531colin wrote:If you want to tell me what size you would look at, i can look up tube sizes....chainstay length should be on Spa website?..........
Horizon, I'm just re-posting this, in case you missed it.
But....(sorry if I'm mis-remembering all this).....isn't it you who rides with a VK adapter (also known as a heavy great lump of metal) to get your saddle far enough back, and then has difficulty getting your drop bars close enough?
It would be a 54. And yes, that's me. On a 72.5 seat tube I still use a VK but the saddle is pushed forward
(a 72 might just do the trick). This is a supremely comfortable position: Brooks saddle, bum where I want it (i.e. not overhanging the back of the saddle), cleats spot on. And then the bars ... Actually a short stem and I'm fine but when I get round to replacing my Club Tour (it's an L size) it should be about right. I'm putting it all down to a long femur relative to height and a fairly rigid back. Mind you the bar comfort changes during a long ride from fine to "I wish the bars were just a bit nearer".
It must be good for me to review lots of my old decisions at once....its been quite interesting.
At size 54, all of the (steel) bikes have 28.6 top tube and 31.8 down tube (seat tube is common throughout)
all of the (steel) bikes have 22.2 x 0.9 chainstays, tapered/ovalised.
The Tourer and the disc braked bikes have 16 x 0.9 seatstays; the rim braked audax bikes have 16 x 0.7 seatstays....all tapered.
In other words, Aubisque frame will be just as stiff as Tourer, in the 54 size....in fact, Aubisque will be stiffer, as some tubes are ovalised.
And, I keep saying this, very little difference in the construction, and therefore weight of any of the frames....More difference in weight of the parts than the frames. In the big sizes, bikes designed with loaded touring in mind will have bigger top and down tubes than (say) the rim braked Audax bikes.
now for the interesting stuff.
54 aubisque chainstays are 435mm, 54 Tourer are 20mm longer, more chance of heel strike with Aubisque,
Aubisque front centre 605, ETT 565 (Effective Top tube)
Tourer front centre 625, ETT 577
But, Aubisque seat tube is half a degree steeper than Tourer, which equates very roughly to 5mm on the top tube;
SO....Tourer has 20mm longer front centre, but only about 7mm longer ETT....where has 13mm gone?
Answer; 9mm is fork offset, the rest is head angle.
Now to Horizon's fit.
I'm not sure about the long femur bit....KOPS is I think a useful rule of thumb for getting a fair proportion of people "about right" in terms of how much weight they put on the bars. '
I'm 71 years old and counting; I can promise you that as you get older you want less weight on the bars (ie saddle further back) and your stiff back doesn't get any more flexible. I'm assuming Horizon is younger than me, because most people are....but even if that's not the case, I think its daft buying a new bike or frame that's right on the limit of adjustment, right now....because whats comfortable will change. So, if we accept that your present riding position is "as comfortable as you can get it" I think you are shopping for a made to measure. Seat tube angle of 71 degrees will get your seatpost roughly 15mm further back than it is now.(10mm per degree) That should put you in the position where you actually don't have the saddle all the way back, and give a bit of wiggle room for the future. I don't know if Thorn still think their steering geometry is "state secret" material, but its quite easy to measure.
Measure front centre, reverse the forks and measure again. Fork offset is half the difference, as close as we need.
You can get an app for a smartphone to measure angles, it should be accurate enough if you apply some sensible control measures, like standing the bike on a level surface, measuring stuff at leas two different ways, checking the seat tube angle also.
The furthest I have gone is 60mm offset and 70.5 degree head, you can do a "back of envelope" calculation to see how much reach that could save you compared to the Thorn. (60 and 70.5 gives perfect stable tourer steering...if you need more off the reach, I would be happy to use 65mm and 70 degrees)
Then its just a case of looking at your favourite front centre dimension (is toe overlap a big issue for you?) and seeing if you can get ETT short enough.
(For example, if the Thorn is 54mm offset and 71 degrees, then 60 offset and 70.5 degrees gains you roughly 10mm)
A couple of asides...what seatpost are you using? long layback posts are not on every street corner!
If you move the cleats back so your feet come forward on the pedals, can you then move the saddle forward?
When you "wish the bars were closer" whats happening? Stiff neck/sore hands???,