Bike for big AND tall person

wrote in message
...
The new commuter wheels are Shimano XT hubs to Mavic rims, 36 hole
with double butted spokes assembled with blue Loctite. 2" slick city
tires with Kevlar are holding up well after 4000 miles. I believe the
Loctite was the key as both the new and rebuilt old wheels have now
remained true and sound.

I don't think Locktite is necessary, and (from recent experience) it is a PITA
when it comes time to replace a worn rim. Locktite makes wheel truing
difficult, without necessarily also making it unlikely. Sufficiently tightened
spokes won't unscrew, even on the left rear, which is the only potential
trouble spot.

I have had excellent luck with my Gary Fisher Tarpon. (non suspension)

Personally I feel that unless you get a "REAL" suspension, all you are going
to do on the "lightweight" suspension is bottom em out.

Stick with steel, non suspension....

(Chalo) wrote in message . com...
Zippy the Pinhead wrote:

I am 6'8" and 360lbs, and I would strongly advise you to avoid
ultra-tall frames made with small-diameter tubing (like the Redwood)
unless they are unusually heavy. My experience with such bikes is
that they are wiggly to the point of instability, and that they are
more prone to structural failure than frames made from oversized
tubing.

What diameters qualify as "oversized" depends on the material in
question: For instance, in a steel downtube, 1 1/4" (32mm) is
oversized, but for aluminum you're looking at 1 3/4" (44mm) or more.


That is a ridiculously over-simplified analysis. You neglect to take in
a key variable, and that is thickness of the tubing. Much of
the oversized tubing have very thin walls and can be less stable
under load than smaller diameter, thick-walled tubing. And if you
are going to make statements about failure rates, please provide the
data (not anectdotes, which you neglect to include also) to back up
the assertion.

Rather than go off on tangents which are meaningless without including
all the variables it would be much more fruitful for the person to talk
to actual owners of the tall Rivendell's. I know of a couple of BIG &
TALL folks riding the 68cm Rambouillet and Redwoods and they love the
bikes and do not think they feel unstable. I do not think these bike
have been around long enough for anyone to make any conclusion on
failure rate, but I suspect it will be low like other lugged steel frames.

- rick warner

(Rick Warner) wrote:

(Chalo) wrote:

I am 6'8" and 360lbs, and I would strongly advise you to avoid
ultra-tall frames made with small-diameter tubing (like the Redwood)
unless they are unusually heavy. My experience with such bikes is
that they are wiggly to the point of instability, and that they are
more prone to structural failure than frames made from oversized
tubing.

What diameters qualify as "oversized" depends on the material in
question: For instance, in a steel downtube, 1 1/4" (32mm) is
oversized, but for aluminum you're looking at 1 3/4" (44mm) or more.

That is a ridiculously over-simplified analysis. You neglect to take in
a key variable, and that is thickness of the tubing.

Hence my exception for *unusually heavy frames* of normal tubing
diameters. I have an old '70s Schwinn World Traveler, for instance,
that is adequately stiff because it is monstrously heavy (thick
walled).

There was no need, in context, to dazzle the OP with a complex answer
to a simple question. I understand the effect of tube stiffness being
almost proportional to wall thickness in bike tubing sizes. It is
also proportional to the third power of diameter, which has a much
greater effect on stiffness for that reason. There are other
generalizations that can be made due to conventional manufacturing
practice. Among those safe generalizations is that standard tube
diameters are unsuitable for a 300 pounder on a 68cm frame.

And if you
are going to make statements about failure rates, please provide the
data (not anectdotes, which you neglect to include also) to back up
the assertion.

I have bent some steel frames in the span of a single ride, more than
once-- no crashing necessary. I have bent too many 1" steel forks to
count; only a couple of 1.125" forks though, and none in 1.25". I
have observed firsthand that the difference between normal and
oversized tubing is often the difference between a bike I can keep,
and a bike I destroy quickly. I don't need "data" about other
people's bikes to know this.

Rather than go off on tangents which are meaningless without including
all the variables it would be much more fruitful for the person to talk
to actual owners of the tall Rivendell's. I know of a couple of BIG &
TALL folks riding the 68cm Rambouillet and Redwoods and they love the
bikes and do not think they feel unstable.

