All time personal best achieved tonight

Jim Gerwing

Jim Gerwing

Well-Known Member
I am proud to announce an all time personal best in my chosen standard: a one hour time trial.
Tonight I went 42km in 59:25.
I allow myself a flying start, straight out, a safe turn around with another flying start back in. Start line is the finish line.
Factors in my favor: Cruzbike Vendetta, self-made tail box, V3.0(pic to follow, it may be upside down), self-made rear wheel cover, weather: fairly calm but not absolutely so, road: quite straight (I did hit a light), terrain: surface-paved, 9/10 quality, low rolling hills with about 1/3 flat.
Great bike, John.
Thanks for the customer support, Jim/Maria.
I think I could still go a little faster. If I hit all conditions right on, 44, maybe 45km/hr?
My next big goal is 55km in one hour, pulling out all the aero stops, that is, fully faired.
Why 55? Next year that will be my age.
Jim
 
Jim Gerwing

Jim Gerwing

Well-Known Member
Loaded for bear, uh-air

image(45).jpg
 
K

KiwiGuy

Well-Known Member
SWEET!

Well done Jim. Impressive time.

I'm curious about the hand position you used for this TT. Did you spend most of the time in the 'drops' as per your photograph here, or did you hold a higher hand position on the 'hoods'??

I'm interested because John has mentioned that his experience is that higher is faster.

Kind regards...
 
Jim Gerwing

Jim Gerwing

Well-Known Member
In the drops

KG, I spend close to 100% of my time in the drops. I find that a pistol grip on the hoods leaves my thumbs in a position to scratch my outer thighs close to the knee. Optimally, I would like some kind of aero-bar set up as seen in John's skunk works. That sort of set up would not have been good to learn on but as I add time on the Vendetta I'm finding I can mix up my grips and even use hand signals.
Thanks for asking and the kind remarks,
Jim
 
Eric Winn

Eric Winn

Zen MBB Master
Jim, hands up on the hoods

Jim, hands up on the hoods seems faster to me too but I haven't captured actual performance data to validate yet. I had 3 rides in with my new Stages power meter before my accident and hoods vs drops was one of the things I was going to compare on my typical 20+ mile (32+ km) out and back ride.

I'm leaning toward getting a set of John's bullhorns because riding the hoods also felt more comfortable and I seemed to have better control but I was going to try and compare multiple rides before I made up my mind.

Since you have a basis to compare against, you might want to try again staying close to 100% on the hoods. I can shift the brifters from there too but it is a little tricky.

Interesting about your thumbs and knees. We look to be similar in size but I don't recall getting close to my knees. When I get the bike where I can check I'll see how close I get.

Here are how my hoods are aligned with my bars. When on the hoods, I'm wrapping my thumb around up high on the apex, almost cupping them.

alt="Brifter and hood alignment to handlebars"


-Eric
 
MrSteve

MrSteve

Zen MBB Master
Aero!

Here's an idea I stole from a record-breaking European custom
carbonfibre low rider....

You guys -people with working/normal memories-
may remember that it set a record indoors, in a velodrome, was unfaired and that
the rider was male.
The controversy about the record was due to the rider using fairings on his pedals!
The rules had nothing specifically to say about faired foot-soles....

Think about fairing the flat soles of your shoes, in other words.

I like your tail fairing!

Keep it up!

