Hello,

Looking at a new frame to build up - thinking this one. https://pedalforce.com/online/product...oducts_id=8420

Just a little confused as to which size I should go for.

I currently ride a 2003 Felt f50 - size 58cm. Which I feel is too big (73.5 angle 58cm top tube). I reckon the shop that sold me this one was keen to clear the bike out, and adjusted me to the bike, rather than put me on the right size frame. It has a very short stem on it to compensate. I am 178cm tall, 86cm inseam.

Just not sure whether to order the 55cm (which has a 57cm effective top tube - see the geometry), or the 52cm (55cm effective top tube). The 55 and 52cm measurements appear to be the actual measurement of the seat tube - which is shorter than standard geometry due to the sloping top tube.

My question - if I order the 52 (55cm effective top tube, 73.5 seat angle), is there any real problem if the seat post and stem is a bit longer? (as opposed to 57cm, 73 seat angle with a shorter stem).

If this makes any difference - I'm a light weight (61kg), so I go well up hills. A lot of my riding is time trials - in which I will put a forward seat post and tribars on the bike.

rabbit99, Welcome to the forum.

It's always difficult to fit someone over the internet because of all of the body variables. You need to consider the effective top tube and stem length you have now to make your decision. A long stem can cause odd steering feedback for someone with short arms. I doubt the seatpost length would be an issue.

Brad

What matters as much as anything is your actual saddle height and your preferred saddle to bar drop. Compare the total head tube length (with the headset) of you current frame to the proposed new model to figure out what must be done with the stem angle and spacers.

The 55cm has about 15mm less reach than your current frame and the head tube is 175mm, plus about 15mm for the headset. The 52cm has a reach that's another 15mm shorter and the head tube is 30mm shorter.

If you saddle height is around 76cm, to go with that inseam, then the 52cm would have a really short head tube, that would only be suitable if you can tolerate a ssaddle to bar drop in the 8-10cm range and a 30mm longer stem.

I just checked the current set up (set up for time trials).

The drop is about 13-14cm (measured to top of handlebars). Stem in 60mm. Frame geomtery for the old one is here ( https://gallery.roadbikereview.com/sh...89/si/Geometry ). The head tube is 160mm on the old bike - so my choice for the new is 175mm (would this be too high with the drop I have currently set up?), or 145mm. So my head tube can either be 15mm longer or 15mm shorter.

thank you for your assistance

You current stem is way too short, so you certainly don't a frame with more reach. The saddle to bar drop is quite large, although since it's a TT setup, that my be OK. The bigger question now is what are you setting this bike up for - road or TT? If it's road, then you don't want the shorter head tube.

the set up will be for mostly time trials - but with some road. Is the short head tube a big problem for road? Can I put more spacers in if I need to?