Hello there,
Just bought a Giant Defy in M/L. Previous owner was 5’9″(175cm) and found it proper size. I’m 5’8″(173cm) and find it quite a stretch. First (being a newbie) I thought it was just me being unfamiliar with road bike geometry but reading forums became clear that an M frame suited me better.
My question is:
Would it be okay to swap out the stock 100mm stem for a 80mm one (or even the seatpost for a zero offset one) or should I sell the bike and get one with proper size?
I know it affects body position therefore weight distribution and steering sensitivity just don’t know by how much or if I could get away with it.

An 80mm stem would probably work OK, but I wouldn’t recommend going any shorter than that. At some point the steering may become too twitchy with a shorter stem. But it’s an easy swap and cheap to try it compared to swapping the whole bike.

Have you had a look at the giant sizing chart ? Not wishing to be negative, however I am 5ft 10 and on the chart fit firmly into the M Defy. I had a bike fit when buying and was sized on a M and a M/L and ended up with the M and a 110 stem.

If you have a long torso you may get away with a 90 mm stem, any shorter and steering may get unstable

Swap the seatpost first.

Get an inline seat post and move seat as far forward as you can. Wouldn’t recommend a 80mm stem.

Unless you are a T Rex, it’s too big. I’m 5 10.5″ (179 cm) and ride a Medium with a 125 mm stem. You can compensate with a shorter stem – I have done just this on my commuter, but watch out for handling.

DON’T fix reach issues my adjusting the saddle. Correct saddle position comes first, then stem length chosen for reach. NOT vice versa.

It’ll be fine – has much less of an impact on handling than on an mtb.

I’d move your saddle forward also.

Tired, how does one determine correct saddle position ?
Ps serious question

Saddle is as forward as possible and luckily it seems also the ideal position. With pedals leveled my forward leg’s kneecap is in line with the pedal axle. It’s just that 20mm I seem to miss. Just don’t know how much it would affect handling or with my weight being more rear biased how much discomfort would it cause.

Watch out for increased shimmy at speed with a short stem. Noticed this with a 100 mm stem on my TCR in a race this week.

I set saddle as toronte does, plumbline down from base of kneecap to pedal axle. Height is set with a 25-30 degree bend in the knee when pedal is at the bottom. I use a goniometer to measure this. Then handlebar height for comfort and finally stem length by placing hands on the hoods and looking at elbow bend. 100 degrees is my preference on the hoods.

With this method, I seem to reproduce the hub hidden by bars when hands on the top of the bars (but there is a lot of leeway).

If it is a high quality Defy, I’d swap frames, personally. Once frame fits properly, you’ll never go back.

Oh and I spent three weeks agonizing over whether to get a M or a M/L. Including an extended test (with race) on the M that finally swayed it for me. Since it’s an SL, once the seatpost is cut, there was no returning it, either!

Wow! I’m about your height and ride a small defy I could get away witha medium but small felt right.

There should be no problem switching down to 80mm.
My Cube had a 110 and i felt too stretched so changed it down to a 70.Everyone says twitchy steering but i think its actually improved the cornering.It’s also more comfortable.
Set your saddle position first as per knee position in Torontes post then look at the stem.Sit on the bike in your prefered position,not on the drops,and look down at the front hub.General advice is that it should be obscured by the handlebar-stem junction.On mine i can just see the front part of the hub,so maybe another 10mm may be ideal.
A friend with the same bike changed to an 80 and feels its spot on compared to the original 110.

Put a longer stem on for 2 weeks, and commit to riding it.

When you change back to the original it’ll feel just right.

You can train yourself to ride in a more stretched position without any hassle, you just need to go for it!

Do you ride on the hoods a lot ? Maybe position them higher on the bars so it is not such a stretch .I have put levers on bars to low in the past and repositioning them makes a big difference ,or if you dont use the drops much just rotate the bars a bit to get the hoods a bit nearer

i am same height as you, and a small frame was perfect but i could get away with the medium … a large medium would have been huge.

Its the height of frame as much as reach to consider.

You can also buy compact drop bars which bring the hoods closer in compared to other bars…

Decided. Selling it.
Thanks for all the help. Until I find a buyer I’ll try a 80mm stem and fiddle with other settings you’ve suggested.
Most folks my size are riding an S according to the internetz. Also Canyons fitting guide suggested an S(53) for me.
Another lesson learned. Don’t force it just because it sounds good.