TT Bike

[Startrek]

Hi All ,
I'm looking at buying a TT bike and don't know a lot ,has anyone got any
tips on them .I do have one drama i run with campy 11(super record i bloody love it ) ,and if i ever want to run a disc wheel i won't be able .Do i forget about runnning a disc will it really help that much (and believe me i'm a not good itt's and need as much help as i can get) .See i have zipps 404's with a 11 cas on them which then i can use on both bikes .
Which ones should i look at ,and in a perfect world i would buy a Specialized S
buy i need to sell children and dog for that ,and i really do like the dog:D

[MatthewL]

Is that the same dog that ate the ipod? Sell it now, I say!!

[Simonsky]

Lee, are you saying that you won't be able to run 11spd campy with a disk? That doesn't sound right. Can't see why you shouldn't be able to.

[j_young_80]

What size frame are you after Lee?

I've got a 54cm TT Orbea that you can try out - even just to have a go at riding on a TT setup.

[Startrek]

Bugger just lost my post ,thanks Jamie bike is to big need a 49 (plus might get Jamie germs).The disc cant carry a 11 cass on it ,or was it was to wide for a 11 setup something like that .What about tt shifters do they do them in campy???.
Jamie do you use a disc??

[j_young_80]

I don't use a disc and never have and i'd probably be arguing that your 404's would do fine for the first few races - you could always get an 808 for the rear.

I'm of the belief that there is a minimum number for the speed/power you need to be able to push for a disc to be worthwhile? Glenn D? Simon N or C?

[Startrek]

I have found out that you can't buy a 11 speed campy TT shifter ,campy don't make them yet ,did i test ride on a TT full carbon plus full carbon TT shifter bars and found the road vibration going through all that carbon tough.
So Jamie do you think as i'm not the strongest rider my power output is not enough for a disc and i would be wasting money ,i would like a 808 but they want to much for one .

[j_young_80]

I believe that is the case yes - however it's not an insult as I don't think that I can generate enough power to justify a disc wheel either....waiting for my comment to get flamed down any minute though! I vaguely remember listening to a podcast that insinuated this - i'll try to rustle it up to back up my unfounded claims.

[j_young_80]

OK so here's a quick google result that sort of backs up what I had heard more comprehensivley put in another podcast. However, this lists 20mph as the minimum where it's not worth using one which is 20 mile/hour (mph) = 32.186 88 kilometer/hour.

Your ITT time for Masters was 34ish I think? so I guess Roddy has to buy you a disc on that logic, especially seeing as it was probably a hillier ITT than most. I had the number 40k's an hour as being the bench mark in my head for some reason but without tracking down solid evidence I will yield.

http://www.bikesplit.com/bsa11.htm

Wheels have more impact on speed than any other component of your bike. Think of a fast rotating wheel as virtually solid, similar to the propeller of a airplane spinning at high speed. When a spoked wheel isn't moving plenty of air can pass through, but the faster it spins, the less air can pass through. In fact spokes create air turbulence and lots of drag. This is why fewer spokes and the shape of spokes makes a wheel faster. A disc creates much less turbulence, but has it's own source of drag, especially in crosswinds.
The mass of a spinning wheel also has to be accelerated many times during a race and this involves peak power output each time. This is why saving weight for wheels has more positive effect on speed than saving weigh from your frame. The further the weight is from a wheel's hub, the more effect it has on acceleration. The weight of the rim has more impact on acceleration than the weight of the hub.

For wheels to train on I choose by durability. For wheels to race on I spare no expense in getting the most aero as first priority, with light weight as second priority. I ride clinchers for training, and tubulars for race day. Clinchers are more familiar with a separate tube inside and a tire that fits to the rim with a bead that is smaller than the outermost rim diameter. Tubulars have a tube 'sewn-up' inside and must be carefully glued to a rim.

I prefer tubulars on race day for their ability to conform to road surfaces. They have thinner and taller sidewalls so are more able to absorb road shock than clinchers. This is helpful on rough roads, for example on a rough corner a tubular will be better able to keep the rubber in contact with the road surface.

