PM, Ted Heise wrote:
On Mon, 14 Sep 2020 12:11:41 -0400,
Frank Krygowski wrote:

In 2020 dollars, our tandem cost about $3100. In those days
(the 1970s) a custom builder seemed the only way to get a
decent quality tandem. I purposely sought out a builder who
told me he would keep cost down by reducing the detail finish
work. For example, the chainstays are not beautifully sculpted
into the dropouts.

As I said, this tandem has proven to be one of the best
purchases we ever made - except for the disaster of the
severely weak front fork, previously described in detail. The
bike works very well.

Are there better ones? Yes, the technology was advancing pretty
rapidly when we bought this one. If we had waited maybe three
years, I imagine this one would have been built following
Santana's practice, and thus been rigid enough for me to pedal
while standing.

Like you, our tandem investments have been one of our best things
we ever spent money on--ballroom dance lessons being the other.

I do have to say I'd be really bummed about not being able to
pedal while standing on the tandem. We do that quite a lot, not
least to get up steeper hills without walking.

Yeah, I do wish this bike had a more rigid frame. It has twin 1/2"
laterals (like mixte tubes) in addition to the "oversized" main frame
tubes, and its bottom brackets are linked by twin 1" "boob tubes." Soon
after it was built, Santana popularized a large central tube from
headset to rear bottom bracket, plus a large oval boob tube. IME that
design is much more rigid. In addition, I once modeled those changes to
this bike in Finite Element Analysis and confirmed they would make it
much more rigid.

My wife can stand to pedal, although she doesn't much like doing it. I
can't. The front end oscillates at maybe 4 or 5 Hz when I try.

We've had that same oscillation pedaling on fast downhills when doing
loaded touring, despite an only moderate load in rear panniers. If we
tour with this bike again, I'm going with most of the weight in front
low riders.

--
- Frank Krygowski

On Monday, September 14, 2020 at 12:18:45 PM UTC-7, Frank Krygowski wrote:
On 9/14/2020 1:21 PM, Ted Heise wrote:
On Mon, 14 Sep 2020 12:11:41 -0400,
Frank Krygowski wrote:

In 2020 dollars, our tandem cost about $3100. In those days
(the 1970s) a custom builder seemed the only way to get a
decent quality tandem. I purposely sought out a builder who
told me he would keep cost down by reducing the detail finish
work. For example, the chainstays are not beautifully sculpted
into the dropouts.

As I said, this tandem has proven to be one of the best
purchases we ever made - except for the disaster of the
severely weak front fork, previously described in detail. The
bike works very well.

Are there better ones? Yes, the technology was advancing pretty
rapidly when we bought this one. If we had waited maybe three
years, I imagine this one would have been built following
Santana's practice, and thus been rigid enough for me to pedal
while standing.

Like you, our tandem investments have been one of our best things
we ever spent money on--ballroom dance lessons being the other.

I do have to say I'd be really bummed about not being able to
pedal while standing on the tandem. We do that quite a lot, not
least to get up steeper hills without walking.

Yeah, I do wish this bike had a more rigid frame. It has twin 1/2"
laterals (like mixte tubes) in addition to the "oversized" main frame
tubes, and its bottom brackets are linked by twin 1" "boob tubes." Soon
after it was built, Santana popularized a large central tube from
headset to rear bottom bracket, plus a large oval boob tube. IME that
design is much more rigid. In addition, I once modeled those changes to
this bike in Finite Element Analysis and confirmed they would make it
much more rigid.

My wife can stand to pedal, although she doesn't much like doing it. I
can't. The front end oscillates at maybe 4 or 5 Hz when I try.

We've had that same oscillation pedaling on fast downhills when doing
loaded touring, despite an only moderate load in rear panniers. If we
tour with this bike again, I'm going with most of the weight in front
low riders.

An oscillation during out of the saddle climbing seems odd. Are your cranks in phase? Do you have a super-limber front end?

Our tandem was an early '90s Cannondale which was about as rigid as you could get for a tandem. Practically this exact bike (23/25): https://tinyurl.com/y2u9uq9u You can get these for a song, but forget about respacing. Those stays are not going anywhere. The Scott SE cantis were adequate but overheated the rims on long downhills. You could throw on a drag brake.

Thinking back, Di2/eTap and hydro discs would be awesome for a tandem -- with the right rotors. In any event, electronic would improve tandem shifting by a zillion percent. Put a shift button on the stoker bar and let him/her screw with you.

-- Jay Beattie.

On 9/14/2020 1:21 PM, jbeattie wrote:
On Monday, September 14, 2020 at 12:18:45 PM UTC-7, Frank Krygowski wrote:
On 9/14/2020 1:21 PM, Ted Heise wrote:
On Mon, 14 Sep 2020 12:11:41 -0400,
Frank Krygowski wrote:

In 2020 dollars, our tandem cost about $3100. In those days
(the 1970s) a custom builder seemed the only way to get a
decent quality tandem. I purposely sought out a builder who
told me he would keep cost down by reducing the detail finish
work. For example, the chainstays are not beautifully sculpted
into the dropouts.

