Tubing Failure?

On 4 July, 00:53, "(PeteCresswell)" wrote:
Per thirty-six:

In light of comments so far, I'm going to revert to an old Titec
HellBent post and put enough more stem on the bike to maintain
the cockpit length... and see how it goes.

You can take your hands forward of the wheel hub, but I dont know how
far before it negatively affects control.


FWIW, I examined the welds on the third device - the one that
started it all and has been in service for five years or so - and
they are noticeably different from the two new ones: 25-30
percent less metal in the fillet or whatever it's called, and a
smoother fillet.

The fillet should probably be a little more than 1/8". It is up to
the welder at the time whether the weld is good. Working in dark
conditions helps so a dull red glow on both parts (outside the fillet)
is obtained for what is about twice the thickness of the metal can be
seen. Working in sunlight is guesswork and apparently (when cold)
sound joints can be made which are poor. Grinding the fillet smooth
is indicative of tidying up a poor weld. This is not acceptable on
high stressed structural components. The weld should essentialy be
left as it is, in little waves, without beading. Heat marking appears
as the weld cools and these also are pointers to a sound joint. In a
safety critical component all clues during welding and cooling should
be taken in. It is possible that these heat markings were ignored.

Use an extra long seatpost. *

You lost me on that one. *Seems like exposed seatpost length is
determined by one's leg length vs distance from pedal to saddle.

A longer leg extension, should your knees permit it, will bring you
forward (as well as taking the seat a little further back).


You've made me realise
though that maximum crank length is not only limited by femur length
but also shin length, each considered individually. *This may explain
why others of the same leg length can use longer cranks than me
without ill effect. *1/5 of leg length is a nice easy ratio to
remember though.

The bikes I built all have 180's. * My utility bike (an original
StumpJumper) came with 175's.

I can tell the diff, but I'm not sure one is better than the
other.

It's only overlength cranks which cause trouble, such as using 172s
with 30" legs (crotch to floor), I think that is hardly likely with
you. But, seeing as you have expressed a relatively short femur
length, perhaps this is also something to consider. As an example my
femur length is 18" and my tibial length is 17". I can just get away
with using 170mm cranks for up to two to three hours if pedal forces
are generally kept low, but for more time or high pedal pressure for
an hour then 165mm are much better and permit repeated riding on a
daily basis without deterioration due to stiffness or pain. I suspect
that the limitation for cranks should be basically made on the femur
length because the effective lower leg length (mine could be
considered anywhere between 20" and 22" measured at the heel or big
toe joint) is easily altered using more or less length in the foot.

You should find it easier to play around with limits of position using
shorter cranks anyway. It may be desirous for you to use short
cranks as a matter of course due to your disparity in skeletal
components. At least it wont be any trouble or great expense (dont
go for leg shortening) trying out median length cranks whilst you
experiment with position. Obviously it's going to feel peculiar and
although the familiar may have been working for you, there may be a
better way.

(PeteCresswell) wrote:
Per Peter Cole:
Why do you have so much setback? If you need more cockpit length why use
such a short stem? You wind up with a wheelie bike with slack angles
like a beach cruiser. Is that what you want?

It's not cockpit length.

Imagine you're spinning along.

Now imagine some rough ground ahead.

You up shift a couple of gears and pedal hard enough that your
butt just sort of floats above the saddle and your legs take the
brunt of the bumps.

Once the rough spot has passed, you downshift to start spinning
again. As your butt settles back down on the saddle, it will
naturally settle in a certain spot.

Without all that setback, that spot for me is right on the
rivets/rear edge of the saddle: half on the saddle, half off.

Sure, I can consciously pull forward and hit usable saddle....
but after about five minutes of pedaling, my sit bones are back
to hanging off the edge of the saddle.

Handlebar placement is not a factor. I have MTB bars with those
hooked bar ends on them - canted slightly downwards. This gives
me almost six horizontal inches of variance in the cockpit length
and a good two inches variance in bar height just by changing my
grip on the bars. All grips in all positions give the above
result.

