Shorter cranks on Double Vision

[Perry]

I did a Google search to see if any new pertinent information had come to light lately. All that
popped up were posts of mine, expounding the gloriousness of shorter cranks. I am at least a year
into using shorter cranks (165's) and I positively have no knee pain on my single bike. The tandem
(Double Vision) has 175's and my knee always hurts when we ride
it.Any new ideas on shortening cranks on the DV? I called Vision and Ricky Comar said it would cost
about $15,000. Machining, R& D, prototypes, etc. (I have heard that Ricky Comar is not at Vision
anymore...) Perry bentcajungirl down to just a Double Vision New R-40 Husband's R-44 and still
the El Camino.

 

[Guess Who I Am]

Hello: if you donot have IPS or splined crank i know of a machine shop that will drill and tap them
out for you. if intrested please e-mail me back. Thank you Earl GRR,RANS V2 Ti Rush,Ti Pursuit

 

[Perry]

Hi Earl, I do have IPS. (and I believe they're tapered) Why does that make a difference? Perry

"Guess Who I Am" <[email protected]> wrote in message
news:[email protected]...
> Hello: if you donot have IPS or splined crank i know of a machine shop that will
drill
> and tap them out for you. if intrested please e-mail me back. Thank you Earl GRR,RANS V2 Ti
> Rush,Ti Pursuit

 

[Don]

Perry, I do not know if the DV is something unique or just uses regular tandem components.
Maybe what I am posting is useless to you. But hopefully it is not. St. John Street Cycles.
http://www.sjscycles.com/store/vIndex.htm has beautiful Thorn cranks for front and rear
tandems 140-175mm

In the index do NOT look under cranksets. Look under "Chainsets" then "Tandem chainsets/cranks". I
have a triple solo from them in 150mm and it is very nicely done. I picked the TA rings. Their
polish matches the crank and they are ramped and pinned. Note which are marked outer, middle, and
inner. Please note on pricing, US customers do not have to pay the value added tax so the listed
price must be reduced by that amount. Also, when I ordered the arms, rings, and bolts I was promptly
informed that what I ordered was considered a kit so they assembled it for me and greatly reduced
the price. Delivered to my door in Sacramento from Jolly Olde in 9 days from my order. Nice chaps to
deal with. Spot on and all that rot. Good luck. Don

 

[Jeff Wills]

"Perry" <[email protected]> wrote in message
news:<[email protected]>... <snip>
> Any new ideas on shortening cranks on the DV? I called Vision and Ricky Comar said it would cost
> about $15,000. Machining, R& D, prototypes, etc. (I have heard that Ricky Comar is not at Vision
> anymore...)

Yeah, Ricky left a couple months back.

Regarding the cranksets: the IPS system required some special machining to accomodate the freewheel
mechanism. A really good machinist might be able to set up shorter cranks for IPS- but it's fairly
sensitive. You might want to talk to someone familiar with machining and bicycles... perhaps
Longbikes or Terracycle.

OTOH- ask yourself how often you use the IPS system. If you think you can get away with captain-only
freewheeling (that is, the captain could coast on his own, but the stoker would be forced to pedal
when the captain pedaled) then you could replace the stoker cranks with standard, but shorter
cranks. That's certainly the least expensive proposition.

Jeff

 

[Perry]

Thanks, Don. I just emailed them. Perry "Don" <[email protected]> wrote in message
news:[email protected]...
> Perry, I do not know if the DV is something unique or just uses regular tandem components. Maybe
> what I am posting is useless to you. But hopefully it is not. St. John Street Cycles.
> http://www.sjscycles.com/store/vIndex.htm has beautiful Thorn cranks for front and rear tandems
> 140-175mm
>
> In the index do NOT look under cranksets. Look under "Chainsets" then "Tandem chainsets/cranks". I
> have a triple solo from them in 150mm and it is very nicely done. I picked the TA rings. Their
> polish matches the crank and they are ramped and pinned. Note which are marked outer, middle, and
> inner. Please note on pricing, US customers do not have to pay the value added tax so the listed
> price must be reduced by that amount. Also, when I ordered the arms, rings, and bolts I was
> promptly informed that what I ordered was considered a kit so they assembled it for me and greatly
> reduced the price. Delivered to my door in Sacramento from Jolly Olde in 9 days from my order.
> Nice chaps to deal with. Spot on and all that rot. Good luck. Don

 

[Prints]

I run 145mm cranks on my trike and I'm a convert. Stopped my knee pain. Smoother and higher cadence.
If it's all in the mind, it worked for me.

MR now supply 155mm cranks on their Swiftlet S2.