As I said, this tandem has proven to be one of the best
purchases we ever made - except for the disaster of the
severely weak front fork, previously described in detail. The
bike works very well.

Are there better ones? Yes, the technology was advancing pretty
rapidly when we bought this one. If we had waited maybe three
years, I imagine this one would have been built following
Santana's practice, and thus been rigid enough for me to pedal
while standing.

Like you, our tandem investments have been one of our best things
we ever spent money on--ballroom dance lessons being the other.

I do have to say I'd be really bummed about not being able to
pedal while standing on the tandem. We do that quite a lot, not
least to get up steeper hills without walking.

Yeah, I do wish this bike had a more rigid frame. It has twin 1/2"
laterals (like mixte tubes) in addition to the "oversized" main frame
tubes, and its bottom brackets are linked by twin 1" "boob tubes." Soon
after it was built, Santana popularized a large central tube from
headset to rear bottom bracket, plus a large oval boob tube. IME that
design is much more rigid. In addition, I once modeled those changes to
this bike in Finite Element Analysis and confirmed they would make it
much more rigid.

My wife can stand to pedal, although she doesn't much like doing it. I
can't. The front end oscillates at maybe 4 or 5 Hz when I try.

We've had that same oscillation pedaling on fast downhills when doing
loaded touring, despite an only moderate load in rear panniers. If we
tour with this bike again, I'm going with most of the weight in front
low riders.

An oscillation during out of the saddle climbing seems odd. Are your cranks in phase? Do you have a super-limber front end?

Our tandem was an early '90s Cannondale which was about as rigid as you could get for a tandem. Practically this exact bike (23/25): https://tinyurl.com/y2u9uq9u You can get these for a song, but forget about respacing. Those stays are not going anywhere. The Scott SE cantis were adequate but overheated the rims on long downhills. You could throw on a drag brake.

Thinking back, Di2/eTap and hydro discs would be awesome for a tandem -- with the right rotors. In any event, electronic would improve tandem shifting by a zillion percent. Put a shift button on the stoker bar and let him/her screw with you.

-- Jay Beattie.

We could always climb out of saddle, without oscillation, on our tandem,
*except* when we put on full panniers and a handlebar bag. Large amount
of weight with a long moment arm, it was frightening to stand and pedal,
very hard to control. I remember that front low-rider panniers improved
stability as compared to a handlebar bag, don't recall if we could ride
out of the saddle (probably afraid to try).

PS - Our tandem has dual "lateral stays" from headtube to near rear
dropout. I was told they were made from Columbus seatstays (?like two
sets?), not sure if I believe that.

Mark J.

On 9/14/2020 5:25 PM, Mark J. wrote:
On 9/14/2020 1:21 PM, jbeattie wrote:
On Monday, September 14, 2020 at 12:18:45 PM UTC-7, Frank Krygowski
wrote:
On 9/14/2020 1:21 PM, Ted Heise wrote:
On Mon, 14 Sep 2020 12:11:41 -0400,
Â*Â*Â* Frank Krygowski wrote:
Â*Â* In 2020 dollars, our tandem cost about $3100. In those days
Â*Â* (the 1970s) a custom builder seemed the only way to get a
Â*Â* decent quality tandem. I purposely sought out a builder who
Â*Â* told me he would keep cost down by reducing the detail finish
Â*Â* work. For example, the chainstays are not beautifully sculpted
Â*Â* into the dropouts.

Â*Â* As I said, this tandem has proven to be one of the best
Â*Â* purchases we ever made - except for the disaster of the
Â*Â* severely weak front fork, previously described in detail. The
Â*Â* bike works very well.

Â*Â* Are there better ones? Yes, the technology was advancing pretty
Â*Â* rapidly when we bought this one. If we had waited maybe three
Â*Â* years, I imagine this one would have been built following
Â*Â* Santana's practice, and thus been rigid enough for me to pedal
Â*Â* while standing.

Like you, our tandem investments have been one of our best things
we ever spent money on--ballroom dance lessons being the other.

I do have to say I'd be really bummed about not being able to
pedal while standing on the tandem.Â* We do that quite a lot, not
least to get up steeper hills without walking.

Yeah, I do wish this bike had a more rigid frame. It has twin 1/2"
laterals (like mixte tubes) in addition to the "oversized" main frame
tubes, and its bottom brackets are linked by twin 1" "boob tubes." Soon
after it was built, Santana popularized a large central tube from
headset to rear bottom bracket, plus a large oval boob tube. IME that
design is much more rigid. In addition, I once modeled those changes to
this bike in Finite Element Analysis and confirmed they would make it
much more rigid.

