I think that the main problem is crank length, provided you are not mashing. Even if you spin you
will run into the same problem if the crank is too long. You have to have to get the longest
possible crank for power, but short enought so that it won't cause repetitive strain injury.
The knee problem related to long cranks is to do the repetitve strain of over bending the knees. On
a DF/upright, it is my belief that you have less of a problem because you can slide your hips
opposite the rising knee side so that your rising knee does not get over bent (and equally, your
knee/leg on the down side does not get over stretched). You have wiggle room.
On a recumbent you don't have wiggle room, so the crank length had better be precise. Too short you
won't get pain, but you won't get optimum power. Too long and you will get knee problems.
The other problem associated with knee problem is the achilles heel tendonitis. To reduce knee pain
you might try to set your recumbent seat back a little. But if it is too far back you get repetitive
strain injury in the achilles heel.
Crank length must be correct!!!
I don't think tall people run into the problem when they purchase recumbents-- the crank may be too
short. But for shorter people, under 5'9" the cranks are generally too long on the factory built
bike. Getting short cranks can sometimes be an expensive proposition. A supply of short crank length
is something which mass manufacturers don't care about because it is a problem which DFers don't
face, only recumbent riders, shorter ones, who constitute a very small percentage of the population.
It is my belief that recumbent manufactures should not sell their bikes with cranks. There is a very
good chance that you have to change it.
"Bike" <
[email protected]> wrote in message
news:[email protected]...
> I have read "crank length" and knees in the same sentence may times. I have heard other
> suggestions too which have me at least thinking about
how
> to eliminate sore knees.
>
> What is meant by "pay very close attention to proper crank length."?
>
> If someone still has sore knees and is spinning and not pushing against
the
> seat back, they still have to "change" something. (Even "spinning" is not "really" defined, is it
> 90RPM?, 100?, should it be the same, when going, up-hill, down-hill, straight, into-wind???)
>
> Things I have heard which may help to minimize sore knees:
> o) Seat position, including angle (free) [adding a "wedge" under the seat now prevents me from
> sliding forward
]
> o) different clip-less pedals, maybe frogs ($130), maybe even with 1/4" to
> 1/2" extended length shafts (special order, needed with size 14+ shoes and others)
> o) maybe extending your current pedals out another 3/4" using shaft extenders ($35)
> o) maybe change the "crank length" ($$) but to what? (shorter?, longer?), If that does not work,
> try again with a shorter/longer length? (+$$)
> o) loose weight and exercise more (free??)
> o) try a different bike? ($$$$)
>
> It would seem to me that an "ergonomic" based range, similar to X-seam should be available to
> determine what a range should be for pedal shafts
and
> crank length.
>
> Seems like a lot of this is try and if it does not work, sell it if you
can
> and buy something else.
>
> Neil
>
> "Don" <
[email protected]> wrote in message
news:[email protected]...
> > Skott, pay very close attention to proper crank length. The rules can change depending on what
> > style of bike you are riding. I ride a road bike with 170mm cranks with no problem but the same
> > size is waaaayyyy to big on a recumbent with a neutral or high (relative to the seat) bottom
> > bracket.
> >
> >
[email protected] (skott) wrote in message
> news:<
[email protected]>...
> > > I have been an aggressive mountain biker for some years without knee problems despite the
> > > absence of my medial meniscus and posterior cruciate ligament. I have decided to become a
> > > roadie but am pretty convinced to do it with a recumbent. Probably a Volae Club when
> > > available. Are there knee problems unique to recumbents that may cause me problems??