[emartin]

Hi everyone, I'm about to order my first dedicated TT bike. I wasted my sunday evening searching about bike fitting and TT position...without real answers. So here's the deal: I'm 5'7" with a 80 cm inseem. I actually own a 53cm ZX3 PedalForce(535mm top tube) with a 11cm stem and it fit me perfectly. I will probably buy another PedalForce frame, here's a link to the frame the geometrie: http://pedalforce.com/online/product_info.php?products_id=11498

So what you guys think, am I better with a 515 or a 525mm? I'm leaning toward the 515 for some reason but need some input on this one.

Thanks, Emmanuel

 

[C-40]

thoughts...

There's a huge difference in the TT length. The smallest size must have an incredibly short front-center. The head tubes are all the same tiny 90mm?

The few times I've mounted aero bars to road bikes, I've felt like I needed a shorter stem to get the arm pads back far enough. The smallest size would certainly produce a short reach. The larger size is more like a normal road bike TT length, but the steep STA makes it longer. Your size selection might depend on whether you plan on using a lot more forward position. If you do, go with larger size.

 

[stevesbike]

just looking at the geo chart, one thing to consider is that the top tube measurements are based on a 75.5 seat angle. That's pretty relaxed for a TT/tri bike. Chances are you'd have a more forward seat position, which effectively shortens the top tube measurement so the 515 size (496) is going to be even smaller. The 525 might end up being a better fit. I like pedalforce (one of my bikes is an RS2) but I'd have to say that $1199 is pretty steep to me for this frame (you could get the same from direct from Asia for half that price).

 

[emartin]

I like pedalforce (one of my bikes is an RS2) but I'd have to say that $1199 is pretty steep to me for this frame (you could get the same from direct from Asia for half that price).

You are right about the price...I also saw the identical fram on ebay. PF offered me a great discount but still more expensive. PF also offer a less expensive TT frame, the Aeroblade which look identical to the planet X Stealth pro carbon. According to Planet X, a 48cm would fit me, any tought on that frame?

Thanks

 

[zender]

Did you try and run through Competitive cyclist's TT/Tri fit calculator?
http://www.competitivecyclist.com/za/CCY?PAGE=FIT_CALCULATOR_INTRO&INTRO_LINK=NOREDIR&SITE.CODE=TRI

If you have time, it might be worth going through their road bike fit calculator first to see if the numbers it comes up with are on par with what your current road bike is.

I'd be curious what you come up with, because my measurements for road bike fit come up spot-on to what I ride. But, for TT/Tri it says 54.5-56.5 top tube with a 8-10cm stem. I find a 54 cm top tube too long with a 76 degree seat-tube and have my saddle pushed all the way forward to achieve a 90 degree bend at the elbow.

 

[draganM]

How trustworthy is the competitive cyclist TT fit calculator? I'm getting ready to order a TT frame and I would rather not spend a lot of time and money shipping different frame sizes back and forth. Even that might not yield success as you really need to build it up to check for and once you do that you can't send it back as "new".
when I did the Road one it came up with very different results from what I ride. The frame I ride now 60cm I've been on for close to 2 decades and it's very comfortable for me. Effective top-tube on my road bike is 58.5cm+11cm stem = 69.5 . they recommend
The Competitive Fit (cm)
-------------------------------------------
Seat tube range c-c: 52.6 - 53.1
Seat tube range c-t: 54.3 - 54.8
Top tube length: 56.2 - 56.6
Stem Length: 11.6 - 12.2
Average 56 + 12 = 68cm. I Cannot imagine riding a teeny little 55cm frame and moving the bars back 1.5cm total?

Here's what they're recommending for a TT fit.

The Aero Fit
-------------------------------------------
Top Tube Range: 57.9 - 59.9
Stem Length Range: 8.0 - 10.0
Saddle-Bottom Bracket Position: 73.2
Saddle-Pedal Position: 90.4
Saddle-Ground Position: 98.2
Cranklength: 177.5
Aero Bar Size: L
Saddle-Aero Bar Pad Drop Minimal: 4.8
Saddle-Aero Bar Pad Drop Moderate: 9.9
Saddle-Aero Bar Pad Drop Intense: 12.1
Saddle-Aero Bar Pad Drop Maximal: 15.8
Pad-Ground Position Minimal: 93.4
Pad-Ground Position Moderate: 88.3
Pad-Ground Position Intense: 86.1
Pad-Ground Position Maximal: 82.4
is any of this useful?

 

[frdfandc]

We just sold a Fuji D6 to a customer a couple of months ago. He normally rides a 61 cm road bike, and originally purchased a 58 cm, but it was still too long for him. He ultimately ended up with a 56cm.

I've seen with the TT bikes we've sold, that its at least 1 to 2 sizes smaller to get the correct positioning on a TT bike vs. a road bike.

Best bet would be to find an experienced Tri store and get sized professionally.

 

[stubek]

Hi all,
I have a spreadsheet I have been putting together for MYSELF for a couple months comparing about 30-40 TT frames (including several of the Chinese ones) in head tube, top tube, seat tube, stack, and reach. I have a coach who I work with for fittings. So, two important things from him that he would tell you are.
1. find the geometry that is right for you, then look at which bikes have that geometry (I can only ride a 51 Cervelo P3, but I ride a 54 Fuji D-6 and my normal road bike is a 54 Scott CR1 Pro
2. You want to get your arms to that 90 degree angle, and be comfortable. To do this, you will normally want to go to a shorter frame so you have more adjustability with saddle fore/aft position, stem length and height, and also the basebar/extension you select. He said that the base bars where the extensions come out level with the bar such as the Zipp Vulka are very aero in a wind tunnel, but normally force the riders into uncomfortable and unaero positions and thus loose their benefit. He said some of the pros he works with are moving away from the Vulk and Shimano Missile for that reason.

