Australian Cycling Forums - Bicycles Network Australia

DaveQB wrote:I'm new to TT bikes so take this with a grain of salt.
1. Try to get in a "turtle neck" position so your is not up in the wind but rather only as high as your back this reducing your frontal size.
2. To me, it looks like your hands can come up higher, closer to your head to create a more "bullet" shape at the front; less of a parachute shape. This is how my bike fit ended up with 3D Bike Fit.
https://www.instagram.com/p/BJw-vOJDxKd/

Thanks for the tips.

These photos were taken on the approach to a downhill 90deg left so I was starting to think about sitting up to brake into the corner. I normally try to keep my head at an angle or position so that I feel the wind on the back of my neck or 'buffeting' the collar of my cycling jersey that I wear when I'm training.

The loaned Argon18 that I raced for a few months before getting the Shiv had the ski bars on it but when I bought this bike, it had the flat bars. To me, it feels a bit more comfortable and aero because I can get lower. That's just the seat of the pants feel though.

DaveQB wrote:2. To me, it looks like your hands can come up higher, closer to your head to create a more "bullet" shape at the front; less of a parachute shape.

Depends on the individual if the Praying Mantis is faster or slower. Can't throw generalisations around when talking about aerodynamics...

Did your bike fit include aero testing (either wind tunnel or field testing)?

mikesbytes wrote:

DaveQB wrote:I'm new to TT bikes so take this with a grain of salt.
1. Try to get in a "turtle neck" position so your is not up in the wind but rather only as high as your back this reducing your frontal size.
2. To me, it looks like your hands can come up higher, closer to your head to create a more "bullet" shape at the front; less of a parachute shape. This is how my bike fit ended up with 3D Bike Fit.
https://www.instagram.com/p/BJw-vOJDxKd/

How much did your bike fit cost?

Here's the prices for 3D Bike Fit:

http://3dbikefit.com.au/packages/

I did two bikes in one session.
I recommend him.

rossocorsa wrote:

DaveQB wrote:I'm new to TT bikes so take this with a grain of salt.
1. Try to get in a "turtle neck" position so your is not up in the wind but rather only as high as your back this reducing your frontal size.
2. To me, it looks like your hands can come up higher, closer to your head to create a more "bullet" shape at the front; less of a parachute shape. This is how my bike fit ended up with 3D Bike Fit.
https://www.instagram.com/p/BJw-vOJDxKd/

Thanks for the tips.

These photos were taken on the approach to a downhill 90deg left so I was starting to think about sitting up to brake into the corner. I normally try to keep my head at an angle or position so that I feel the wind on the back of my neck or 'buffeting' the collar of my cycling jersey that I wear when I'm training.

The loaned Argon18 that I raced for a few months before getting the Shiv had the ski bars on it but when I bought this bike, it had the flat bars. To me, it feels a bit more comfortable and aero because I can get lower. That's just the seat of the pants feel though.

Sure. I understand. Just trying to help. Hopefully I did.

dalai47 wrote: Did your bike fit include aero testing (either wind tunnel or field testing)?

No

DaveQB wrote:

mikesbytes wrote:

DaveQB wrote:I'm new to TT bikes so take this with a grain of salt.
1. Try to get in a "turtle neck" position so your is not up in the wind but rather only as high as your back this reducing your frontal size.
2. To me, it looks like your hands can come up higher, closer to your head to create a more "bullet" shape at the front; less of a parachute shape. This is how my bike fit ended up with 3D Bike Fit.
https://www.instagram.com/p/BJw-vOJDxKd/

How much did your bike fit cost?

Here's the prices for 3D Bike Fit:

http://3dbikefit.com.au/packages/

I did two bikes in one session.
I recommend him.

seems quite reasonable

DaveQB wrote:

dalai47 wrote: Did your bike fit include aero testing (either wind tunnel or field testing)?

No

Then although your position looks good in the photo, there is no way to know if it is the optimal position for you.

I found even ridiculously small changes in position had a profound effect in changing my CdA! If you have a accurate power meter field testing can be beneficial if you can't get into a tunnel. Don't discount formal testing such as with Alex Simmons or even getting into a wind tunnel though. Even though my position looked reasonable, within 1 1/2 hours of tunnel time I'd saved ~43 Watts; 10 Watts from a helmet change, the rest positional.

How did your times change after that?

mikesbytes wrote:

DaveQB wrote:

mikesbytes wrote: How much did your bike fit cost?

Here's the prices for 3D Bike Fit:

http://3dbikefit.com.au/packages/

I did two bikes in one session.
I recommend him.

seems quite reasonable

I think so. I think I was there for over 4 hours.

dalai47 wrote:

DaveQB wrote:

dalai47 wrote: Did your bike fit include aero testing (either wind tunnel or field testing)?

No

Then although your position looks good in the photo, there is no way to know if it is the optimal position for you.

I found even ridiculously small changes in position had a profound effect in changing my CdA! If you have a accurate power meter field testing can be beneficial if you can't get into a tunnel. Don't discount formal testing such as with Alex Simmons or even getting into a wind tunnel though. Even though my position looked reasonable, within 1 1/2 hours of tunnel time I'd saved ~43 Watts; 10 Watts from a helmet change, the rest positional.

That sounds like fun. I'll do that one day. Just starting out in TT. A powermeter is next on my list

linds wrote:How did your times change after that?

If you're talking to me, I have no answer. First TT bike and bike fit was done straight away. I didn't want to injury myself with a backyard hack of a fit done by myself.

Not mine. I spotted this Cervelo P5X on my ride today. Not something you see every day.

biker jk wrote:Not mine. I spotted this Cervelo P5X on my ride today. Not something you see every day.

