bitingduck

After elite nats one year we were racing at Encino and one of the roadies who also does track was talking about how his mass start races at nats went "I felt like I was always in the wrong place, and was exactly where everyone else wanted me to be". It's tactically very different for a lot of roadies - everything gets compressed into a lot shorter period of time and distance, so people who do a lot of track racing tend to get more tactical experience, which does translate to the road.


Scratch race is very much an endurance event, not a sprint event. Track sprinting is a totally different sport. The finishing sprint in a major road race is much more like a team pursuit (with not necessarily everybody on the same team) than it is like a track sprint event. One year at nats qualifiers we had one of the weirdest scratch races I've ever seen - we started a full field of 24 riders, and something got into everybody's heads (maybe they thought it was a win and out?) when they hit the front and they each seemed to take one ginormous pull at max speed and then 2 laps later be gasping for breath off the back. I think 8 people finished, and the average speed was faster than at nats. It was like a 24 rider TP.

As Carleton pointed out - Cav is a two-time world champion in the madison (with two different partners). He won one of them more endurance style (1 point, but had a lap over the field) with 2nd and 3rd taken by pro 6-day racer pairs and the second one with a well known endurance rider (Wiggins) as a partner, which they won on points from sprints and had a lap along with the other leading teams (which also included many 6-day pros). I wouldn't bet much against Cavendish in any kind of track endurance race against anybody.

Divebrian

Not sure what the technical name is for this part, but I need to order a new one and figured someone here would know what it is and where to get a replacement. It is on a Dura Ace rear track hub, basically, it's the inside track nut on the rear axle. It has serrations on it that are in contact with the inside of the drop out and they are worn down, resulting in a pulled wheel under heavy acceleration. I have attached a few pictures so you can see the nut. It looks like it's separate from the nut behind it and can be replaced like the outter track nuts.

carleton

It's called the "grip nut" and yes, they do wear down and cause slipping. This also leads to the bearing cones being tightened when the wheel is tightened leading to seizing, and thus constant adjustment with the cone wrenches.

This is normal wear and tear. One the same order get more track nuts as well. Make sure that you order the correct pitch nuts. Front/rear Dura Ace threading is different.

carleton

If you want the actual part numbers to order the parts yourself, I'd ask over in Bike Mechanics and ask for part numbers.

gl98115

Shimano Code Y23U06000. Try asking your LBS to order it.

https://wheelsmfg.com/tech/PDF/hub/hb-7600.pdf

Divebrian

Thank you. My local bike shop said they would order them if they had a part number, but they weren't familiar with track hubs and understood if I got them from a shop that specializes in track stuff and had them in stock.

carleton

Hmmm....I'd find another LBS.

Track hubs aren't that much different than any others. Especially the axles, nuts, and bearings, etc...

It's a Shimano loose ball bearing hub. If they can't work on that, I wouldn't trust them with bigger stuff.

700wheel

Is this your hub?
https://bike.shimano.com/media/techdo...9830672572.pdf
If so it shows rear hub part numbers.

carleton

Does anyone have any good data regarding the gains from using aero tubing vs round tubed frames?

Round tubes can come in steel, aluminum, or carbon. Here is Andy Lakatoh's round-tubed carbon Parlee that he used in 2011:

topflightpro

I've seen data on tube shape in wind tunnels. Specialized produces a lot since they have their wind tunnel and like to use the data to sell the bikes.

That said, everything I have read shows that aeroframes can reduce drag and the watts needed to propel the bike. However, most of the data is presented in the number of seconds saved over a 40k TT.

I haven't seen any data as to how that translates to a sprint, scratch, crit... Still, any energy savings is likely to be beneficial. In many cases, it is the accumulated savings from an aero helmet, wheels, frame... that make the difference.

jfiveeight

Here they did a test that's not scientific, but pretty decent. How aero is aero? - BikeRadar USA

The difference for the frames between the road helmet and the aero helmet are .0235 and .0224, so using their data the frame is worth about .023CdA

brawlo

Just as with most things I think there's more to the equation. I remember back 6/7 years ago because I was looking at them, I saw that Cervelo's non aero tubed R5 tested to be just as aero as the aero tubed S series bikes.

