frame size - contradictory advice

[markbh]

Been cycling for 20 plus years on same old trusty Peugeot basic road racer type drop bars 2x5 speed which is falling apart and so I'm looking to buy something roughly equivalent.

Frame size though.

Every shop I go in they tell me I'm probably a 54 cm. I'm 5'7'' tall.

Every web site I look at says to measure inside leg and then multiply by 0.65 (some say 0.67).

BUT the latter gives me an answer of c. 50 cm!?!

PS A cyclist friend reckons my old Peugeot was a 21" frame and was probably too big as I have seat and bars low. But I obviously managed ok for last 22 years.

Anyone know why I'm getting different answers or have any advice.
Many thanks

 

[shooter560]

I'm 5'10" and my bikes are 52 and 54, however I am slightly short in the legs and longer in the body, but I would say you'd want to be looking at 50 or 52. when I was looking at a bike I was also told larger but after some web searching and playing about I found for me the web specs were better suited to me.


Really depends on how a bike feels more than anything, get the frame right and all the components can be changed if needed to get a perfect fit for you.

 

[ufkacbln]

Take the old bike in and place it beside the new one...... then compare?

 

[ASC1951]

Every shop I go in they tell me I'm probably a 54 cm. I'm 5'7'' tall.

Every web site I look at says to measure inside leg and then multiply by 0.65 (some say 0.67).

BUT the latter gives me an answer of c. 50 cm!?!

Don't forget that 'inside leg' for those purposes = to floor, not to ankle like on a pair of trousers.

It depends on your relative leg/torso length, but I'm 5' 5" and can ride 50 or 52cm frames depending on how I set them up. I would expect 52cm to be a much better fit for you than 50cm. 54cm is a tad on the big side, IMO.

The final adjustments are made with stem length and saddle position. If you are between frame sizes, you are generally better going for the smaller one.

 

[RedBike]

It all depends on which make / model you're looking at. Just to be really helpfull everyone seems to measure their bikes differently. I would more or less ignore the seat tube length (espeshially with compact frames) and start looking at the lengths of the top tubes instead.

A 21" top tube is roughly 53/54cm.

 

[markbh]

Thanks for those thoughts.

Sounds like the old bike probably was a tad too big a frame and I'll maybe try a 52 or 50 next 'test ride'. Don't know why the shop assistants all suggest 54.

I notice that whatever the size my old bike had a very short stem (?right terminology) from the line from top of front forks to the h'bars and as such with my elbow just touching the front of the seat my finger tips just reached the h'bars. On all the new bikes I looked at (save for Pinnacle ones for some reason) this stretch or reach was much further.

Have to say I like the feeling of being quite compact and as I have a back problem I don't really want to be over stretching. I notice as well that you guys all ride with hands right forward over brakes whereas I mainly used centre pull extensions with hands cupped on the first part of the curve of the bars.

Ahh it's all changed. You don't even have the gear changers on the main frame any more!

 

[yenrod]

Been cycling for 20 plus years on same old trusty Peugeot basic road racer type drop bars 2x5 speed which is falling apart and so I'm looking to buy something roughly equivalent.

Frame size though.

Every shop I go in they tell me I'm probably a 54 cm. I'm 5'7'' tall.

Every web site I look at says to measure inside leg and then multiply by 0.65 (some say 0.67).

BUT the latter gives me an answer of c. 50 cm!?!

PS A cyclist friend reckons my old Peugeot was a 21" frame and was probably too big as I have seat and bars low. But I obviously managed ok for last 22 years.

Anyone know why I'm getting different answers or have any advice.
Many thanks

Mark, if I were you i'd measure the top-tube on the bike then see if you can find the angles, if you know them..then start seeking new bike.

Then - you pretty much have similar to what you've been used to.

Changing your set-up on a bike (if a shop will recommend a bike but will be of differing angles etc..) is not good; ive done it in the past but end up going back to what comfy/good for myself

 

[HF2300]

As has been said, the 'inside leg' when measuring is from tape firmly jammed in your crotch (as if sitting on a saddle) to the floor, not conventional trouser inside leg, so that may be one discrepancy.

I've found while hunting around that there's all sorts of differences. Different makers measure size in different ways, and modern 'compact geometry' frames are said to measure smaller than older styles. Modern bikes are built with 'proportional' frames (frame gets longer as it gets bigger) but older ones (your Peugeot?) weren't. The old style of riding was 'a fistful of seat post' showing, whereas modern geometries often show a lot more seatpost for the same riding position.

From my (admittedly limited) experience a GOOD LBS are reasonably good at judging to within a size or so just by looking at you, but individual differences (long or short legs or arms relative to torso, your own preferences as to seating position) may throw that judgement out a touch. I have the impression the online sizing guides are good for normally proportioned people, less good as you differ from the average. If you have the option, it's worth jumping on a bike a size smaller or larger than your nominal ideal size to get a comparison.

I've had doubts about some of the benefits of test riding but the one thing I am certain about is that it'll tell you what's the right size and what isn't. Use the information to dial in a rough size, try what you can around that size and go with what's comfortable for you.