Next time around, if I have a choice; I'm coming back exactly the
same size as Wallmart's "medium" men's clothing dummy.

I'm hardly average size myself. One of the conclusions I reached during
the time I tried to use various Brooks saddles was that they just
weren't long enough for me. After trying lots of saddles, I wound up
with a Titec Beserker on my MTB. It's a downhill saddle, so it's extra
long, which allows for sliding your weight forward and back to suit
conditions. A friend my age and almost my size is a semi-pro mountain
biker. We used to ride together a lot, but hadn't seen him in a few
years. I happened to meet up with him not long ago and it turned out we
had both discovered the same saddle and the same tires, neither being
very common around here.

I regard saddle setback as only affecting effective seat tube angle and
weight distribution. On a road bike I only want to set seat tube angle
since weight distribution isn't important and usually is fine. That
leaves stem length to set reach. It's the same on a MTB except that
(dynamic) weight shift is more important. Shifting the weight back is
necessary to lighten the front wheel to get over rocks and roots and to
prevent endos on steep descents. Getting weight forward is important on
steep climbs to prevent wheelies and losing steering. Hence the long
(flat) saddle.

With slack seat tube angles, your pedal stroke tends to push you back on
the saddle. The more the seat post inclines from vertical, the more the
reaction from your leg thrust does, too. Slack angles are fine if that's
what you want, but it sounds like that's a consequence of your butt
chasing the saddle, not your actual goal. Normally, I just decide where
my butt wants to be and center the saddle there. Sounds like you're
doing the same thing, but your butt seems to want a very unusual spot
(directly over the rear hub). I find that baffling. In years past, I
used to automatically set my saddles back as far as they'd go, assuming
that all my bikes were too small for my 6'10" size. As I started to pay
attention to riding posture, I started bringing them forward, now
they're all pretty centered. It's not a good way to adjust cockpit
length, only hip angle, which despite my size, tends to be typical.

Before I criticize or offer advice I think I'd need to go out and see
how I ride similar terrain. I guess it's automatic enough that I
wouldn't trust my memory. I do know that when I set up the last road
bike I built up from components I spent a lot of time (hours) with it
mounted in a trainer experimenting with different stems and bars and
tweaking every angle and setback. I was looking to get "balanced" on the
bike, both seated and standing, especially when pushing hard. I wound up
changing things quite a bit.

Yesterday, I did a 10 mile or so off road, including one half mile or so
long flat swampy stretch that was covered in tree roots, riding in a
style similar to your description. I know I was frequently "hovering" my
butt over the saddle (hardtail bike) while pedaling, simultaneously
doing little front wheel lifts over the bigger roots and dipping in and
out of gullies. I don't recall, then or ever, finding myself way back on
the saddle. My bike is a stock 22" MTB, definitely a bit on the small
side, with a long saddle pretty centered on the rails and a long reach
stem. I don't feel cramped in the cockpit, although I'd love more
wheelbase and not have to use a crazy long seatpost (I think it's a 450)
extended to the min insertion line.

Here's a picture (most people have trouble imagining what 6'10" looks like):
http://mysite.verizon.net/%7Epeter_c...s/pa030007.jpg

I notice you use flat pedals and you mentioned your size 15 feet. I have
size 16 feet and couldn't imagine off road riding with flat pedals
(actually I can imagine it, having done it). I can't easily control the
position of my foot on the pedal when bouncing around on rough terrain.
When I was a novice mountain biker, I always would unclip for tricky
sections, now I make sure I'm clipped in.

On 4 July, 14:55, Peter Cole wrote:
(PeteCresswell) wrote:
Per Peter Cole:
Why do you have so much setback? If you need more cockpit length why use
such a short stem? You wind up with a wheelie bike with slack angles
like a beach cruiser. Is that what you want?

It's not cockpit length.

Imagine you're spinning along.