Just because some tall riders may like their 68cm Rivs does not mean
those bikes are stable-handling. It most certainly does not mean that
those bikes have similar handling to the same bikes in smaller sizes,
under smaller riders. I have an old 27" size lugged Nishiki touring
bike with Rivendell-like geometry and straight-gauge tubing much
heavier than anything Rivendell offers. I find that the front end can
lean to and fro without the rear end doing the same, and I find it
disconcerting. That bike may not be the equal of a Redwood in any
other respect, but it is stiffer than a Redwood by virtue of tubing
thickness alone.

My first adult bike was a lugged 68cm Schwinn World Sport ca. 1987.
Not only did it squirm around amusingly under my then 280 lbs, but it
was bent and ready for the trash heap in less than 3 months' riding.
And it was heavier and therefore stiffer than any Rivendell offering
in that size.

Traditional tubing diameters and gauges were developed to give
desirable handling characteristics in ordinary sized frames ridden by
ordinary size riders. Make the tubes longer and they become more
flexible. Increase the rider's weight and strength and it's no
mystery why such a bike might handle badly.

A 68cm frame with a 300 pound rider is going to be a lot floppier than
a 56cm frame with a 160lb rider, no matter what gauge tubing is used,
if it features the same diameters as the smaller frame. Even
*doubling* the wall thickness would compensate only for the increase
in rider weight and not for the increased tube lengths. You obviously
do not fall within the height and weight category under discussion, or
you would already have observed what I'm talking about.

I have corresponded with the folks at Rivendell about their tall
frames. A quote from Bhima Sheridan: "The Atlantis uses .9/.6/.9
double butted tubing for the top and down tube which is plenty strong,
but not the thickest tubing out there." They use this modest
thickness tubing in _all sizes_ of the Atlantis, which is just wrong
if the objective is to maintain some nominally comparable resistance
to twisting and flexing among different sizes.

I do not think these bike
have been around long enough for anyone to make any conclusion on
failure rate, but I suspect it will be low like other lugged steel frames.

They might be made of stronger steel than that in the lugged bikes I
have bent-- one would hope, anyway. All else equal, they will still
fail earlier than frames made with bigger diameters.

I suspect that the failure rate for traditional lugged steel frames in
68cm, when ridden by 300+lb riders, could not accurately be called
"low". Any kind of normal frame construction is going to have a
higher than normal failure rate in such circumstances. The folks at
Rivendell don't do any worse a job than most manufacturers at
constructing tall bikes for big riders, they just make taller bikes
than most. And they don't build them appropriately stiff or strong.

You didn't mention what size you are. If you are of average height
and weight, ask yourself this: Would you like a bike that flexed 3 or
4 times as much under you as your bike does now? Would you trust one
like that? Because that is what Rivendell offers to tall, heavy
riders like me and the OP.

Chalo Colina

"Frank Eparvier" wrote in message
...
Thanks to all who responded, especially you other "big guys" with
your personal experiences. I've investigated some of the custom
frame makers in the area (Zinn, for one), but am not certain my
first barely-serious foray into cycling is worth the amount of money
he wants, maybe sometime in the future ...

Look at it in another way: if you can make yourself spend more than you
think reasonable, you will fool your body into exercising to justify the
expense, and your heart and lifespan will benefit more than your wallet
suffers.

SteveC

"Chalo" wrote in message
om...
(Rick Warner) wrote:
I do not think these bike
have been around long enough for anyone to make any conclusion on
failure rate, but I suspect it will be low like other lugged steel frames.

They might be made of stronger steel than that in the lugged bikes I
have bent-- one would hope, anyway. All else equal, they will still
fail earlier than frames made with bigger diameters.

I suspect that the failure rate for traditional lugged steel frames in
68cm, when ridden by 300+lb riders, could not accurately be called
"low". Any kind of normal frame construction is going to have a
higher than normal failure rate in such circumstances. The folks at
Rivendell don't do any worse a job than most manufacturers at
constructing tall bikes for big riders, they just make taller bikes
than most. And they don't build them appropriately stiff or strong.

