Trobinson986

I’m new to cycling and I recently purchased a giant TCR advanced disc. I am just barely under 6’1” tall. The shop sold me a size Large. Is this the correct frame size?

also, how do you actually measure the frame? I was told a giant size large is a 58cm frame. Where is that 58cm actually measured from?

Brofessor

58 cm would be the horizontal top tube length. It is distance C in the geometry picture towards the bottom of this site: https://www.giant-bicycles.com/us/tc...o-compact-2021 Not very easy to measure yourself, but size large seems right for your height, unless you want a really high drop to bars for a more aggressive fit.

shelbyfv

Nice bike, size sounds right, enjoy it!

trainsktg

I am 6'1 and my TCR is an M/L. But my Defy is an L. And my Revolt is an M. If it feels too big it probably is (a test ride of an L Revolt told me that). Otherwise its probably OK.

Keith

y2zipper

At 6'1 you have an overlap size. That means that a M/L or an L can both probably be adjusted to fit you. M/L would be more aggressive geometry, L would be more relaxed. I'd say test ride.

Squeeze

I'm a little over 6'1" and ride 58cm road bikes, if that helps any.

Danhedonia

I think sizing is more personal; I have a Giant TCR-1 (an '06) that says "L" and the size is 56. I'm 5-10, but can't ride anything smaller without having comfort issues.

Height is far from the only significant stat. Are you long limbed? That will definitely change what you find "fits." And some people like to feel more stretched out on a bike, some like to be in a more compact position. As always, YMMV.

If the bike feels too big, than perhaps it is. For you. Play with the seat position, adjust the handlebars, see what you come up with.

veganbikes

Are you comfortable on the bike (or relatively so) then probably good if it feels too big or too small than probably not so good.

When this whole pandemic is over you should find a fitter to help you set the bike up.

Trobinson986

Yes I am long limbed. My inside leg measurement is a solid 34 inches.

y2zipper

I agree here. I hate that size charts only use height when there are so many other considerations precisely because of overlap.

Trobinson986

I took it to a professional set up. It turns out my legs and arms are quite long relative to my height. I wanted to lower the bars for a racier fit and had to get shorter cranks to accommodate so because with the 175mm cranks that came on the bike my knees were coming too high to my chest at the bar height I wanted. I put 165mm cranks on. It should help increase my cadence also which I think will take load off my knee (I was having some left knee pain which we seems to have determined in the fitting was because my saddle was too high and I tend to lean to my right so I think I was over stretching the medial side of my left knee)

shelbyfv

6' with 165mm cranks Your pro fitter has some unique ideas for sure! Hope it works for you

Trobinson986

After changing my crank length from 175 to 165, my highest gear seems much more difficult to push. Does this sound accurate to you guys?

also, regarding your comment on 165mm cranks for my height- is that bad advice?

scott967

Yes. It's a lever so for a given force at the pedal, shorter lever arm, less torque.
Don't know, but 165 for a six-footer is uncommon to say the least.

scott s.
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Trobinson986

why is it uncommon? Please share your thoughts

shelbyfv

I'll let someone else explain the "why" but generally 165mm cranks would be used by someone in the 5' range. XS or under 50cm size bikes might come with them. Large bikes come with 175mm because it's an appropriate size for most who fit that size bike. Obviously there are outliers. Your "pro" fitter seems to think you are really outside the norm. Hopefully he has a reason, but anyone can claim to be a bike fitter and there are plenty of crackpots around. You have the cranks on there, might as well give them a try. Keep your 175s just in case.

Brofessor

There are two things to take into consideration when making a crank arm adjustment: 1) How high the knee is during the upstroke (this is what you fitter focused on) 2) Where your feet is on the pedal given the comfortable fore-aft position of the saddle. It is going to be almost always a compromise between these two aspects of a fit when you decide on a crank length. With a shorter crank length, you might have more comfort during the upstroke, but you feet will be farther forward on the pedal. If you are not a toe-dipper, this is not an issue. But for people like myself, who dip their toes during hard efforts, having your feet too much forward on the pedal will reduce power output as calf muscles won't be engaged as much. Another thing to consider is the rotational speed of your feet. At the same rpm, your feet will be going around faster with a shorter crank, which might require some getting used to. It's true that you would need a bigger force on the pedal to generate the same torque on a shorter crank, but the differences are usually largely offset by the comfort gains from a proper crank length.

Trobinson986

I went to a “reputable” place and he sort of urged me towards 165mm cranks. I wanted to lower my bars but I couldn’t really lower them much with my 175mm cranks because I was “bouncing” too much. As in my knees were coming too close to my chest as the fitter put it. He’s 5’11” and rides 165mm cranks. I considered 170mm but for whatever reason he sort of seemed to lean towards 165. He had to order them either way so it’s not like he was just trying to sell me whatever was in the shop. Do you think I made a mistake doing that short? I went for a ride tonight and definitely felt the difference. I had zero knee pain whereas with my 175mm cranks I was having some knee pain

y2zipper

If you had pain and it went away, that's probably a good start.



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shelbyfv

Update? Curious how the 165 cranks are working out.