Now imagine some rough ground ahead.

You up shift a couple of gears and pedal hard enough that your
butt just sort of floats above the saddle and your legs take the
brunt of the bumps.

Once the rough spot has passed, you downshift to start spinning
again. * As your butt settles back down on the saddle, it will
naturally settle in a certain spot. *

Without all that setback, that spot for me is right on the
rivets/rear edge of the saddle: half on the saddle, half off.

Sure, I can consciously pull forward and hit usable saddle....
but after about five minutes of pedaling, my sit bones are back
to hanging off the edge of the saddle.

Handlebar placement is not a factor. * I have MTB bars with those
hooked bar ends on them - canted slightly downwards. * This gives
me almost six horizontal inches of variance in the cockpit length
and a good two inches variance in bar height just by changing my
grip on the bars. *All grips in all positions give the above
result.

Next time around, if I have a choice; I'm coming back exactly the
same size as Wallmart's "medium" men's clothing dummy.

I'm hardly average size myself. One of the conclusions I reached during
the time I tried to use various Brooks saddles was that they just
weren't long enough for me. After trying lots of saddles, I wound up
with a Titec Beserker on my MTB. It's a downhill saddle, so it's extra
long, which allows for sliding your weight forward and back to suit
conditions. A friend my age and almost my size is a semi-pro mountain
biker. We used to ride together a lot, but hadn't seen him in a few
years. I happened to meet up with him not long ago and it turned out we
had both discovered the same saddle and the same tires, neither being
very common around here.

I regard saddle setback as only affecting effective seat tube angle and
weight distribution. On a road bike I only want to set seat tube angle
since weight distribution isn't important and usually is fine. That
leaves stem length to set reach. It's the same on a MTB except that
(dynamic) weight shift is more important. Shifting the weight back is
necessary to lighten the front wheel to get over rocks and roots and to
prevent endos on steep descents. Getting weight forward is important on
steep climbs to prevent wheelies and losing steering. Hence the long
(flat) saddle.

With slack seat tube angles, your pedal stroke tends to push you back on
the saddle. The more the seat post inclines from vertical, the more the
reaction from your leg thrust does, too. Slack angles are fine if that's
what you want, but it sounds like that's a consequence of your butt
chasing the saddle, not your actual goal. Normally, I just decide where
my butt wants to be and center the saddle there. Sounds like you're
doing the same thing, but your butt seems to want a very unusual spot
(directly over the rear hub). I find that baffling. In years past, I
used to automatically set my saddles back as far as they'd go, assuming
that all my bikes were too small for my 6'10" size. As I started to pay
attention to riding posture, I started bringing them forward, now
they're all pretty centered. It's not a good way to adjust cockpit
length, only hip angle, which despite my size, tends to be typical.

Before I criticize or offer advice I think I'd need to go out and see
how I ride similar terrain. I guess it's automatic enough that I
wouldn't trust my memory. I do know that when I set up the last road
bike I built up from components I spent a lot of time (hours) with it
mounted in a trainer experimenting with different stems and bars and
tweaking every angle and setback. I was looking to get "balanced" on the
bike, both seated and standing, especially when pushing hard. I wound up
changing things quite a bit.

Yesterday, I did a 10 mile or so off road, including one half mile or so
long flat swampy stretch that was covered in tree roots, riding in a
style similar to your description. I know I was frequently "hovering" my
butt over the saddle (hardtail bike) while pedaling, simultaneously
doing little front wheel lifts over the bigger roots and dipping in and
out of gullies. I don't recall, then or ever, finding myself way back on
the saddle. My bike is a stock 22" MTB, definitely a bit on the small
side, with a long saddle pretty centered on the rails and a long reach
stem. I don't feel cramped in the cockpit, although I'd love more
wheelbase and not have to use a crazy long seatpost (I think it's a 450)
extended to the min insertion line.