I've not yet seen one myself. Only photos. In photos they look like something from outer space. Completely way out there.

That one looks to have a pretty upright fit.

I complained about the braking of my P5 on hydraulic rim brakes, but changing to different pads (which were thicker to start with) and then tweaking the adjustment of the brake levers made a huge difference - it feels incredibly powerful. You just need to lightly touch the brake levers and it really stops in a big hurry.

So I wonder if the disc brakes on the P5X are really necessary?

On the talk of position on the bike, I did find that a position that seemed to be fast was also a bit beyond what I could manage for a long time - mainly around the shoulders/neck. Though with more riding and less time sitting at a desk that isn't as much of a problem now (ie on road bike or TT machine).

g-boaf wrote:

biker jk wrote:Not mine. I spotted this Cervelo P5X on my ride today. Not something you see every day.

I've not yet seen one myself. Only photos. In photos they look like something from outer space. Completely way out there.

That one looks to have a pretty upright fit.

I complained about the braking of my P5 on hydraulic rim brakes, but changing to different pads (which were thicker to start with) and then tweaking the adjustment of the brake levers made a huge difference - it feels incredibly powerful. You just need to lightly touch the brake levers and it really stops in a big hurry.

So I wonder if the disc brakes on the P5X are really necessary?

On the talk of position on the bike, I did find that a position that seemed to be fast was also a bit beyond what I could manage for a long time - mainly around the shoulders/neck. Though with more riding and less time sitting at a desk that isn't as much of a problem now (ie on road bike or TT machine).

The owner said that disc brakes were in fact more aero since the top of the fork doesn't have the airflow disturbed by the rim brake. He said the P5X was faster on the flat but didn't feel as good as the P5 on the climbs. I think Cervelo claim the P5X is 30 seconds faster than the P5 over 40km and 2-3 mins faster on an Ironman cycle leg.

One of the other claims I heard was that the P5X was designed in such a way that it just wasn't possible to put a traditional brake system on it.

I've not yet had a look at one close up, so I wouldn't know. It's getting like the hypercar "arms race" if you want to call it that with this development.

I do find the traditional P5 okay going uphill, but maybe that's more me as a rider. Mine doesn't have the big triathlon front fork and brake covers, but it does have the Aduro handlebars - and of course the well known Magura RT8 TT brakes (common on the P5).

I'd like to see that data that shows that the disc brakes have better aero

biker jk wrote:

g-boaf wrote:

biker jk wrote:Not mine. I spotted this Cervelo P5X on my ride today. Not something you see every day.

I've not yet seen one myself. Only photos. In photos they look like something from outer space. Completely way out there.

That one looks to have a pretty upright fit.

I complained about the braking of my P5 on hydraulic rim brakes, but changing to different pads (which were thicker to start with) and then tweaking the adjustment of the brake levers made a huge difference - it feels incredibly powerful. You just need to lightly touch the brake levers and it really stops in a big hurry.

So I wonder if the disc brakes on the P5X are really necessary?

On the talk of position on the bike, I did find that a position that seemed to be fast was also a bit beyond what I could manage for a long time - mainly around the shoulders/neck. Though with more riding and less time sitting at a desk that isn't as much of a problem now (ie on road bike or TT machine).

The owner said that disc brakes were in fact more aero since the top of the fork doesn't have the airflow disturbed by the rim brake. He said the P5X was faster on the flat but didn't feel as good as the P5 on the climbs. I think Cervelo claim the P5X is 30 seconds faster than the P5 over 40km and 2-3 mins faster on an Ironman cycle leg.

Hmm, the top of the fork on the old P5-6 had covers over the front brake, flush fitting with the fork, so I doubt that causes problems. See here:

http://www.slowtwitch.com/Products/Tri_ ... _4526.html

Ignore the dodgy looking shifters put onto the Magura brake lever. Mine are much neater and intuitive.

linds wrote:How did your times change after that?

If asking me then yes they did change for the better.*

* Putting that into context - I used to already average 40km/hr+ on a converted steel road frame during the 20km ride leg of Sprint tris before I started focusing on road TT's.

When I did I bought a Cervelo P3 aluminium frameset which is still in use - is comparable in aero the a P2C so couldn't justify the cost of an upgrade on an already fast frame. This is the bike I was tested on in the Monash Uni wind tunnel.



Note the above is not the final position or helmet. I dropped another 2cm of spacers plus focused on turtling the head more.

My times did improve a fair bit since then. But there are a number of other things that could have increased my average speed and not just my aero testing. I bought a SRM for the TT bike, raced a lot of TT's (number of trips to race in Wangaratta and your Wodonga course in that period) and did a lot of TT specific training which did result in a number of A grade wins plus a a few State Masters medals...

What's turtling?

The head is tucked down more, like a turtle when it's walking.

Foo

mikesbytes wrote:What's turtling?

Trying to pull your head down beneath your shoulders and back towards your torso. Drops your head lower out of the wind (reduces your A - frontal area in the CdA equation) and minimises the gap between the helmet tail and your back. The higher your head is above your torso, the worse it is.*

*warning - generalization

Note via the lines on the wall behind how much lower my head is in the second shot.

Yeh, its an entire bump down. And you face is still pointing the same way, so visibility is not compromised.

It looks like you have relaxed between the shoulders allowing the neck to drop and presumably the scapulars have moved a little closer

DaveQB wrote:Nice nitestick!! Those pics look professional.

How's the Fabric saddle?

Sorry, it's been a while since I've been fishing around on the forum. Love it. Was devastated to scuff it in a recent crash but I sanded down the rough plastic and I'm still riding it. I'm not entirely certain it's great with my current skinsuits for long distances but I weathered our 80km TT championships on it for third plus an additional 60-70km for the day.