-Steve
 
marshall2389

marshall2389

Guru
your feet do move quite

your feet do move quite fast. Every time you pedal forward that foot is going even faster than the rest of the bike (excluding the tops of the tires) and your leading foot is the first thing that meets the oncoming air. I'm curious how he made a shoe/pedal fairing, though.
 
marshall2389

marshall2389

Guru
pretty cool story about

pretty cool story about recumbents and pedal fairings. read the following forum thread:

http://recumbents.com/forums/topic.asp?TOPIC_ID=4512&whichpage=4
 
Jim Gerwing

Jim Gerwing

Well-Known Member
Last year

Last year I went over 40km/hr for one hour, 15 times. My best effort was 41.6km/hr on a diamond framed bike with aero bars. In these efforts though, I was experiencing a lot of numbness in my crotch and left arm. Of course, this was concerning. When I switched to the Vendetta, I also got a new cycle computer (Bontrager, wireless) and I noticed that it measured my regular course as being shorter than on my previous computer set up by about 250m over 20 k. Crotch problem gone, still get a little numbness in my arm.
So there was (is) a learning curve to get the most out of the V, probably a slightly higher measure of distance (making last year's timings slightly higher, and this year's gains harder to achieve. And my favorite road was 'fixed' making the shoulders bumpy or, in places, too dangerous for me (and I am admittedly slack on 'dangerous' but I have my limits). I've got a new road that I can live with (And there's one under construction nearby that, when finished, is going to be promising) and a few more inexpensive aero add-ons to try.
That said I'm really happy with the 42.4km/hr clocking and I think I can beat it.
That's more info than you asked for but thanks for asking,
Jim
 
currystomper

currystomper

Well-Known Member
10 mile TTs


I'm interested in the detail as I plan to do some timetrials in the UK and compare a stand diamond road bike with a Silivio rev 2, They will be 10 mile TTs - on a good day I'm a 20mph (32.2km/h) kind of guy so I'm interested to see how much faster I can go on the Silivio. Note my diamond times are done without tribars.

Please keep posting your times as I'm really interested to see your progress.

CS
 
Jim Gerwing

Jim Gerwing

Well-Known Member
New PB

42km in 58:49 for an average speed of 42.8km/hr.
Calm winds, lots of traffic-especially 5th wheel and semis(they provide a significant albeit brief buffet and useable 'draft' when they're going my direction. I added a wheel well in anticipation of adding a trailing body fairing. I was not expecting any benefit but a 46 second improvement on my previous PB is significant. AND I had to stop twice: once on the outbound leg for a light, once on the inbound leg for a train. I don't shut off my computer so I have to suffer a timing penalty for the deceleration and the acceleration back up to speed. When I'm stopped, the clock stops. All this to say that it only encourages me because I know there's more speed to get out of this current set up which is being cobbled together, evolving one might say.
I'll see if I can get a pic up.
ps, my paper aero hat(a newer, improved version from the one first pictured)sustained rain and hail damage on a previous outing but I'm going to use it a couple of more times before a rebuild.
Jim
 
MrSteve

MrSteve

Zen MBB Master
Looking Better and Better!

You're thinking of adding wheel covers, right?

If not, you ought to....

I used to bake for a living and I still bake our bread.
We're having pizza tonight, for example, with scratch-made dough.

To make the starter, I use my wire whisk to whip together the water, the flour, the yeast and stuff.

A wire whisk is made of wire.
Sort of like the spokes of a bike wheel: wire spokes.
Right?

So, if you have a whisk handy, try whipping it around through the air and listen to all that
air you're whipping up!

Compare that to whipping a spatula through the air, edge-on.

After you have your wheel covers figured out, think about adding a little bikini
fairing, mounted out in front of your feet!

-Steve




 
hamishbarker

hamishbarker

Well-Known Member
He already covered the rear

He already covered the rear wheel with plastic film because he has a disc brake and can there fore stick the film to the rim walls.
 
Eric Winn

Eric Winn

Zen MBB Master
Turbulent air flow from

Turbulent air flow from pedaling being funneled by the seat bottom and back over the rear aero wheel disc returning laminar flow as it leaves the rear of the bike reducing drag?

It would be interesting to see a smoke wand in a wind tunnel applied to Jim's creation to actually see what it is doing.

Jim, have you covered the bottom span of the wheel stays to avoid creating an air brake? See photo below.
wink_smile.gif



image(48)B.jpg


-Eric
 
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