55.5 or 58.5?

charliew87

On the brink of buying a Giant Defy 2.

Went to a shop and sat on a few yesterday. I'm 6'00" exactly, 34" inside leg. Sat on 56 & 58 Spec Allez, obvo the 56 felt slightly smaller. I have no idea what the real difference is.

For the Defy 2 the options are 55.5 or 58.5? What do you reckon?

Wirral_paul

Really, its the one with the correct top tube length that will be right for you. You'll get the saddle height right on both equally well, but its the effective top tube length that will ensure the bars are in the right place.

Does anywhere local offer bike fitting with that bike?

Nairnster

what height do Giant recommend you use?

Also, try calling a reputable giant dealer, they may be able to offer some advice as a guideline, as they will have sold bikes to people of your height.

charliew87

Just rang someone and had another look online.

The Defy 2 55.5 has longer top tube than the Spec Secteur 56, and that is the one reccomended for someone of my dimensions. Apparently.

anto164

the 58.5 will be massive!

I am 5'11" and ride the 53.5 (ML) Don't forget it's compact geo! I will say i'm 100pc sure the 58.5 will be too big. The 55.5 will possibly be on the large size too.

One of the guys i know rides a 58.5, and he's 6'7"

Nairnster

Would say after that you may be able to find a L size under the £600 you are looking for

ChrisSA

You can make a small bike bigger with longer stems/setback seatpost.

You can't make a big bike smaller.

charliew87

I've tracked down both the 55.5 and 58.5 for £550

I'm going to go for the 55.5ML i think, judging by a google theres a lot of people in the 5'9" - 6'1" area who are dead happy with that size.

Plunge: Taken.

Peddle Up!

anto164 wrote:

the 58.5 will be massive!

I am 5'11" and ride the 53.5 (ML) Don't forget it's compact geo! I will say i'm 100pc sure the 58.5 will be too big. The 55.5 will possibly be on the large size too.

One of the guys i know rides a 58.5, and he's 6'7"

I know manufacturers' sizings differ but at 6' 3" I found a Trek 2.1 58cm too small and I needed a 60cm which fits me perfectly.

gmacz

55.5 will be perfect for you.
I am 6ft 2" and went for the 58.5 or xl and it is a full 58.5 and not equivalent.
Large was perfect fit for me.
Xl leaves the handlebar higher in relation to seat height, I think, this is why I went for the bigger bike.
Xl is still within my range.

charliew87

Christ this is confusing!

I've told the people who have the 53.5 and the 55.5 to hold them til tomorrow. Going to try some in London tonight.

The measurements seem very small, 3mm here, 8mm here. When I tried some Specializeds at the weekend I could barely notice the difference between the 56 and 58.

Can someone confirm that if I get a 55.5 and my technically correct size is a 53.5, that my legs wont fall off and I won't die an agonising death due to back pain?

vorsprung

I am 6'2" and according to my spreadsheet of "possible" bikes when I was looking at which new one to get, a M/L was a possible.

The two important dimensions on modern bikes are the top tube "virtual" length and the head tube length. The top tube "virtual" is the length if it was horizontal to the ground, which it often isn't. Often the top tube slopes.

In simple terms the top tube is the "length" of the bike for arm reach and the head tube is the "height" of the bike. There are added complications. For example the figure for the headtube usually includes the stack height of the headset. On a integrated headset this is very much smaller than a non integrated headset.

A useful figure for bikes that are supplied built up is the "standover height". This is the height of the top tube for practical purposes to the ground. If you lean against a wall, stick a book between your legs, wear cycling shoes and then measure the top of the book this and add 2cm will give your own standover height.

Having said all this the best thing to do is to go for an extended test ride

charliew87

Mind changed again. Went to a cycle surgery shop and then measured myself on competitivecyclist.com and both told me to get the 55.5. And that I shall do tomorrow.

Admin over. Cheers for help.