Bike size says it fits 5ft 7"-5ft 9", yet seat tube is only 49cm

rowanharley

I'm looking for a new bike as a 5ft 3". I found a frame of size 49cm yet the size guide says its recommended for 5ft 7"-5ft 9". Why is the top tube so small yet the size guide so tall? Also, is it ok for me to buy it anyways and what implications could I face after buying it?

StillGoing

RowanHarley wrote:

I'm looking for a new bike as a 5ft 3". I found a frame of size 49cm yet the size guide says its recommended for 5ft 7"-5ft 9". Why is the top tube so small yet the size guide so tall? Also, is it ok for me to buy it anyways and what implications could I face after buying it?

What is it? Bike sizing can be different from one manufacturer to the next. Are you sure it is a top tube length and not a seat tube length as Basso and Merida quote seat tube length in their size guide. I'm only a little taller than you and ride with a 52ish top tube length. Both bikes (Merida) are sized at 47cm.

rowanharley

philthy3 wrote:

What is it? Bike sizing can be different from one manufacturer to the next. Are you sure it is a top tube length and not a seat tube length as Basso and Merida quote seat tube length in their size guide. I'm only a little taller than you and ride with a 52ish top tube length. Both bikes (Merida) are sized at 47cm.

Now that you say this, the seat tube length is 49cm. Is that too high or will it be fine if I lower the saddle?

N0bodyOfTheGoat

What bike are we talking about? Link please.

My cycling inseam using the "book wedge" method is ~83cm, I set my pedal top to saddle top height at ~90cm. with that pedal crank running down the seat tube. The seat tube length of my Voodoo and Cube are quite different, but as they are two different styles of bike... The top tube length differs because the road bike increases the effective reach forward to the normal position on the handlebars, with a longer stem and hydraulic brake hoods that extend away from the drop handlebars

rowanharley

NitrousOxide wrote:

What bike are we talking about? Link please.

My cycling inseam using the "book wedge" method is ~83cm, I set my pedal top to saddle top height at ~90cm. with that pedal crank running down the seat tube. The seat tube length of my Voodoo and Cube are quite different, but as they are two different styles of bike... The top tube length differs because the road bike increases the effective reach forward to the normal position on the handlebars, with a longer stem and hydraulic brake hoods that extend away from the drop handlebars

This bike: https://www.planetx.co.uk/i/q/EBPXPEC13U/planet-x-ec-130e-rivet-rider-shimano-ultegra-6800-aero-road-bike

grenw

I'm 5' 8" and ride a small Canyon which fits perfectly. Very different bike but the seat tube on that it only 492mm so the same as the bike you've linked to.

Reach is very similar 376 (Canyon) vs 379 (PX) - 3mm in it. Stack is very different at 557 (Canyon) vs 526 (PX) but thats and endurance bike vs an aero one so I'd expect the PX one to be much lower at the front.

I think at 5' 3" you might be very stretched out and not be able to get the seat low enough. I know my wife at 5' 5" has ridden mine but has had the seatpost pretty much as far in as it would go.

Midlands Grimpeur

A 49cm seat tube is very unlikely to fit someone who is 5'3". You would want something closer to 43-45cm depending on the overall geometry.

StillGoing

Too big. I find it a stretch with a 530mm top tube length and I'm taller with short legs and a long body. Even if you were to drop the stem down to say an 80mm, it'd be a stretch. You probably need to look at something smaller or even forget aero geometry and look at something with a compact frame.

Something more like this which with a 47cm frame will fit someone 5ft to 5ft 4".

https://www.tredz.co.uk/.Merida-Ride-40 ... CEALw_wcB#

rowanharley

That's too bad now because it's hard to find an aero bike going that cheap with ultegra!

rowanharley

Actually I'm currently on a bike with a seat tube length of 55 so I think I may be fine on that bike. I'm going to measure out all the tubes and I'll come back with all the sizes and let you decide

webboo

I know you are only young but you still need to make the decision whether a bike is for you. Sometimes things just don't fit even if they are a bargain and if it don't fit then it's an expensive mistake.

rowanharley

Old bike/New Bike specs (mm):
Head tube: 110/125
Top Tube Effective: 530/530
Seat Tube: 580/490
Chainstay: 430/410
Stack: 550~/526
Reach: 400~/379
Fork Length: 390/370

StillGoing

RowanHarley wrote:

Old bike/New Bike specs (mm):
Head tube: 110/125
Top Tube Effective: 530/530
Seat Tube: 580/490
Chainstay: 430/410
Stack: 550~/526
Reach: 400~/379
Fork Length: 390/370

If you're 5ft 3" and riding a bike with a 530mm top tube length and find it both comfortable and aesthetically right, you must have an incredibly long torso and shorter legs than me, and your saddle must be so low down its virtually right on top of the top tube! Lots of us have made the newbie mistake of buying a bike that is too big, either because that was the only size available, or because we were so desperate for that model of bike and naively thought we could make it fit. Sadly you can't.