 

[draganM]

We just sold a Fuji D6 to a customer a couple of months ago. He normally rides a 61 cm road bike, and originally purchased a 58 cm, but it was still too long for him. He ultimately ended up with a 56cm.
I've seen with the TT bikes we've sold, that its at least 1 to 2 sizes smaller to get the correct positioning on a TT bike vs. a road bike. .

thanks, that's an important insight. My one concern with dropping down 2 or 3 sizes and using the long 175mm (or ideally longer ) cranks is the tip of my shoe rubbing the back of the f-wheel when I turn

Best bet would be to find an experienced Tri store and get sized professionally.

Yes but since I'm looking to (re) build my own I don't like to take up some shops time without buying there. Of course I could also pay them up front for the fit but I'll need to find a friendly TT shop in Boulder first.

Hi all,
2. You want to get your arms to that 90 degree angle, and be comfortable. To do this, you will normally want to go to a shorter frame so you have more adjustability with saddle fore/aft position, stem length and height, and also the basebar/extension you select. He said that the base bars where the extensions come out level with the bar such as the Zipp Vulka are very aero in a wind tunnel, but normally force the riders into uncomfortable and unaero positions and thus loose their benefit. He said some of the pros he works with are moving away from the Vulk and Shimano Missile for that reason.

I remember when they came out with these and they looked brutally uncomfortable and forced the riders wrist and forearm into a severe twist. IT wasn't the first time someone decided that Aero was more important than comfort , my Giant TT bike with forward sloping top-tube is from that old school. Like you mentioned though if your suffering from your position and squirming around your not going to be either aerodynamic or fast.
I remember slapping clip-on's to a cheap steel frame 20 years ago and that bike felt like something you could ride all day. The elbow pads on that one though actually extended back behind the handle-bars. I think that kind of TT bar made sizing the frame much easier but For some reason It's no longer in Vogue

 

[stubek]

I think that kind of TT bar made sizing the frame much easier but For some reason It's no longer in Vogue

From what my coach has told me, the method for a few years was to make the bike aero and conform the rider to the bike. This in the end became a less aero package than using a slightly less aero frame, but getting the rider more comfortable. One of the biggest places you see this is the stem, having it up a little higher often allows the rider to be more aero and comfortable than having it lower and having the bike be aero, but the rider so uncomfortable, they don't properly fit it.

But, its also very dynamic and differs with every rider.

 

[draganM]

One of the biggest places you see this is the stem, having it up a little higher often allows the rider to be more aero and comfortable than having it lower and having the bike be aero, but the rider so uncomfortable, they don't properly fit it..

I wish my biggest challenge was just stem height. My dilemma is frame size and most importantly top tube length. The problem I see with most set up's is
1) you size the frame small enough (short top tube) to pull the handlebars back far enough for the elbow-rests to be comfortable in the aero position. BUT
2) you wind up with a situation where when it comes time to stand up and accelerate the bike over a climb our out of a turn your knee's are now either kocking on the handlebars or uncomfortably close to them.
I spent 2 hours over the weekend with both my new road bike, my old TT bike, and a level/measuring tape. My current TT top tube is 533mm and if the tube wasn't sloping down in front it would be a comfortable lenght for aero position. However when I stand up on the pedals I encounter problem no.2 above. So this frame seems too small when your out of the saddle.
so i'm looking at the Leader LD-720 57cm with 551mm tope tube. Roughly .75 inches longer than my current set-up and top-tube would now be level. However with this frame I would have the elbow rests too far out. :idea:

I think my solution will be to go with the LD-720 57cm and modify my clip on's to move the elbow rests back anywhere from 1 to 2 inches behind the bullhorns. MAchine some custom brackets on the CNC during lunch and after hours. IF I keep the pads inside the swing of my knee's I should get both problems solved. I will post some pics of everything as I move along with this project and hopefully they will be intersting and informative for all the good folks here.
If anyone has pics or examples of this that was done previosuly to a bike then please post.

 

[stubek]

draganM,
Are your knees hitting the basebar or the pads? If it is pads, maybe elevate the pads just a little?
If it is the base bar, go for one of the ones that has a strong forward sweep to it and see if that helps.

Your solution sounds good also, I just don't have those skills or resources.

 

[draganM]

went with the Leader 720 in 57cm. Will know this weekend how it builds out but the geometry is very too close to my old Giant. A little too close actually but I can set the stem height anywhere I like it now as opposed to the giant which I bought used/ pre-built.
wish me luck

 

[ridenfish39]

We just sold a Fuji D6 to a customer a couple of months ago. He normally rides a 61 cm road bike, and originally purchased a 58 cm, but it was still too long for him. He ultimately ended up with a 56cm.

I've seen with the TT bikes we've sold, that its at least 1 to 2 sizes smaller to get the correct positioning on a TT bike vs. a road bike.

Best bet would be to find an experienced Tri store and get sized professionally.

^^^^^^^^^
Good advice

I ride a 60 cm Cannondale System 6, and I just ordered a 56 cm Cannondale Slice TT frame after a fitting sesion.