But the Specialized Win Tunnel test is the best comparison that I've seen that isolates the frame. 50s over a 40km TT is a lot. Also consider that those tests usually mean an average speed of 40kph. So at track speeds where aero matters (TT and off the front efforts that are usually high 50-60+kph) the difference can be higher as the faster you go the more that aero matters. No doubt the data is out there in the hands of the likes of BT, British Cycling, Look etc, but I doubt we'd get to see it

carleton

Yeah, that's the kind of stuff that I've been seeing. The road TT stuff.

But, those folks are in aerobars and grind away at 90RPM. In talking with Mr. Tiemeyer he explained to me that the legs make a lot of turbulence...which I think was the reason they got rid of the top tube in the GT Superbike.

I remember seeing one chart that listed the best bang for the buck aero equipment upgrades. Front wheel, helmet, skinsuit, shoe booties were high up on the gain/$ ratio and rear disc, frame, and ceramic bearings were low. I'll see if I can find it.


So, to compare

- Aerobars
- 40kph/25mph
- 80-100 RPM

with

- Drop Bars
- 65kph/40mph
- 130-145 RPM

is tough. Lots more turbulence being churned up with the legs.

That's an interesting read, but it's about aerobars and road TT stuff.

I do believe that there are aero gains with aero frames. But, I think we have to take anything with a grain of salt when it's the manufacturer that's publishing the data. It wouldn't be smart of them to publish something that says, "Our new expensive aero frame is marginally better than a budget round tube frame."

It's also possible to get the aerodynamics wrong. I have a budget 5-spoke and wonder if it's any faster than other options knowing that just because it's 5-spoke doesn't make it faster.

Remember Aerospokes? (this isn't the one I have)



They are inexpensive, easy to find, yet they are rare on the competitive track racing scene. I think these were proven (or at least believed) to be pretty slow.

I 100% agree. I think the wind tunnel data is what may have been what led to the narrow handlebar revolution. Maybe proving that aero gains at high speeds were totally worth the awkward standing starts.

Early Team GB Superbikes used custom wide (38-40cm?) handlebars. But then there are pics with Hoy using 34cm Nittos in comp. Then Alpina started making the 33cm Sprint bars around the same time that 35 and 37cm Scattos came out.

I wish I had access to a wind tunnel or some college students did a proper experiment but at 130RPM in narrow drop bars as opposed to 90RPM in aerobars. 2 track bikes (one aero one round), same rider, same wheels, same bars, same position, simulating a flying 200 or scratch race finish, 130rpm, 30mph and 40mph.

I'm curious to know if the gains are on the order of 10%, 1%, 0.1%, or 0.01%.

carleton

Here's one that's been bouncing around for years. Source: https://speedissafety.blogspot.com/2...-for-buck.html



Aero frame is the least effective of all. Ironically, it's one of the most expensive.

Same data:



Basically, it's because the air around the frame is so "dirty" from:
- The front wheel chopping it up.
- Bars and arms splitting it up.
- Your chest acting as a big scoop pushing air down into your legs.
- Legs whipping it up.

that a super slick frame has a really difficult job trying to clean it all up.

carleton

@brawlo, I found this from 2012:

Olympics track cycling: Will technology win the war for GB? - BBC Sport

So, you are right.

My google-fu is pretty good, but I can't seem to find any pics, much less videos, of sprinters in a wind tunnel with drop bars.

With the Flying 200 being faster and the margins for making the cut getting smaller than ever, I'd imagine that they are all in the wind tunnel cranking it up to 45mph/75kph!

