Oversize crankset/chainwheels

Suppose you want high performance from a 20" rear wheel. Logically you need at least 63 teeth
chainring. Maybe more with a fairing. Suppose you are into sprinting and want to beat the national
record or something

How can you go about getting one? Is best way to go to webstore and separately order custom and
standarad parts and put together a crankset yourself? Or can I just take a standard Shimano roadset
and change the largest chainring? At least on Shimano parts you have asymmetrically shaped teeth to
make shifting work better. Would it work smooth even if you have right form factor etc? How about
large jumps, like 39 teeth ring to 65 teeth ring. Can it work at all, would you need a MTB front
derailleur? I think Challenge Taifun has something like this, and maybe RANS.

--
Risto Varanka | http://www.helsinki.fi/~rvaranka/ varis at no spam please iki fi

 

<[email protected]> wrote in message
news:[email protected]...
> Suppose you want high performance from a 20" rear wheel. Logically you need at least 63 teeth
> chainring. Maybe more with a fairing. Suppose you are into sprinting and want to beat the national
> record or something

An intermediate step-up drive could solve the problem rather elegantly :
http://www.dalliegerad.com/shark.htm

I'd go with that.

Regards, Torben

 

Alligt in Eindhoven advertise big rings - the Challenge Taifun I was prodding at the races yesterday
had an Alligt-inscribed 65.

http://www.alligt.nl/ - Tandwielen.

For much filthy lucre, Highpath in Wales will machine any size you want.

http://www.argonet.co.uk/highpath/cycle_/eggs.htm

Dave Larrington - http://legslarry.crosswinds.net/
===========================================================
Editor - British Human Power Club Newsletter
http://www.bhpc.org.uk/
===========================================================

 

For a bit more flexibility: http://pictures.care2.com/view/2/733339897

rorschandt

 

U know everytime U time you park this, you'll have people asking more about the massive mid-drive
than any other part of the trike. Apart from the added weight a Chromed Cowl over it might be cool
for that Retro-Hog look especially if you do the frame in a purple Metal Flake (Hamster optional).
----------------------------------
"rorschandt" <[email protected]> wrote in message
news:[email protected]...
> For a bit more flexibility: http://pictures.care2.com/view/2/733339897
>
> rorschandt

 

rorschandt <[email protected]> wrote:
: For a bit more flexibility: http://pictures.care2.com/view/2/733339897

With such close distance, I'd think there would be chainline problems? Could sacrifice some
performance and durability

Would work better if the other cassette was rotated 180 degrees lateral But the derailleur would
have to work in reverse. Hello Shimano, are you listening? ;p

--
Risto Varanka | http://www.helsinki.fi/~rvaranka/ varis at no spam please iki fi

 

[email protected] wrote in news:[email protected]:

> rorschandt <[email protected]> wrote:
>: For a bit more flexibility: http://pictures.care2.com/view/2/733339897
>
> With such close distance, I'd think there would be chainline problems? Could sacrifice some
> performance and durability
>
> Would work better if the other cassette was rotated 180 degrees lateral But the derailleur
> would have to work in reverse. Hello Shimano, are you listening? ;p
>

The distance between cassettes is approximately that of an ordinary DF bike, so chain angles are no
worse than for what it was designed. I'm sure there is some more friction because of TWO separate
chain systems. Primarily, this was an engineering challenge for me, and I've managed to do it (~:
Also, I placed the mid-drive shaft so that it doubles as the rear suspension pivot. This de-couples
any pedalling action and suspension movement. It does nothing to neutralize the movement of
mass(legs) from giving suspension movement, but that has been no problem so far.

rorschandt

 

rorschandt <[email protected]> wrote:
: The distance between cassettes is approximately that of an ordinary DF bike, so chain angles are
: no worse than for what it was designed. I'm sure

Would think rear cassettes are wider than front ringsets :-/ Also the most useful gears come from
the most extreme chainlines.