An aero frame is designed for speed. Its pointless buying one that's too big if you're not going to benefit from the design, unless you just want one for the looks and in which case you DO want the aesthetics to be right. But, its your money.

letap73

RowanHarley wrote:

Old bike/New Bike specs (mm):
Head tube: 110/125
Top Tube Effective: 530/530
Seat Tube: 580/490
Chainstay: 430/410
Stack: 550~/526
Reach: 400~/379
Fork Length: 390/370

Your old bike is (much)bigger than the bike you are looking at.
The reach on your old bike is pretty long - have you got the geometry of your old bike correct?

mfin

RowanHarley wrote:

Old bike/New Bike specs (mm):
Head tube: 110/125
Top Tube Effective: 530/530
Seat Tube: 580/490
Chainstay: 430/410
Stack: 550~/526
Reach: 400~/379
Fork Length: 390/370

Some measurements are very suspect, if one bike has 15mm more HT but 24mm less stack something doesn't add up properly (BB drop differences can't account for all that ...how are you measuring stack with your tape measure, a good detailed description?).

Then same ETT but 21mm difference in reach (STA angles would have to be wildly different on bikes that small).

Then there's fork length, so, do we assume you're comparing the new bike that has 700c wheels and the existing one has smaller? (hence it's angles might be wilder, such as STA).

I think the maths looks way too dirty and guessy here, that's my impression. I can't trust some of the measurements or at least am very sceptical.

I'd go back to listening to people talking about size for your height. OR... can you go to Planet X and sit on one, OR, find a similarly sized bike of another make and go sit on that?

rowanharley

The design of my bike is different to many others. It's a 1998 GT Force (I think) but it feels like it fits fine. My height is actually 5ft 4" at 16 although 1 inch probably won't make a difference. All those measurements are fairly accurate (rounded to nearest cm) but the reach and stack weren't accurate because I wasn't sure if I was measuring from the right position or at the right angle.

StillGoing

RowanHarley wrote:

The design of my bike is different to many others. It's a 1998 GT Force (I think) but it feels like it fits fine. My height is actually 5ft 4" at 16 although 1 inch probably won't make a difference. All those measurements are fairly accurate (rounded to nearest cm) but the reach and stack weren't accurate because I wasn't sure if I was measuring from the right position or at the right angle.

Ok I'm 5ft 6" and ride a 47cm Reacto as my main bike. That's a top tube length of 520mm, head tube of 109mm and a stack of 514. That fits me perfectly letting me slam the stem and have good saddle to bar drop to help with the aero position. If I rode the 50cm, which is closer to what you describe, I'd find it uncomfortable and would be wasting my money as far as the aero benefits went.

FRAME SIZES 47cm 50cm
TOP TUBE 520 535
SEAT TUBE 470 500
CHAIN STAYS 405 405
HEAD TUBE ANGLE 71 72
SEAT TUBE ANGLE 72-75 72-75
BOTTOM BRACKET DROP 61 61
HEAD TUBE LENGTH 109 124
FORK LENGTH 366 366
REACH 371 379
STACK 514 527
WHEEL BASE 974 978
STAND OVER HEIGHT 803 829

rowanharley

If it's any benefit, my inner leg is 75cm.

mfin

See the above comments by people even taller than you.

Going by your other thread about Planet-X, it seems you are fixated on this bike even if it's too big for you.

lakesluddite

Planet X do have a returns policy, so it should be possible to send it back if it were unsuitable - the only problem is you would have to stump up the return postage. Would the return postage be cheaper than a return train ticket to Sheffield? If not, visit them and throw a leg over one to make sure, and you can also sample the cultural delights of the Steel City while you are there.

diamonddog

I have tried this bike and at 165cm/5’5” with a 30” inside leg the seatpost needed to be cut to get the correct saddle height. I didn’t buy the bike as I was in the process of moving abroad but it was a very nice machine.