EDIT:

another:

https://www.telegraph.co.uk/sport/oly...g-success.html

It's worth noting that Hoy or Pendleton didn't ride any events with aerobars in 2012. They only did F200M, Sprints, Team Sprint, and Keirin...all in drop bars. So, it's safe to say that all of that wind tunnel time was in drop bars.

brawlo

And Joe Public isn't going to see any of that research , probably ever

Dalai

Check through the Journal's topic I created a few years ago. There was a link to a huge Thesis by L Underwood (The University of Canterbury NZ) called Aerodynamics of Track Cycling. Been a while since I've read through it so not sure if it has what you seek, but would be a great place to start.

carleton

Thanks for the reminder.

I just skimmed through maybe 20 of them. A few mention frontal area but no mention of bike aerodynamics that I saw.

topflightpro

There is a wind tunnel in Charlotte, just a few hours up the road from you.

topflightpro

I know Carleton's take on this, and I've done some searches on this, but what is everyone else's thought on having power on your track bike?

I have some extra cash and a hook up to get a discount on an SRM. I have SRMs on both my road bikes and have been training with power for close to 10 years now. I'm just newer to the track.

I get the argument that cadence, speed, and time are the most important factors, but sometimes it's hard to get accurate time data when out training, and part of me is craving to see my power numbers. At the same time, I have been told by a couple people, Carleton among them, that having power on the track is a nice luxury, but if you're doing your intervals at home on the road bike with a PM, then I should be good.

Thoughts?

Dalai

I've tested in a wind tunnel back in 2008 and found it extremely beneficial.

Dalai

Like you I had an SRM on my road bike close to 10 years now too (wired Pro unit bought used still going strong).

Now I have a mix of wired and wireless SRM's on my TT bike, CX bike and wired track SRM's on both track bikes! If familiar with power training and metrics and will effectively review and use the data why not? Especially if you can get it for a good price!

carleton

Some reading while you are waiting for others to reply: https://www.bikeforums.net/track-cyc...computers.html

I can think of 3,000 reasons why not

Also, for me it wasn't just about, "Well, I have a power meter, may as well use it...". I found that if I sold that power meter, I could use that money for other training/race related things (aero wheels, travel, coaching, etc...).

@topflightpro, you are an experienced cyclists but a new racer on the track. There are several things that you can do that are almost guaranteed to make you faster, stronger, fitter, and a better track racer that are covered in this tread. Maybe consider the power meter a finishing touch as opposed to being the thing that makes you fast?

If you have:

- Annual track pass
- A complete kit of chainrings, cogs, tools
- Home training gear (trainer, rollers)
- Skinsuits
- Aero front wheel
- Aero helmet
- Coaching (This speeds up the learning curve.)
- Shoe booties
- Different crank lengths, bars, etc... to experiment with to see what's best for your style and body type.
- Professional bike fit (by someone who knows how to fit for track) to get you aero and powerful.
- Travel expenses to race at other tracks (experience will win you more races than power).

Then a power meter would be a finishing touch

jsk

I'm also new to the track but IMHO it's just as useful for track enduros as it is for road racers. I find it useful to measure training load, set interval targets, evaluate pacing, and analyze races and efforts after the fact. Plus, after years of training with power on the road, I just find it easier to quantify efforts in terms of watts and kilojoules. I also started using WKO+ 4 this year, and I think the new metrics/iLevels and optimized intervals are particularly well suited to the track.

Judging from what I've seen at my local track, plenty of others agree. So if you see value in it and the cost isn't prohibitive go for it.

Brian Ratliff

5kph out of 77kph is 6.5% faster on the track than the road. Power relates to velocity by the cube, so a 6% increase in speed is represented by a 21% increase in power. The difference between 1400W and 1700W is about 21%, so that seems about right. A good road sprinter, at the end of a sprint, might put out 1300-1400W. A good track sprinter, fresh, on a flying 200 run might put out 1700W. Again, seems about right. Call it a wash between the aero gear/track surface of a track sprinter and the leadout of a road racer.