For race wheels the size and speed of the athlete should impact wheel choice.

The taller the rim, the more affected it is by crosswinds. Light riders will have a proportionally tougher time controlling a disc wheel in a crosswind than a heavier rider. Even a deep rim wheel with spokes can be tough to control at times for medium to small riders. The 650c size is significantly easier to handle.

The advantages of aero wheels are proportional to speed. If your average race pace will be 20mph or less, I don't recommend a disc. A disc wheel is typically heavier and will drain energy more than help in the wind. A heavier rider who can develop lots of power will gain more advantage from a disc. The best all-round race wheels for most riders will be a light, deep composite rim wheel with few spokes.

[Chris]

I think you are right. From what I understand a disc may give us mortals a little extra but the marginal benefit is petty low compared to other things. I would also wonder how much we would use one in Canberra where there is a high chance of a cross wind.

I know Cevelo argues that slower riders get a bigger benefit because they are on the course longer, but that ignores the fact that drag is a power law (as speed increase drag increase by a power of 3.) Therefore the longer you are on the course (the slower the speed) the less dominant drag becomes and the less important lowing drag. Or the other way of looking at it, as you go faster drag increases disproportionately to the decrease in time you are on the course and therefore the greater the benefit you get from decreasing your drag.

[Chris]

Interesting Jamie, I had heard 40 km some where too. I know that aero is more important that weight in a TT by a long way. I remember hearing some numbers that put a 1kg of weight saving at only a few seconds over a hilly course. In fact you really had to be hill climbing to care about it.

This is of course different to a road race where you are hopefully hiding behind Jens as he drags you up the hill behind his mighty wind shadow.

[Startrek]

Thanks Jamie and Chris will now take that into account .

[j_young_80]

Lee - take what we say with a grain of salt! Did you see the link that I posted on time savings versus cost? Since the list is dealing with ITTs (with a swim and run thrown in) it's a pretty good guide on the most efficient bits to save time.

Here tis again http://www.tri-talk.com/Top20.asp

Under the category Most Time Saved a Tri Bike is listed at 4th with Aero Wheels 6th.

I heard a good method of "earning" your upgrades recently from a local triathlete - basically set yourself a benchmark for acquiring certain products - when you reach it, buy it. So if your current ITT avg speed is 34, set yourself a goal of 37 - if you make it, Disc Wheel is a go.

All that being said - didn't you just take out Gold at the Masters ITT? Give the fellow competitors a chance woman!

[Startrek]

Thanks Jamie ,i like the idea of earning it ,just finding the time to earn it is the problem.

[bosworth*]

I remember hearing: "For a TT, Always use the deepest dish wheel you have available, unless it is a very steep hill climb(no descent), or gale-force crosswinds"


I have no idea how accurate this is.

[Ross]

Jamie, can I take you up on your offer of a ride of your Obea TT bike? Maybe work something out for Saturday arvo if that's convenient for you? Can I keep it for a few days?

[j_young_80]

Shouldn't be a prob - it's still got my gold coast worlds numbers all over it and race wheels on but i'll flip them over this week.

[Startrek]

Jamie do you use full carbon shifters?

[j_young_80]

this is what's on there at the mo'

http://www.jensonusa.com/store/product/HB409D00-Profile+Design+Carbon+X+Tt+Bar.aspx

[Startrek]

I'm looking at puting on 3 T Brezza want do you think .

[j_young_80]

That;s looking pretty bling!

http://www.thenew3t.com/details.aspx?i=Aerobars&t=&p=brezza&d=TEAM

Hey BTW - do you know a guy called Duncan? turns out he's the boyfriend of my neighbour - and I think he might work at Ride Shop? he knew you and Vanessa and I tried to get him along to the friday squad ride.

[Startrek]

How old is he ? 20 or 40 i know two that belong to the Ride shop.

[j_young_80]

he's not 20 so lock in 40 thanks Eddie.