I’m 5’10’', but short legs (82.5 cm inseam) and long torso. I’m torn between two sizes, as the 54 option would be obviously lower, but I would have to use a 120 to 130 mm stem on it, similar to my road bike.
The 56 option would be higher, but would allow me to use more stem and cockpit options.
Maybe some ST’ers that have simial numbers can share their knowledge and prefferences for one or other frame sizes.
*** Save yourself from the “have a bike fit done first”, or “what are your pad X and pad Y numbers ?” as these kind of services aren’t available around here, it is out of my budget right now
My height and inseam are very similar to yours. I rode 56cm bikes for years in a variety of brands but my last purchase was a 54cm and I have been VERY happy with that – glad I went with 54 as opposed to 56.
I am going to be dangerous and say that without even thinking, I bet 54 is best for you. (aka: if between sizes the safer bet is to size down)
I am in a similar boat to you. no local fit options. I am also between sizes but 51/small generally does it. The frame you chose is important, but the front end is everything. If you are like me, you will likely be unable to sit on bikes to try them out. So it is all about geometry charts.
standover. Make sure you measure that with shorts on, and shoes on. That may rule out some frames already. This is key as short legs/long torso will skew you to larger frames based on your height for generic brand fit charts. They may direct you to a frame with too high a standover.
Front end: Start by choosing a front end Any bike with a decent front end (highly adjustable) should be able to accommodate your eventual fit. Until you find that fit, you want something easy to adjust with lots of range. My questions are “can I tilt the bars” and “what pad adjustment fore and aft can I get?” If a front end has limited pad adjustment fore and aft (the typical weakness of older front ends, as is lack of tilt options), your only option to improve fit is with stems… and that can be a pain in the ass if you want integrated aero stems as many have few options. Also, have fun adjusting your fit a few weeks, months, or years after getting the bike as our flexibility changes over time (I assume you are new if you are asking such questions). For a beginner, I think something like the felt bayonet 3 is a great option. Lots of stack options, lots of tilt options, and the armrest brackets are separate so you have almost unlimited pad positioning choice. They may have less “bling” cred, but it is a solid option until you sort out your fit.
I blindly say 54 because when in doubt, you can always make short bikes longer, and low bikes taller via the front end. The reverse is tough. Just make sure your front end can compensate if required.
Choosing a frame that a good lbs sells may help on the support end. Used is never a bad idea either. If you can find a local used option, chances are you get to sit on it to test basic fit, but remember that it is set up for someone else, so what you really care about is stand-over, and how adjustable the stem is, which can be done remotely. AKA: The bike will probably feel like crap for fit, and as it should as it is not fit for you yet.
Crank length: larger frames will size up the crank length, and tend to be taller for stack. For your short legs/long torso this is a double whammy to your fit. long cranks force a lower seat position, which puts more requirements on your front end in case you need to get lower. In short, larger frames will raise the front of the bike relative to the rear. this can potentially reduce front fit options as you may not be able to get as low as you wish up front.
How are you working out the optimum stem length for the TT bike?
You first want to work out how high you want to be and then work backward on the stem bar combo. On a TT bike (especially one with a 73+ degree head angle) you have two options for raising the bar in order to get the length correct. You can add spacers under the stem, like you would on a road bike, and let the head angle bring the bars back to you. Alternatively you can slam the stem and use spacers under the cups to raise the front end without altering the length.
If you do need a 130mm stem on the 54 to get the length with a slammed stem and pedestalled bars you need the bigger size. But it also mean you have a long torso for someone your size. Given your height I suspect either size would work without doing anything odd to the front end you just need to play with spacers under the stem vs spacers under the cups.
I’m a little taller at a bit over 5’11", but have the same short leg/long torso build. I had a 54 road bike that was perfect for me. My 54 felt B12 just didn’t have enough length. I had a huge stem and moved pads in front of the base bar. When I bought my Felt IA16, I went with the 56. Was so much easier to get a good position. However, the standover is about as much as I can handle. Luckily that’s not all that big a deal on the tri bike.
No I don’t.
I transformed my road bike as a TT bike to get a fit closest to ideal as possible. I can probably raise the cockpit a bit if I want to work towards long distance, but am comfortable to ride hard for an hour on this actual position.
Here’s what it looks like:
Top tube : (c-c 52.7 cm horizontal 54 cm)
Saddle height: 73 cm
Head tube: 140 mm
Head tube angle: 72°
Seat tube angle: 74° (should be steeper with the reversed seat topper and actual saddle position)
Stand over height: 771 mm
I can actually measure pads positions as is on the road bike to get a better idea I guess ?