Paul W

 

[Perry]

There is positively NO WAY I will ever give up IPS. Not until they pry my cold dead toes from my
Frogs. With a big battleship hulking bike like the Double Vision, there are just too many needs for
the IPS. Perry "Prints" <[email protected]> wrote in message
news:[email protected]...
> I run 145mm cranks on my trike and I'm a convert. Stopped my knee pain. Smoother and higher
> cadence. If it's all in the mind, it worked for me.
>
> MR now supply 155mm cranks on their Swiftlet S2.
>
> Paul W
>
>
>

 

[Steve Christens]

In article <[email protected]>, Perry says...
>
>There is positively NO WAY I will ever give up IPS. Not until they pry my cold dead toes from
>my Frogs.

What a GREAT line to be overheard by somone who has no knowledge of cycling.

"Just what were your toes doing on your Frogs?"

Steve Christensen

 

[Jeff Wills]

"Perry" <[email protected]> wrote in message
news:<[email protected]>...
> There is positively NO WAY I will ever give up IPS. Not until they pry my cold dead toes from my
> Frogs. With a big battleship hulking bike like the Double Vision, there are just too many needs
> for the IPS. Perry

)

If you're not going to give up IPS, then drilling and tapping the cranks is just about your only
choice. It'll still require a good machinist to do the deed, but it's not terrible complex.

They'll need to be shortened quite a bit, though, since enough material needs to be left on the
outside of the pedal eye to keep them from cracking. You'll probably end up with 145mm or 150mm
cranks, kind of like these cranks from DaVinci Designs: http://www.davincitandems.com/images/xt3.jpg

Mark Stonich has shortened cranks from a variety of sources: here's a little reading material:
http://mnhpva.org/meetings/July_03/Crank.html http://bikesmithdesign.com/Short_Cranks/Dotek.html

Jeff

 

[Bentbiker]

Perry, how about a set of crank shorteners from the Hostel shoppe? they would make the "Q" a little
wider, but all in all, a less complicated and hassle free modification

Perry wrote:

> Hi Earl, I do have IPS. (and I believe they're tapered) Why does that make a difference? Perry
>
> "Guess Who I Am" <[email protected]> wrote in message
> news:[email protected]...
>
>>Hello: if you donot have IPS or splined crank i know of a machine shop that will
>
> drill
>
>>and tap them out for you. if intrested please e-mail me back. Thank you Earl GRR,RANS V2 Ti
>>Rush,Ti Pursuit
>>
>>

 

[Tom Thompson]

"Jeff Wills" <[email protected]> wrote in message
news:[email protected]...
> "Perry" <[email protected]> wrote in message
news:<[email protected]>...
> > There is positively NO WAY I will ever give up IPS. Not until they pry
my
> > cold dead toes from my Frogs. With a big battleship hulking bike like
the
> > Double Vision, there are just too many needs for the IPS. Perry
>
> )
>
> If you're not going to give up IPS, then drilling and tapping the cranks is just about your only
> choice. It'll still require a good machinist to do the deed, but it's not terrible complex.
>
> They'll need to be shortened quite a bit, though, since enough material needs to be left on the
> outside of the pedal eye to keep them from cracking. You'll probably end up with 145mm or 150mm
> cranks, kind of like these cranks from DaVinci Designs:
> http://www.davincitandems.com/images/xt3.jpg
>
> Mark Stonich has shortened cranks from a variety of sources: here's a little reading material:
> http://mnhpva.org/meetings/July_03/Crank.html http://bikesmithdesign.com/Short_Cranks/Dotek.html
>

I'm using a set of Mark's 155s drilled and tapped for triople rings. The crank and matching rings
were about $150. He did a great job.

I've never even seen an IPS-equipped bike, so I can't tell you if these cranks could be modified to
work. I'm sure Mark knows, and could probably to the machining for you.

Tom Thompson

 

[Don]

Just trying to learn something here. Is the IPS integral to the crank? Meaning you buy it all
together and have limited choice on crank length. Don

 

[Mark Stonich]

