I am in the process of purchasing a new bike. Local bike shop is having a great sale. I am currently ride a Softride Rocet TT. And I just don’t like it. I have broken it once and the beam is alway working loose. Before that I had a Lightspeed Tachyon. So for the last 5 years I have ridden only a time trial/tri bike. My Softride is a medium and my Lightspeed is a 53 cm.
So I am training for an ironman and I decided I need a road bike to do most of my training miles on. I am actually thinking of just moving the seat forward and putting on some Syntace clip-ons and using it for racing as well. So I go to look yesterday and instead of getting measured and fitted (which I have done in the past) I decide I am just going to try a couple of sizes and see which one fits the best.
I start with a 54 cm and it is way too small. I ride a 56cm and it is too small as well. ( when I rode it I felt like I was over the front wheel, and it had a 120 stem on it). Then I ride a 58 cm and it felt good. Very comfortable, very balance and very smooth. But here is the kicker… I am 5’10 with a 29.5 inseam. My torso is very long. I think that may be why it was so comfortable. I could still pick up the bike standing over it, and the wheels were about 1.5 inches off the ground.
I am looking at Treks.
My question is this. Is it conceivable that I would ride a 58 cm road bike and a 53cm tri bike? I just want to make sure before I purchase a bike.
A couple of things. First, you measure the bike by fit, not the number that is on it. It doesn’t matter if it says 53 or 58, what is matters is that it fits.
Next, a sale is not a deal if the bike doesn’t work. Take your time and get the right bike.
OK, you are used to riding a TT bike, which is perfect for any IM, so now you are training for an IM and you are switching to a road bike? That doesn’t make sense to me. BTW, I have done 12 IMs with all my riding and traing on either my TT bike, or my mountain bike. My TT bike is perfectly comfortable no matter how long I ride.
Lastly, I think you need to slow down and get some good advice for YOU. The next time I make a big move I am going to go see someone like Tom Demerly im MI. May not be the lowest price, but could very well be the best value.
Don’t worry about the height of the top tube, other than you can comfortably stand over it. The main measurement you need to be concerned about is the length of the top tube.
One of my training partners has the same build as you do. He has always had trouble getting bikes to fit. He looks at specs pages all the time trying to find the longest top tubes. That is what you need to be checking. I can’t give you measurements on any bikes, but I will say that for road bikes, the Giants tend to be long. With the compact frame, you can get a longer top tube without the height of the top tube being a prohibitor.
TT bikes usually have a lower top tube height so the head tube can be shorter, allowing a lower aerodynamic position. You really cannot compare them to a road bike. Also, most tri bikes also have a longer top tube, allowing the front wheel to be positioned further out, improving handling in the aero position.
Again, because of your long torso, you need to pay attention to the top tube length. Example Cervelo Team 58 is 575mm, Cannondale CAAD7 57 is 568mm, Giant TCR Large is 585mm.
I have heard that trek road bikes, their sizes run large… Something to do with how they measure the seat tube… I think the measure C-t causign the numbers to be a little bit inflated… adn no it is very common to have a road bike which is larger than a tt bike