I got the same geometry chart as cyberknight when I Googled "2010 boardman team carbon geometry"; doesn't link to a Boardman page mind you but a
2013 review, so note it may well be wrong! But until we know for sure for this post we will assume it is; using the 'Medium' size and cyberknight's 69cm saddle height:
View attachment 399005
Although I'd like frame 'stack and reach' as well handle bar 'reach and drop' for accuracy, which sadly they don't list, I can at least compose a
BikeCAD drawing using what they have listed, then filling in the gaps with a guesstimate.
View attachment 398947
'Jandn1' mentioned an inside leg (I am assuming crutch to floor) of 30"=762mm, using the traditional 88.3% of inseam formula as
starting point that equates to a saddle height of 672mm; that would start to be a bit low for this 53cm seat tube bike; it will be even worse on a 54cm that the seller has listed. But, the 88.3% as a starting point is all it is though. What you normally focus on is a leg angle; the shoe size, ankling and pedaling action all play a part in influencing leg angle and the required saddle height needed to achieve that. It would be normal for someone with an identical 762mm inseam with large calves and size 10 shoes to have a different saddle height to someone who has slim calves and size 7 shoes. This is because the foot pedal interface would differ between sizes and each rider would intuitively maximise their unique muscle groups; the rider with larger calves will often 'ankle' slightly higher than a rider who was more 'quad' focused for example; there is more to it than just inseam x 88.3%.
There is always value basing a new bike on the 'bike fit' of your current bike, providing your current 'bike fit' is correct of course. You may be surprised how many actually end up requiring a different size bike to what they thought they needed after they have got their position sorted. In this instance we don't know for sure the exact geometry of what is being considered of course, hopefully the seller will be able to clarify, especially as the above chart does not actually have a 54cm seat tube, although if it is one of those on that chart potentially they had measured the seat tube
to the seatclamp and not
including.