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Masters Racing (All Disciplines) Race on the track or road or on your mountainbike in the Masters Category? Want to talk tactics, strategy and training with your peers?

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Old 05-09-13, 01:10 PM   #251
gsteinb
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Old 05-09-13, 01:40 PM   #252
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Looking good, buddy. Good luck this weekend. Grab that jersey.
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Old 05-09-13, 01:47 PM   #253
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Next race in that series is June 8th. Two in July. Last one is August 15th.
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Old 05-09-13, 01:52 PM   #254
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Hi, I noticed the rotated brake levers when you posted the photo of you racing on the bike. Braking with your thumbs is an interesting concepts. Hard to imagine it. Not sure if I'll try it.

BTW, when we were comparing brake levers a few months ago you pointed out that your levers had a "feature" that wasn't on mine. a couple of days ago I was scouring the internet looking for write ups and photos of modified Shiv cockpits and I found this:

http://www.cpsc.gov/en/Recalls/2012/...-Crash-Hazard/

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Originally Posted by Racer Ex View Post
Again, a bit of a cell phone camera optic, the difference is less than a millemeter...but there's some manufacturing +/- and bolt alignment that creates the bit of asymmetry.



Winner winner chicken dinner!

Drag reduction comes in two forms; shape and volume. While the brake levers aren't as good a shape as the base bar, setting the levers up like this reduces the volume the wind "sees" considerably. The air separates around the lever and, depending on speed, either only partially hits the base bar or reattaches on the trailing edge.

And, as a nice surprise, braking in this position is actually more secure and stable than in the "conventional" position. Took me zero time to adapt...actually gets me to the brake levers quicker as well.

If I had more confidence in my soldering ability I could clean this up further. It's no Tetonrider custom stem set up but it's not bad.

Based on the HDC test session the old set up got me around "magic" CdA. This no doubt drops that a smidgen.
I'd recite the aerodynamic drag force equation if I had it memorized but you're right about shape (drag coefficient) and volume (primarily frontal area) being primary contributors to drag. At first glance, I like what you've done because it effectively reduces the frontal area. What puzzles me is whether or not the total system drag goes down because is there a primary affect on the base bars being in "dirtier" air that might raise the system drag coefficient. A little wind tunnel time would answer that conclusively. My guess is that the cool factor is greater than the "smidgen" wattage benefit.
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Old 05-09-13, 02:03 PM   #255
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I'm longer and lower than I was. To be determined if that's good. To the best of my measuring ability fore-aft, angle, and seat height are all the same as prior.
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Old 05-09-13, 02:33 PM   #256
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Racer Ex, the cockpit of the Shiv looks totally cool - nice work.

Cleave, I have to agree with you on the aero analysis of the lever turned up to reduce frontal area.
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Old 05-09-13, 02:57 PM   #257
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this guy showed up today


That's what I have - in 120mm.
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Old 05-09-13, 03:05 PM   #258
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AZT; regarding that 68cm monster bike. Its a beaut for sure. But did you find it stiff enough for out of the saddle hard launching, etc.? As a builder I am curious if it was what you needed in the stiffness/strength area. When I did big and tall special builds I usually put in a lateral tube to ensure it was stiff enough. I guess if nothing else, it makes a nice place to mount water bottles and DT shifters that wasn't a mile away from the top tube...[
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Old 05-09-13, 03:07 PM   #259
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That's what I have - in 120mm.
likewise, 120
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Old 05-09-13, 03:17 PM   #260
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AZT; regarding that 68cm monster bike. Its a beaut for sure. But did you find it stiff enough for out of the saddle hard launching, etc.? As a builder I am curious if it was what you needed in the stiffness/strength area. When I did big and tall special builds I usually put in a lateral tube to ensure it was stiff enough. I guess if nothing else, it makes a nice place to mount water bottles and DT shifters that wasn't a mile away from the top tube...[
Nope, it's definitely not stiff enough. On a team ride, one of my mates said all the flex was making him dizzy.
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Old 05-09-13, 10:23 PM   #261
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The original Shiv had a nose cone over the front caliper, which the brake was integrated into. It was raced for a season like that then somebody forgot to pay off the UCI and they said "we just noticed you have a nose cone". This was the solution. It's not a huge drag generator because the air flow mostly attaches to the head tube, but it is seen a bit.

The thumb actuation is actually easier than a conventional set up, and a bit more secure as well.
Ah, the UCI - that explains that.

I'll rotate the brake levers on the B2 and see if I like it - thanks!
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Old 05-09-13, 10:24 PM   #262
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Nope, it's definitely not stiff enough. On a team ride, one of my mates said all the flex was making him dizzy.
Can you feel it flex?
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Old 05-09-13, 11:03 PM   #263
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Hi, I noticed the rotated brake levers when you posted the photo of you racing on the bike. Braking with your thumbs is an interesting concepts. Hard to imagine it. Not sure if I'll try it.

BTW, when we were comparing brake levers a few months ago you pointed out that your levers had a "feature" that wasn't on mine. a couple of days ago I was scouring the internet looking for write ups and photos of modified Shiv cockpits and I found this:

http://www.cpsc.gov/en/Recalls/2012/...-Crash-Hazard/



I'd recite the aerodynamic drag force equation if I had it memorized but you're right about shape (drag coefficient) and volume (primarily frontal area) being primary contributors to drag. At first glance, I like what you've done because it effectively reduces the frontal area. What puzzles me is whether or not the total system drag goes down because is there a primary affect on the base bars being in "dirtier" air that might raise the system drag coefficient. A little wind tunnel time would answer that conclusively. My guess is that the cool factor is greater than the "smidgen" wattage benefit.
Thanks for the recall notice. I want to get these changed out.