"Tom Thompson" <[email protected]> wrote in message
news:<[email protected]>...
> "Jeff Wills" <[email protected]> wrote in message
> news:[email protected]...
> > "Perry" <[email protected]> wrote in message
> news:<[email protected]>...
> > > There is positively NO WAY I will ever give up IPS. Not until they pry
> my
> > > cold dead toes from my Frogs. With a big battleship hulking bike like
> the
> > > Double Vision, there are just too many needs for the IPS. Perry
>
> > )
> >
> > If you're not going to give up IPS, then drilling and tapping the cranks is just about your only
> > choice. It'll still require a good machinist to do the deed, but it's not terrible complex.
> >
> > They'll need to be shortened quite a bit, though, since enough material needs to be left on the
> > outside of the pedal eye to keep them from cracking. You'll probably end up with 145mm or 150mm
> > cranks, kind of like these cranks from DaVinci Designs:
> > http://www.davincitandems.com/images/xt3.jpg
> >
> > Mark Stonich has shortened cranks from a variety of sources: here's a little reading material:
> > http://mnhpva.org/meetings/July_03/Crank.html http://bikesmithdesign.com/Short_Cranks/Dotek.html
> >
>
> I'm using a set of Mark's 155s drilled and tapped for triople rings. The crank and matching rings
> were about $150. He did a great job.
>
> I've never even seen an IPS-equipped bike, so I can't tell you if these cranks could be modified
> to work. I'm sure Mark knows, and could probably to the machining for you.
>
> Tom Thompson

Some 175s can be retapped to 152s if there is enough material around the new hole. Usually there is
not. I wouldn't use IPS if it was free, had no extra parts to fail, and didn't add weight.
Especially if the alternative was an end to knee pain.

 

[Jeff Wills]

[email protected] (Don) wrote in message news:<[email protected]>...
> Just trying to learn something here. Is the IPS integral to the crank? Meaning you buy it all
> together and have limited choice on crank length. Don

Yes. Vision's Independent Pedaling System inserts a freewheel mechanism between the crankarms and
the chainrings on both the captain's and the stoker's cranksets. That way either rider can pedal or
coast at their pleasure.

Jeff

 

[Russ Price]

Jeff Wills <[email protected]> wrote:
> Yes. Vision's Independent Pedaling System inserts a freewheel mechanism between the crankarms and
> the chainrings on both the captain's and the stoker's cranksets. That way either rider can pedal
> or coast at their pleasure.

Shades of the Shimano FF (Front Freewheel) system of the '70s. However, the only FF bike I ever
rode, a 1977 Schwinn Caliente that I used to use, had permanently integrated chainrings and
Ashtabula-style crankarms and BB. It was basically a Varsity with a fancy drivetrain; it also had
the Positron rear mech, Shimano's first attempt at indexed shifting.

FF also had an oddball cluster with a one-way slip clutch on each sprocket, in case the chain
jammed. A flange on the cluster had a stamped warning that it was for use only with FF.

With FF+Positron, you could shift at any time, but starting off was awkward if you downshifted while
stopped. The Positron also used a solid shift cable, which tended to break from fatigue, either at
the shifter or at the derailleur. One of today's 7- or 8-speed gearhubs with a conventional crank
would be much better from a shift-at-any-time standpoint. I'm surprised, though, that Shimano never
thought of using the FF cranks for tandem IPS, whether or not the funky cluster was used.

I still have the old Schwinn, but damage/rust on a seat stay and worn-out teeth on the big ring have
made it unsafe to ride.
--
Russ [email protected] the wabbit to despam "No, see, it's not something
you 'experience' - it's something that you posess. You know, that fine 'recumbent butt' - a
distinguishing characterisitic of a recumbent cyclist." -Geoff Adams, on 'BROL

 

[Jeff Wills]

Russ Price <[email protected]> wrote in message
news:<pzkob.65809$Tr4.183512@attbi_s03>...
> Jeff Wills <[email protected]> wrote:
> > Yes. Vision's Independent Pedaling System inserts a freewheel mechanism between the crankarms
> > and the chainrings on both the captain's and the stoker's cranksets. That way either rider can
> > pedal or coast at their pleasure.
>
> Shades of the Shimano FF (Front Freewheel) system of the '70s. However, the only FF bike I ever
> rode, a 1977 Schwinn Caliente that I used to use, had permanently integrated chainrings and
> Ashtabula-style crankarms and BB. It was basically a Varsity with a fancy drivetrain; it also had
> the Positron rear mech, Shimano's first attempt at indexed shifting.
>

Not quite- the Calientes of that era had "Positron II". The original Positron (that was never used
on Schwinns, AFAIK) used a dual-cable system with indexing at the derailleur.

You're right about the IPS being similar to the Front Freewheel system- almost exactly the
same, in fact.

<snip>
> I still have the old Schwinn, but damage/rust on a seat stay and worn-out teeth on the big ring
> have made it unsafe to ride.

So go buy an old Varsity and swap out the drivetrain. It all interchanges. Old Schwinns never die-
they're tougher than cockroaches.

Jeff Wills (Schwinn mechanic 1979-1984)