--
Risto Varanka | http://www.helsinki.fi/~rvaranka/ varis at no spam please iki fi

 

[email protected] wrote in news:[email protected]:

> rorschandt <[email protected]> wrote:
>: The distance between cassettes is approximately that of an ordinary DF bike, so chain angles are
>: no worse than for what it was designed. I'm sure
>
> Would think rear cassettes are wider than front ringsets :-/ Also the most useful gears come from
> the most extreme chainlines.
>

I think you may misunderstand how it works, as in the pics there are no chains.The front cassette is
offset from the rear cassette,has a chainring on the back of it, which is connected by chain to the
rear cassette. The front cassette is driven by a chain coming from the front of the trike. Each
individual cassette and derailleur operates exactly as it would on a bike with only one cassette.
Individual chainlines are as they would be on a bike with only one chainring. Check the website for
new pictures. http://pictures.care2.com/view/1/844656287

rorschandt

 

> I think you may misunderstand how it works, as in the pics there are no chains.The front cassette
> is offset from the rear cassette,has a chainring on the back of it, which is connected by chain to
> the rear cassette. The front cassette is driven by a chain coming from the front of the trike.
> Each individual cassette and derailleur operates exactly as it would on a bike with only one
> cassette. Individual chainlines are as they would be on a bike with only one chainring. Check the
> website for new pictures. http://pictures.care2.com/view/1/844656287
>
> rorschandt

This is very ingenious...I was having a bash at working out the gear range. I came up with (assuming
2 x 11-32 cassettes and 2 x 22 drive rings, one on the boom and one on the back of the mid drive
cassette) a range of 6" - 150". Is this correct? If it is, this is an excellnt way to solve the
small drive wheel problem. The low gear will be very useful on a trike. How is the chainring
attached to the back of the midrive cassette? Are you using two 9sp bar end shifters, I would be
interested to know as I think I may be able to add a bolt on midrive myself...TIA David

 

Subject: Re: Oversize crankset/chainwheels Newsgroups:
newscache3.freenet.de:alt.rec.bicycles.recumbent To: David <[email protected]>

On 10 Apr 2003, you wrote in alt.rec.bicycles.recumbent:

>> I think you may misunderstand how it works, as in the pics there are no chains.The front cassette
>> is offset from the rear cassette,has a chainring on the back of it, which is connected by chain
>> to the rear cassette. The front cassette is driven by a chain coming from the front of the trike.
>> Each individual cassette and derailleur operates exactly as it would on a bike with only one
>> cassette. Individual chainlines are as they would be on a bike with only one chainring. Check the
>> website for new pictures. http://pictures.care2.com/view/1/844656287
>>
>> rorschandt
>
> This is very ingenious...I was having a bash at working out the gear range. I came up with
> (assuming 2 x 11-32 cassettes and 2 x 22 drive rings, one on the boom and one on the back of the
> mid drive cassette) a range of 6" - 150". Is this correct? If it is, this is an excellnt way to
> solve the small drive wheel problem. The low gear will be very useful on a trike. How is the
> chainring attached to the back of the midrive cassette? Are you using two 9sp bar end shifters, I
> would be interested to know as I think I may be able to add a bolt on midrive myself...TIA David

Hello, Yes, both units are 11-32.Try http://www.wisil.recumbents.com/wisil/gearinches.asp I brazed a
steel plate to the rear of a cassette body, and machined some inserts for the cassette body to
accept some cartridge bearings. As I recall, the gear inch range is 14 to 123 or something like
that. I'm using a 22th ring at the back and 34th at the crank. I could also use a front derailleur,
total 3 shifters, a potential of 243 combinations!...The shifters used are a regular set of Shimano
9spd bar-ends. The "left side shifter" will move a rear derailleur thru the complete range, it
merely is not indexed. It is a bit confusing to shift at first because both shifters run the
derailleurs identically. "Now I just shifted that one into the second smallest gear...wait, that was
the OTHER derailleur..."