The lever position has been tested, though with a different lever set.

The "dirty" air is created by the brake levers is created regardless of position. The advantage of this position is both a reduction in frontal area, and providing a surface that allows the air to smooth and reattach.

Think of it like this:

It's a 911 Porsche drafting a 66 Chevy Nova. The Nova has to be driven through the wind either way.
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Old 05-10-13, 11:53 AM   #264
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There is definitely a "cool factor" with those rotated brake levers. They remind a little of leading edge devices. Except cleaner.

Ex, there is the bike without rider in the free stream, and then you put the rider on the bike in the free stream. That's the true configuration of the bike. Hands, arms, head (even with aero helmet) are much, much "dirtier" than the bike is, and no matter how small (or invisible) the bike is to the free stream, the drag coefficient of the rider is high and is NOT invisible. The total drag of the bike is with rider, not without. My thinking is that hands placed on the end of the aero bar, in the "control" position, create enough drag to more than overcome the lessening gained by rotating the levers. Or, by the tiny frontal area presented by the bull horns and head tube. You've done the testing, what have you discovered?
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Old 05-10-13, 12:08 PM   #265
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There is definitely a "cool factor" with those rotated brake levers. They remind a little of leading edge devices. Except cleaner.

Ex, there is the bike without rider in the free stream, and then you put the rider on the bike in the free stream. That's the true configuration of the bike. Hands, arms, head (even with aero helmet) are much, much "dirtier" than the bike is, and no matter how small (or invisible) the bike is to the free stream, the drag coefficient of the rider is high and is NOT invisible. The total drag of the bike is with rider, not without. My thinking is that hands placed on the end of the aero bar, in the "control" position, create enough drag to more than overcome the lessening gained by rotating the levers. Or, by the tiny frontal area presented by the bull horns and head tube. You've done the testing, what have you discovered?
I'm not clear if by aerobar if you mean the "bullhorn" ends or the actually aerobar extensions.

If it's the former that's an unoptimized position that you are in for a very small amount of time and actively steering or braking. For some TT's I might be "out there" once during the entire event. For the rest of the time those levers and base bar sit out in the airstream and aren't affected by the rider.

If it's the latter I'm not clear on what the question is.

But I will say that even a brake lever creates a significant amount of drag (try sticking your finger out of a window at 30 MPH).
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Old 05-10-13, 12:10 PM   #266
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When Giant did the aero-testing for development of the Propel, they built a dummy that, unlike the "DZ" dummy (molded from Dave Zabriskie) Cervelo uses, actually pedals. Cervelo's approach is of course far better than no dummy at all. One of the huge advantages of the testing Hermes and Ex are doing at the velodrome is that drag is measured for them specifically, and actually riding their bikes. That beats the tunnel approach, IMO.

The upcoming CA state TT will be quite the showdown in 50+. In addition to California speedsters like Ex, my teammate Peter will be there to see how he measures up, after a TT focus and some wind tunnel optimization over the last few weeks. Peter had a great TT for VOS, and feels he has improved quite a bit since then. We know Ex has sped up since VOS, so lookout. I was planning to be there, but decided I needed to stay in town for the last couple of weeks of my current job.
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Old 05-10-13, 12:10 PM   #267
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I am not an aeronautical engineer, but I would think that the hands present a fairly static kind of drag no matter what they are gripping. Every little bit helps.
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Old 05-10-13, 12:17 PM   #268
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I meant the extensions (I get the terms wrong, sorry). Hands, when "blunted" into a grip or fist are much cleaner than a "flat plate" palm, but are still significantly dirtier than the whole handlebar/head tube arrangement as presented to a free stream. As airflow over the hands and forearms sheds, it impinges disturbed air on the bicycle structures downstream. I tend to think that the shed air would be significantly disturbed by the time it gets to the bullhorn/basebar and brake levers that the brake levers wouldn't even present a significant increase in drag. Still, I don't know, I've not seen a wind tunnel model - just asking the fella who's done wind tunnel testing.

Hey, try sticking your hand out of the window of a helicopter traveling at 120 knots - it will turn the aircraft!
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Old 05-10-13, 12:18 PM   #269
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AzT, are you coming to Long Beach for the Senior Games?
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Old 05-10-13, 12:25 PM   #270
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Hey, try sticking your hand out of the window of a helicopter traveling at 120 knots - it will turn the aircraft!
We used to screw with new pilots by sticking our legs out when we had the doors pinned back in the Hueys.

With this bar set up there's not going to be a lot of deflected air from the hand position hitting the lever or ends. Some, but not a bunch, especially when I do my stacked hands.

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Old 05-10-13, 12:26 PM   #271
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Old 05-10-13, 12:51 PM   #272
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Ex, I may have been one of those "new pilots"!

Hermes - yeah, that's it!
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Old 05-10-13, 12:56 PM   #273
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AzT, are you coming to Long Beach for the Senior Games?
Yes, unless work intervenes.
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Old 05-10-13, 12:57 PM   #274
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Yes, unless work intervenes.
Here's hoping you're there!
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Old 05-12-13, 05:07 AM   #275
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likewise, 120
oddly the 120 seemed to be longer than than my old 120. started to have back issues as the saddle to bars on the new bike was longer. presumably outside the doable range for me. went to a 110 yesterday. I really hate changing bikes in season. Probably wasn't a good idea to keep racing the old one though.
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