Geometry comparison help

[Andrew_Culture]

As I whittered on about elsewhere I recently went for a bike fit and it turns out the farmyard gate I've been riding for two years is too large for me. I've spotted a Boardman frame on ebay for £100 that I really like on Ebay but to my eyes the geometry is quite far off what I need. Am I reading this situation right?

The Boardman frame is size LG and here's the geometry:

This is the geometry the bike fit folk said I should keep and eye out for:

 

[4F]

Going by that spec I would have said the medium was the closest fit

 

[Crackle]

It's too big.

 

[Mike!]

I'm far from an expert but isn't that fit chart showing a short Seat Tube for the length of Top Tube (517/557) ? My two medium frame roadies are both 54cm Seat Tubes? Medium Frame Boardman is fine for me and I'm 2" shorter than you? My guess is large would be ok but it certainly doesn't match your fit chart

 

[Pottsy]

Yes but the 517 seat tube on the fit chart is CTC for a sloping top tube design, so it's probably an actual of a cm or two more to the centre of a theoretical horizontal top tube.

I agree that MD frame looks closer to fitting requirement but I wouldn't do anything without sitting on both first. Who says your fitting recommendation is what you'll actually feel comfortable on too.

 

[mattobrien]

For £100 I reckon you could buy it and then make the differences match with stem length and seat post height. All depends whether it will be a temporary or long term solution.

You could also get the head tube height with spacers on the steerer post, possibly.

If it is going to be for the long term then it might be worth getting it more accurate, but on stem lengthy, you are only looking at losing c. 13mm to get it right. Was there a recommended stem length with the fit?

 

[Crackle]

I still think it's wrong for the following reasons.

Firstly that seat angle is going to alter the distance of the seat tube to bb (your top 164 measurement on your custom chart) by bringing it closer, meaning your seat would have to go back more to have your knees in the right position, thereby increasing the reach. On paper, it's a cm difference in length but it won't be when you've got the seat right, it'll be more.

It's a longer seat tube and a shorter head tube, so it's more arse up with a longer reach, it'll feel even bigger than the dimensions would have you believe.

Once again, it's too big by my reckoning. Someone feel free to correct me though.

Edit: Assuming your fit chart is correct, which I'd hope as you probably paid dosh for that, so having done so, trust it.

Double edit: On thinking more, you might get away with it but given you're coming away from one which was too big and giving you problems, I'd urge caution.

 

[4F]

It's too big, why pay for a fit if you don't follow what it says. Just say no.

 

[mattobrien]

With the wisdom being it is the wrong frame size, can I suggest looking at getting a Cyfac frame built to those exact measurements, you did have a fit with the Cyfac postural system after all

I am slightly in love with the XCR and they look better in the flesh http://cyfac.fr/xcr

 

[Mike!]

I've been thinking the same but didn't like to say.

Either that or don't know if they can suggest something close? I've not seen anything close to those measurements so maybe best to hold fire and save for the Cyfac? You've been riding the current one for a while after all!

 

[Gravity Aided]

Liking the Cyfac as well, Bespoke.(please excuse the pun)