This was my impression also. I have ridden a number of 68 cm steel frames with
standard tubing diameter, and find them to flex significantly, even at my
(relatively) low weight (235). Torsional flex becomes an issue with large
frames, large diameter tubes make a big difference. My Cannondale (like
Chalo's) has a huge downtube for torsional stiffness. I have spoken with a few
other riders my height and approximate weight with conventional steel lugged
frames in large sizes, they all noticed significant frame flex. When I spoke
with (perhaps the best known East Coast) frame builder about a custom frame
for me, he admitted that, while he could build me a frame big enough, he
wasn't sure I'd be happy with it. Other large (lugged steel) frame makers have
resorted to unusual designs, like a double toptube or a diagonal tube to
stiffen the frame.

On the issue of lugged frames and strength, as well-known poster to this group
(Jobst Brandt), who's also a tall cyclist (and mechanical engineer and bicycle
expert), has pointed out that lugged frames have a design weakness in that the
boundary between the lug and the tube forms a natural stress riser. This claim
was accurate in my case, as I had a lugged frame fail with a headtube fracture
right along the downtube lug (the known point of maximum stress). Carefully
designed lugs can minimize this problem, but most people buy lugs for the
retro-look, not for functionality. Jobst points out fork crown lugs that have
been particularly badly designed in the past (and failed predictably).

Another dimensional issue for tall riders/frames is wheelbase and chainstay
length. Chainstays these days are fashionably short. There is no advantage to
short chainstays, and for stability, large frames should have proportionally
longer wheelbases. I was disappointed to see that even frame makers
specializing in tall frames, like Leonard Zinn, stick with minimal
chainstays/wheelbase. This is plain wrong. Touring frames are the only ones I
know of these days that extend wheelbase even a little beyond the minimum.
Heavier riders also need wider tires, and too many frames today won't take
anything over a 25 mm.

You don't make pants for a tall person just by lengthening the cuffs, nor do
you make tall bike frames by lengthening some of the tubes. 10-20 years ago,
large frames were in fashion, nobody had their saddles more than a few inches
above the toptube. I knew people under 6' tall who owned 68 cm frames. I think
the Riv frames are more of a retro thing than a tall person thing. If your
saddle and bars are right down on the frame, you're not going to put the same
kind of torsional stress on it. In other words, a very tall frame may be
stiff/strong enough for a less-than-very-tall person.

I think the best stock geometry a tall person can get now is a touring frame,
and fat-tubed aluminum is a better material for large frames ridden by large
riders.

"Chalo" wrote in message
om...
(Rick Warner) wrote:
I do not think these bike
have been around long enough for anyone to make any conclusion on
failure rate, but I suspect it will be low like other lugged steel frames.

They might be made of stronger steel than that in the lugged bikes I
have bent-- one would hope, anyway. All else equal, they will still
fail earlier than frames made with bigger diameters.

I suspect that the failure rate for traditional lugged steel frames in
68cm, when ridden by 300+lb riders, could not accurately be called
"low". Any kind of normal frame construction is going to have a
higher than normal failure rate in such circumstances. The folks at
Rivendell don't do any worse a job than most manufacturers at
constructing tall bikes for big riders, they just make taller bikes
than most. And they don't build them appropriately stiff or strong.

This was my impression also. I have ridden a number of 68 cm steel frames with
standard tubing diameter, and find them to flex significantly, even at my
(relatively) low weight (235). Torsional flex becomes an issue with large
frames, large diameter tubes make a big difference. My Cannondale (like
Chalo's) has a huge downtube for torsional stiffness. I have spoken with a few
other riders my height and approximate weight with conventional steel lugged
frames in large sizes, they all noticed significant frame flex. When I spoke
with (perhaps the best known East Coast) frame builder about a custom frame
for me, he admitted that, while he could build me a frame big enough, he
wasn't sure I'd be happy with it. Other large (lugged steel) frame makers have
resorted to unusual designs, like a double toptube or a diagonal tube to
stiffen the frame.

