TT frame sizing

Looking at an Orbea Chrono TT frame, but have never owned/ridden a TT
geometry frame. Only road geometry. I ride a Eddy Merckx 60cm road
bike with a 58.5cm top tube and 120mm stem (all c-c). I've been
professionally fitted to it, and have made some minor tweaks, so I
feel comfortable with sizing and fit for the Merckx.

The Orbea TT frame is XL: 60cm c-c seat tube w/ 59cm c-c top tube. For
a TT frame, I would like something shorter than a 120mm stem so I have
somewhat less weight over the front wheel. Given my current setup on
the Merckx, does it look like I should be able to get an optimal fit
with the XL Orbea TT frame? Do I need to consider other factors for a
TT geometry?

In article ,
AJ wrote:
Looking at an Orbea Chrono TT frame, but have never owned/ridden a TT
geometry frame. Only road geometry. I ride a Eddy Merckx 60cm road
bike with a 58.5cm top tube and 120mm stem (all c-c). I've been
professionally fitted to it, and have made some minor tweaks, so I
feel comfortable with sizing and fit for the Merckx.

The Orbea TT frame is XL: 60cm c-c seat tube w/ 59cm c-c top tube. For
a TT frame, I would like something shorter than a 120mm stem so I have
somewhat less weight over the front wheel. Given my current setup on
the Merckx, does it look like I should be able to get an optimal fit
with the XL Orbea TT frame? Do I need to consider other factors for a
TT geometry?

I would want to consider the seat angle and the type of handlebars.
You can't assume very much about the actual riding position on the
TT bike until you know where your elbows go.

--Paul

"AJ" wrote in message
om...
Looking at an Orbea Chrono TT frame, but have never owned/ridden a TT
geometry frame. Only road geometry. I ride a Eddy Merckx 60cm road
bike with a 58.5cm top tube and 120mm stem (all c-c). I've been
professionally fitted to it, and have made some minor tweaks, so I
feel comfortable with sizing and fit for the Merckx.

The Orbea TT frame is XL: 60cm c-c seat tube w/ 59cm c-c top tube. For
a TT frame, I would like something shorter than a 120mm stem so I have
somewhat less weight over the front wheel. Given my current setup on
the Merckx, does it look like I should be able to get an optimal fit
with the XL Orbea TT frame? Do I need to consider other factors for a
TT geometry?

I'm 6'2" and ride a 57cm TT bike so I can get the arm rests low enough.
Low enough being 7" below the seat height.
You may want to consider a frame that will give you this capability
after working on your TT position for a season or two.

Phil Holman

(AJ) wrote:

Looking at an Orbea Chrono TT frame, but have never owned/ridden a TT
geometry frame. Only road geometry. I ride a Eddy Merckx 60cm road
bike with a 58.5cm top tube and 120mm stem (all c-c). I've been
professionally fitted to it, and have made some minor tweaks, so I
feel comfortable with sizing and fit for the Merckx.

The Orbea TT frame is XL: 60cm c-c seat tube w/ 59cm c-c top tube. For
a TT frame, I would like something shorter than a 120mm stem so I have
somewhat less weight over the front wheel. Given my current setup on
the Merckx, does it look like I should be able to get an optimal fit
with the XL Orbea TT frame? Do I need to consider other factors for a
TT geometry?

I have found that for me at least, a similar cockpit length (top tube
plus stem) works on the road and TT bikes. In my case, that's 56cm
for the TT and 11cm for the stem (a very middle of the bell curve
bike).

But it's important to know the relative seatpost angles, since an even
steeper seat tube will require a shorter top tube, and a slacker seat
tube will require a longer top tube. In my case, the road seat tube
is 73.5 and the TT 78.0 degrees.

Another thing to consider is that a steep seat tube frame is taller
than a typical road bike "of the same size" because, well, the seat
tube is more vertical. If your standover clearance is marginal at all
on the Merckx, it's going to be negative on a the Orbea (if it's got a
seat tube in the 78 degree range).

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

AJ wrote:

Looking at an Orbea Chrono TT frame, but have never owned/ridden a TT
geometry frame. Only road geometry. I ride a Eddy Merckx 60cm road
bike with a 58.5cm top tube and 120mm stem (all c-c). I've been
professionally fitted to it, and have made some minor tweaks, so I
feel comfortable with sizing and fit for the Merckx.

The Orbea TT frame is XL: 60cm c-c seat tube w/ 59cm c-c top tube. For
a TT frame, I would like something shorter than a 120mm stem so I have
somewhat less weight over the front wheel. Given my current setup on
the Merckx, does it look like I should be able to get an optimal fit
with the XL Orbea TT frame? Do I need to consider other factors for a
TT geometry?

For the same stem length, aero bars normally put your elbows further forward
than for the same length of road frame and bars. You will need to try it
and see. Also take into account (if you will be riding any sanctioned
events) that there is a UCI limit of minimum 5cm between saddle nose and
bottom bracket and maximum 75cm between saddle nose and forward end of
bars.

FWIW, I ride 61cm or 63cm road frames with usually a 130mm stem, and a 58cm
TT frame (Cervelo P3) with Cinelli Angel bars. With the saddle nose the
minimum allowed 5cm behind the bottom bracket, I have the fore-aft
adjustment of the bars and elbow pads pretty much at the rearmost position,
and that just fits within the 75cm limit. I don't know offhand the top tube
length of the Cervelo, you could probably find out on their web site
www.cervelo.com.

Nick

I normally ride a 53 cm c-c road frame and have been sizing my TT frames
47-48 cm to achieve a proper position.

D




"Phil Holman" wrote in message
ink.net...

"AJ" wrote in message
om...
Looking at an Orbea Chrono TT frame, but have never owned/ridden a TT
geometry frame. Only road geometry. I ride a Eddy Merckx 60cm road
bike with a 58.5cm top tube and 120mm stem (all c-c). I've been
professionally fitted to it, and have made some minor tweaks, so I
feel comfortable with sizing and fit for the Merckx.

The Orbea TT frame is XL: 60cm c-c seat tube w/ 59cm c-c top tube. For
a TT frame, I would like something shorter than a 120mm stem so I have
somewhat less weight over the front wheel. Given my current setup on
the Merckx, does it look like I should be able to get an optimal fit
with the XL Orbea TT frame? Do I need to consider other factors for a
TT geometry?

I'm 6'2" and ride a 57cm TT bike so I can get the arm rests low enough.
Low enough being 7" below the seat height.
You may want to consider a frame that will give you this capability
after working on your TT position for a season or two.

Phil Holman