Here's a picture (most people have trouble imagining what 6'10" looks like):http://mysite.verizon.net/%7Epeter_c...s/pa030007.jpg

Looks like a nice sized BMX


I notice you use flat pedals and you mentioned your size 15 feet. I have
size 16 feet and couldn't imagine off road riding with flat pedals
(actually I can imagine it, having done it). I can't easily control the
position of my foot on the pedal when bouncing around on rough terrain.
When I was a novice mountain biker, I always would unclip for tricky
sections, now I make sure I'm clipped in.

Per thirty-six:
At least it wont be any trouble or great expense (dont
go for leg shortening)

Way back when I was in high school and it wasn't cool for women
to be tall yet; I read about this girl somewhere up North of
Penna that was 6'4" - and who went to Sweden to get her limbs
shortened.

I always wondered how her life turned out.
--
PeteCresswell

Per Peter Cole:
various Brooks saddles was that they just
weren't long enough for me. After trying lots of saddles, I wound up
with a Titec Beserker on my MTB. It's a downhill saddle, so it's extra
long, which allows for sliding your weight forward and back to suit
conditions. A friend my age and almost my size is a semi-pro mountain
biker. We used to ride together a lot, but hadn't seen him in a few
years. I happened to meet up with him not long ago and it turned out we
had both discovered the same saddle and the same tires, neither being
very common around here.

I find Brooks too short too - but they're the only ones that are
wide enough for my 5.25" C-C sit bones (2.77-3.25" seems tb the
expected norm based on the saddle dimensions I've measured). With
a leather sling saddle like Brooks, the entire width of the
saddle is usable, as opposed to plastic saddles where the outer
inch or so is solid plastic rail.

FWIW, I have an Azonic downhill saddle hanging on my garage wall.

Dunno how it's dimensions compare with the Berserker, but when I
hold it up against my Brooks mounted on that crime-against-nature
setback appliance I have, it puts the rider's butt in almost
exactly the same position - without using the appliance.

So, bottom line, it seems possible that somebody riding a
downhill saddle on a regular post could be achieving the same or
nearly the same saddle position I'm getting from my Brooks
saddle/setback appliance.
--
PeteCresswell

(PeteCresswell) wrote:
Per Peter Cole:
various Brooks saddles was that they just
weren't long enough for me. After trying lots of saddles, I wound up
with a Titec Beserker on my MTB. It's a downhill saddle, so it's extra
long, which allows for sliding your weight forward and back to suit
conditions. A friend my age and almost my size is a semi-pro mountain
biker. We used to ride together a lot, but hadn't seen him in a few
years. I happened to meet up with him not long ago and it turned out we
had both discovered the same saddle and the same tires, neither being
very common around here.

I find Brooks too short too - but they're the only ones that are
wide enough for my 5.25" C-C sit bones (2.77-3.25" seems tb the
expected norm based on the saddle dimensions I've measured). With
a leather sling saddle like Brooks, the entire width of the
saddle is usable, as opposed to plastic saddles where the outer
inch or so is solid plastic rail.

FWIW, I have an Azonic downhill saddle hanging on my garage wall.

Dunno how it's dimensions compare with the Berserker, but when I
hold it up against my Brooks mounted on that crime-against-nature
setback appliance I have, it puts the rider's butt in almost
exactly the same position - without using the appliance.

So, bottom line, it seems possible that somebody riding a
downhill saddle on a regular post could be achieving the same or
nearly the same saddle position I'm getting from my Brooks
saddle/setback appliance.

My suspicion is that you may be trying to solve a saddle problem rather
than a bike fit problem. I can't use Brooks myself, because they're too
short and I'm not comfortable on a sling saddle. Even if I could, I'd
find them problematic for MTB riding, and some road riding, too, because
I couldn't shift my weight fore & aft. If Brooks are the only saddles
that give you the width you need, then I guess you're stuck adapting the
bike to fit the saddle, but, based on your description of your riding
style, I suspect you're making a large sacrifice for it.