"FasterthanUR" <
[email protected]> wrote in message
news:FasterthanUR-
> Buck, BB is a very significant factor for climbing. It is not good to push the seat doing a hard
> long mountain streep grade climb. There is always a trade off. lot of touring bents have low BB
> height which reduces the chance of stressing the knees. Performance speed bents have high BBs to
> create a narrow front rider profile and incerase aero efficiency. With the knees at a high level
> the rider is positioning the knee joint at angle that extends forward more than a DF positiion. it
> is rare that a performance race bent allows for a low BB height. both of the bikes that Ed and i
> ride have low BB's which allow for efficient climbing with reduced knee strain.
I'm still trying to picture the differences in body positions. Let's talk in term of angles between
lines defined by three points, the BB, the rider's hips and the rider's shoulders. I'll call this
the rider angle. On grandma's 3-speed, the rider angle should be almost 180°. For someone in the
drops on an upright, the angle is nearly 90°, possibly lower. Rotating the body around the hips puts
us in the recumbent position. From most of the 'bents I have seen, the rider angle ranges from 120°
on recreational recumbents to nearly 180° on lowracers. By using the rider angle as the measure, I
see no way that raising the BB on a 'bent could move the rider angle anywhere near the setup on
diamond frames.
As I understand it, positions closer to 90° allow for greater force to be applied to the pedals as
well as a better aerodynamic position. The approach is just the opposite on recumbents - the rider
angle is pushed out to 180° to improve aerodynamics but isn't this significantly reducing the
maximum amount of force that can be applied to the pedals? You suggest that raising the BB is to
improve aerodynamics, but might the perceived increases in performance be due to lowering the rider
angle, thus improving the amount of force being applied to the pedals?
Measuring another angle might be useful. The angle between the BB, the hip and true horizontal,
which I suggest we call the BB elevation, may play a role here. I have suggested before that there
might be physiological reasons that factor into climbing on a 'bent because of rider position. On a
'bent with a higher BB on level ground, the BB elevation angle will be somewhere around 25°. When
the road goes up, the BB elevation goes up significantly. Perhaps there is a maximum BB elevation
beyond which our bodies just don't like to perform? Taken to the extreme, remember the old "bicycle"
exercise? Lie on the floor, elevate your feet and support your lower back with your hands, then
"pedal" the air like riding a bicycle. I always hated that one. The blood just rushes to your head.
Perhaps by lowering the BB on the bicycle, you are keeping the BB elevation angle below that
threshold when climbing, thus making climbing a more comfortable affair.
As I sit here and think about this, I keep coming back to the idea of rider position. Perhaps the
position of the rider relative to the earth is more significant than we realize. As a species, we
were meant to be upright when active, prone when resting. How does that factor into the performance
of 'bents, especially when climbing?
> But in the real
> > world, bicycle weight is a non-issue.
>
> I used to preach the same thing to a fellow racer till I rode in a severe hill race in WI in his
> area. Pushing a nearly 40 lb bike up steep long grades in a race was not good. Now that I've
> reduced t"he total bike weight by nearly half I know that in my current "real world of riding the
> weight reduction is a huge factor in climbing efficiency. that's just my opinion but there is
> vsome validity to that as some of the serious pro DF racers are riding sub 15 lb bikes instead of
> 20+ lb frames. the weight weinnies site even has a race bike listed that is 10 lbs.
I guess this goes back to the idea of all riders being equal. How many roadies do we see racing
professionally that weigh over 200lbs? When all of your competitors weigh 150 lbs, a five pound
difference in bike weight (3% of the total bike plus rider package) can be significant when riding
in the hills. For the rest of us, a ten pound difference (4.5% difference with a 180lb rider and
40lb bike) isn't going to mean much. I think I've sweated off nearly that much on some of my
longer rides!
> > Or is it more a function of the tendency to mash bigger gears because there is a support to push
> > against?
>
> I can't answer that one Buck. I only use gears I can spin. I know from my expoerience of racing
> some guys in the mountains in AZ on PACtour and then doing a severe hill race in WI that pushing
> big gears on a heavy bike is not effective and will ultimatley lead to an overuse injury. again
> this is partially due to the overall weight of the entire bike.
> >
I spin up hills also. I injured my knees while running and mashing big gears makes the pain come
back. Any other 'bent riders have a handle on how most 'bent riders climb?
> I can jump obstacles.
Really? How? I'll admit to limited experience, but I found that I could get the front wheel high
enough to clear the curb on a few 'bents although I was at a total loss on how to get the rear wheel
off the ground.
> Buck I just use the lowracer to train for racing. If I were to do a social ride with kids or
> family members I'd be using a MTB bike as there is more versatility for going over curbs and rail
> trails compared to my racing bent. There are some bents out there that have suspension and can
> ride up curbs and on gravel roads but they are very heavy weight bikes.
Ah.
> Is this just an overall average, or are you comparing heart rates when you
> > were climbing on the two different platforms? I would expect heartrate
to be
> > lower for a given speed on the flats, but what happens when the road
goes
> > up?
>
> Buck, when I train to race my HR is always higher than a longer distance or social ride. I'll push
> the hills aggressivley and will redline at times. It's similar to what I was doing when I raced
> DF's. Its just a different bike at this point in time.
For a given heart rate and angle of elevation, how do the speeds compare? When you are climbing a 6%
grade on your 'bent, do you have to put out a greater effort than on a DF?
> > More about the BB height! Maybe you can share your knowledge about the effects of BB height.
> > Have you ridden a machine that allows you to
adjust
> > the BB height as well as the length? Does such a bike exist?
>
> I do not know of any bents that allow for adjustable BB height. Makes it difficlut to find the
> right bent for your needs. One of the reasons I went through 7 bents prior. I was always looking
> for the most effficient, best handling, proper BB height bike for my need to race. I would not use
> my bike to commute as some of the roads where I live have no shoulder. I train durring the day
> when my schedlule permits and traffic is at low volume. However the guy that built the bike uses
> it to commute all over Europe as he owns no car.
>
> Unlike me, Ed rides his bike daily with no less than 60 mi per ride and most rides usually being
> 100 mi per day 7 days per week. He rides on all types of roads even in downtown Chicago traffic.
> Its all a matter of what the rider wants out of it all. I just prefer to ride for speed and not to
> use a bike for commuting. I've got my training routes and enjoy occassionally traveling to a race
> that will allow bents to participate.
Yeah, at this point we are running into the different uses issue. That's why I suggested in another
post that I would need two 'bents much like I have several DFs. If I want to go really fast, I pull
out the road bike. For most commuting and pleasure rides, I use a mountain bike. For off-road, I use
a full-suspension mountain bike. Once I had only one bike and two sets of wheels. One for commuting,
one for off-road. Now I am spoiled!
<snip>
> I might not be the best source for commuter style riding. If you go to this site:
>
http://www.bentrideronline.com/ you will learn a lot form other riders who are not into speed like
> I am. As I've said earlier, the stuff I'm interested in is a rather small niche and I'm enjoying
> it at this point in time but its not for everyone out there.
Thanks for the reference, I'll look into it a bit more.
-Buck
