Bike Sizes - Bigger or Smaller?

Tim76

Hi guys,

I'm looking at getting a Giant Defy 0 and I have a query with regard to the best size.

I'm just about hitting 5'11" and my leg is just about hitting 33" also. So I'm just within the range for the M/L size.

However, a few people I have spoken to have recommended going for the M.

Any advice out there on whether it is better to go bigger or smaller when you are on the border of the two?

I have read that the smaller size would be more suited to aggressive racing while the larger would be better for longer less intensive rides, I would probably fall into the latter category but who knows down the line!

Any tips welcome

smacl

I'm 6ft and currently on a 2nd hand medium Ridley. Works fine but I had to put a long stem on it and have the saddle all the way back. Have a new bike ordered which is larger (56cm tt) and reckon I could handle a 58cm in the same geometry easily enough. If the frame is bigger than you need, and you use a shorter stem, the steering will be a bit more twitchy

Tenzor07

Have you been to a bike shop which sells Giant defy's?

Try them for size, you're definitely borderline m/l.

Either way, if you go for the medium and the reach or stack is not enough you can just put on a slightly longer stem or more spacers.

Cee-Jay-Cee

I'm 181cm and my height usually dictates a L or 56cm in most bike brands/models however a M or 54cm is more comfortable and suitable to my shape/size.

C3PO

Definitely the M/L IMHO! I'm also 5'11" and usually struggle to choose between a M and L - my M/L Giant TCR is the only one I have that fits me perfectly!

Tim76

Thanks for the responses guys. The TT of the Defy M is 54.5cm and the M/L is 56cm, 0.4cm difference in the reach and 1.9cm in the stack. Not too much in it to be fair. (to my untrained eye anyway!)

I've been to a bike shop that sells them alright and the guy said I could handle both sizes but recommended the M for serious racing and the M/L for endurance or more casual riding.

Kind of veering towards the M/L at this stage.

Lumen

The Defy is difficult to size down as the head tube is so tall.

I have a Synapse with similar geometry and had to slam the stem to get the bars low enough, and I have poor flexibility and core strength.

You must ride them.

torydiver

Mate rides a defy advanced size large. He's 6ft but very flexible, so no problem with reach, reckons he would be too cramped on a m/l.
I'm also just under 6ft , find his bike manageable, but would probably suffer on longer rides with it as being a bit stretched as I don't have his flexibility.
As mentioned, there's more to bike fit than tube lengths, angles, stack and reach etc,
a good fit Will also depends on flexibility, core strength amongst other factors....
Good luck with hunting, try as many as you can before buying....

Tim76

Cheers guys. Looks like a couple of test rides is the way to go.

Andy Magic

If you can squeeze onto a medium and your comfortable then go with that. I'm 6ft1 and was first sold a Defy in L it was way too big, I then got a M/L Defy three years ago and that fits perfect, I even have a 130mm stem on the front to get more aero on it.

I learned the hard way though I bought a Giant Trinity in L also and had to sell the frame. Always remember you can make a small bike bigger but you can't make a bike smaller.

Have you looked at the TCR at all? I just bought one in M/L recently and it's a lovely bike. But fitting for that was a lot more complex for me anyway.

manwithaplan

I'd tend to agree with Andy. You will probably have more scope for adjustment with the smaller frame. If you haven't been riding that long, it's likely that you will want to get a bit more aero over time. That makes the test ride tricky in that you might find the bigger frame feeling more comfortable and secure now but it could leave you with nowhere to go. Having said that, obviously don't roll out of the shop with something that feels like torture to ride.

If you have been riding road bikes for a while and are unlikely to be fiddling with your position, just go with what feels best.

gambeta_fc

One thing to keep in mind with sportive/endurance focussed geometry like the Defy is they tend to have a sloping top tube leaving a fair amount of seat post exposed to give a bit of flex.

I'm 6'1" and ride a Synapse, was going for a 56cm frame originally and could get the stack/reach that suited with a longer stem but with the saddle height set to correct level after a bike fit I was bang on the minimum insertion marker on the seat post. Might have been ok but played it safe and went up to the 58cm.

I have long legs though, someone else the same height wouldn't necessarily have the same issue as proportions can vary quite a bit. Your best bet is to try both.

68 lost souls

As well as the frame size you also want to take into account the width of the bars, the crank length and the stem. Which will suit you better in that regards.

Tim76

Well lads. Just back from the bike shop. Very little between the 2 sizes, one of the guys in the shop reckoned M/L and another said the M but I could ride either.

Anyway, took em both for a spin and tbh the M just felt that little bit better. Don't know why, just did, so I'm gonna go with that.

As was mentioned earlier in the thread there's always scope to up size the M if need be.

Cheers for all the advice!

torydiver

Good luck with it,
post a picture whenever you get a chance