My wife can stand to pedal, although she doesn't much like doing it. I
can't. The front end oscillates at maybe 4 or 5 Hz when I try.

We've had that same oscillation pedaling on fast downhills when doing
loaded touring, despite an only moderate load in rear panniers. If we
tour with this bike again, I'm going with most of the weight in front
low riders.

An oscillation during out of the saddle climbing seems odd. Are your
cranks in phase? Do you have a super-limber front end?

Well, the bike is fairly light for a tandem (something like 42 pounds
naked? I forget) so the oversized Reynolds 531 tubes probably have
fairly thin walls. The original fork was stupid light and failed. The
replacement came from Tandems Limited, whom I trust, and I think it's
stiff enough. The Tandems Ltd. proprietors are very knowledgeable.
(They reportedly advised my builder that his forks should be stronger.
Wish I knew that ahead of time.)

I'm pretty sure the oscillation is a twist around the long axis of the
frame. That's precisely the deflection that Santana's configuration and
that of your Cannondale was designed to prevent. With my twin laterals,
that deflection manifests as up and down bending of the thin tubes, and
they don't resist that well.


Our tandem was an early '90s Cannondale which was about as rigid as
you could get for a tandem. Practically this exact bike (23/25):
https://tinyurl.com/y2u9uq9uÂ* You can get these for a song, but forget
about respacing.

I've ridden one of those, as well as some Santanas. Yes, the Cannondale
is as rigid as can be.

Thinking back, Di2/eTap and hydro discs would be awesome for a tandem
-- with the right rotors.Â* In any event, electronic would improve
tandem shifting by a zillion percent. Put a shift button on the stoker
bar and let him/her screw with you.

:-) For all these years, I've kept secret from my stokers that they can
apply the rear brake by just pulling upward on the cable!

But this bike doesn't even have index shifting, yet shifts very well -
at least, by my standards. (Low standards are the key to happiness!)

We could always climb out of saddle, without oscillation, on our tandem,
*except* when we put on full panniers and a handlebar bag.Â* Large amount
of weight with a long moment arm, it was frightening to stand and pedal,
very hard to control.Â* I remember that front low-rider panniers improved
stability as compared to a handlebar bag, don't recall if we could ride
out of the saddle (probably afraid to try).

On one long tour, I found my heavily loaded handlebar bag caused my
Cannondale (single) touring bike to shimmy under certain conditions.
That bike is normally perfectly solid. The bag hung from its 1/4" wire
support, and I could see it swinging back and forth. I was able to cure
the problem by rearranging things, mostly moving the densest stuff
closer to the headset. Since then I built my own handlebar bag for that
bike and have had zero problems.

But I doubt that's the cause of the tandem's problem. The handlebar bag
on this bike is an old Cannondale bag. It's very firmly attached the the
handlebars and has a rigid plastic frame. Besides, it's not heavily loaded.

PS - Our tandem has dual "lateral stays" from headtube to near rear
dropout.Â* I was told they were made from Columbus seatstays (?like two
sets?), not sure if I believe that.

I agree. Those tubes would be an excellent place to use something like
generic 4130.


--
- Frank Krygowski

On Mon, 14 Sep 2020 15:18:37 -0400,
Frank Krygowski wrote:
On 9/14/2020 1:21 PM, Ted Heise wrote:
On Mon, 14 Sep 2020 12:11:41 -0400,
Frank Krygowski wrote:

Are there better ones? Yes, the technology was advancing
pretty rapidly when we bought this one. If we had waited
maybe three years, I imagine this one would have been built
following Santana's practice, and thus been rigid enough
for me to pedal while standing.

I do have to say I'd be really bummed about not being able to
pedal while standing on the tandem. We do that quite a lot,
not least to get up steeper hills without walking.

Yeah, I do wish this bike had a more rigid frame. It has twin
1/2" laterals (like mixte tubes) in addition to the "oversized"
main frame tubes, and its bottom brackets are linked by twin 1"
"boob tubes." Soon after it was built, Santana popularized a
large central tube from headset to rear bottom bracket, plus a
large oval boob tube. IME that design is much more rigid. In
addition, I once modeled those changes to this bike in Finite
Element Analysis and confirmed they would make it much more
rigid.

My wife can stand to pedal, although she doesn't much like
doing it. I can't. The front end oscillates at maybe 4 or 5 Hz
when I try.

Yow! Definitely sub-optimal.


We've had that same oscillation pedaling on fast downhills when
doing loaded touring, despite an only moderate load in rear
panniers. If we tour with this bike again, I'm going with most
of the weight in front low riders.

Never had the shimmy with either of our tandems, maybe because I'm
seldom allowed to go above 30 mph. Had the shimmy on an old
single at 50 mph one time, and just about crapped my shorts.

--
Ted Heise West Lafayette, IN, USA