On the issue of lugged frames and strength, as well-known poster to this group
(Jobst Brandt), who's also a tall cyclist (and mechanical engineer and bicycle
expert), has pointed out that lugged frames have a design weakness in that the
boundary between the lug and the tube forms a natural stress riser. This claim
was accurate in my case, as I had a lugged frame fail with a headtube fracture
right along the downtube lug (the known point of maximum stress). Carefully
designed lugs can minimize this problem, but most people buy lugs for the
retro-look, not for functionality. Jobst points out fork crown lugs that have
been particularly badly designed in the past (and failed predictably).

Another dimensional issue for tall riders/frames is wheelbase and chainstay
length. Chainstays these days are fashionably short. There is no advantage to
short chainstays, and for stability, large frames should have proportionally
longer wheelbases. I was disappointed to see that even frame makers
specializing in tall frames, like Leonard Zinn, stick with minimal
chainstays/wheelbase. This is plain wrong. Touring frames are the only ones I
know of these days that extend wheelbase even a little beyond the minimum.
Heavier riders also need wider tires, and too many frames today won't take
anything over a 25 mm.

You don't make pants for a tall person just by lengthening the cuffs, nor do
you make tall bike frames by lengthening some of the tubes. 10-20 years ago,
large frames were in fashion, nobody had their saddles more than a few inches
above the toptube. I knew people under 6' tall who owned 68 cm frames. I think
the Riv frames are more of a retro thing than a tall person thing. If your
saddle and bars are right down on the frame, you're not going to put the same
kind of torsional stress on it. In other words, a very tall frame may be
stiff/strong enough for a less-than-very-tall person.

I think the best stock geometry a tall person can get now is a touring frame,
and fat-tubed aluminum is a better material for large frames ridden by large
riders.

Hi - Thought that I would weigh in on the Rivendell Redwood. I'm a tall
guy, but I guess that I don't qualify as big (about 230). I picked up a
65cm Redwood about a month ago and have put about 300 miles on it. So
far, I really like the way that it handles and it does not feel flexy at
all to me. I've taken it up to some pretty high speeds (so far 45 mph is
my max) and it felt really stable. Overall, I am very happy with the
ride and fit of this bike.

If you've got specific questions about it, I'd be happy to answer them.

Lorenzo



--
--------------------------
Posted via cyclingforums.com
http://www.cyclingforums.com

I'm 6' 7", 210 pounds, and own a 68 cm Rivendell Redwood.

I can confirm that the Redwood frame flexes a little bit, but I don't
experience this as a bad thing (if it stays within certain boundaries,
of course). It is slightly noticable when accelerating, while standing
on the pedals and swinging the frame sideways and back. The backside of
the bike is then bent in the opposite direction from the frontside of
the bike (the handlebars are pulled to the left, while the right pedal
is pushed down and vice-versa).

I noticed the flex because the rim would touch the brake pads
intermittently (the rim was about .5 mm from the pad). I adjusted the
distance between the brake pads and now I don't notice a thing.

The thick tubing, I assume (and hope), will make sure that the frame
doesn't lose it's original shape.

Of course, excessive flex is a bad thing. But that's not what I
experience (with my weight, that is).

There are also a lot of advantages to the flexibility of
steel---durability, for instance.

My 2 cents,

Nyarlaho



--
--------------------------
Posted via cyclingforums.com
http://www.cyclingforums.com

I'm 6' 7", 210 pounds, and own a 68 cm Rivendell Redwood.

I can confirm that the Redwood frame flexes a little bit, but I don't
experience this as a bad thing (if it stays within certain boundaries,
of course). It is slightly noticable when accelerating, while standing
on the pedals and swinging the frame sideways and back. The backside of
the bike is then bent in the opposite direction from the frontside of
the bike (the handlebars are pulled to the left, while the right pedal
is pushed down and vice-versa).

I noticed the flex because the rim would touch the brake pads
intermittently (the rim was about .5 mm from the pad). I adjusted the
distance between the brake pads and now I don't notice a thing.

The thick tubing, I assume (and hope), will make sure that the frame
doesn't lose it's original shape.

Of course, excessive flex is a bad thing. But that's not what I
experience (with my weight, that is).

There are also a lot of advantages to the flexibility of
steel---durability, for instance.

My 2 cents,

Nyarlaho



--
--------------------------
Posted via cyclingforums.com
http://www.cyclingforums.com