Sam123 said:Why?
There about £100+ lol
Well, I'm certainly not the arbiter of how someone else should spend his/her money ...
BUT, the short answer is that at the moment you are only 16, and I can't believe that you aren't going to grow two-to-six more inches than you currently are in the next four years. You are probably going to be at least an inch taller at the end of this Summer! So, the carefully structured fitting probably won't be valid sooner-rather-than later.
Now, if I had a lower back pain when riding, I would trundle off to the library to see if any of the suggestions in Arnie Baker's book (BICYCLING MEDICINE) work, first ...
OR, I would possibly make an appointment with a chiropractor and have him/her explain what I am doing incorrectly with regard to my posture OR if there is something I (meaning, you) could do to mitigate the adverse effects of a possible, underlying structural problem with my (meaning, your) body which is affecting my standing & sitting posture.
As far as frame fitting ...
Unless you get a custom frame, at your height you just need to buy the largest off-the-peg frame that you can buy ...
I think that the typical/standard Road frame will not have a top tube longer than 59cm ... that will probably work for someone your height, but (again) I can't believe that you aren't going to grow two-to-six more inches than you currently are in the next four years!
The OPTION which I would probably be looking at if I were as tall as you are (I'm not ... I'm 5'9"😉 would be to buy an X-Large Hardtail frame (yes, a MTB frame) which will probably have a 60cm-to-62cm virtual top tube ...
I think the ORBEA Alma was/is a CF Hardtail. SETTE is a sold-in-America frame "brand" which are undoubtedly fabricated in China ... the unlabeled equivalent can be bought through eBay & will be shipped Worldwide.
Then, I would put an ALPHA Q Road fork on it (see attachment for an example of a MTB frame which I converted with spare parts that I had) because it is what I already have ... BUT, initially, the fork from your Claude Butler will certainly work.
[INDENT]FYI. I needed to enlarge the non-caliper side of the fender/brake mounting hole on the seat stay bridge to accept a recessed brake nut & I installed a long reach Tektro caliper (front & rear). The "reach" on whatever Hardtail a person chooses might require a caliper with a longer reach OR a regular road caliper might work ... each frame is different.
[/INDENT]
The ONLY (?) problems with the configuration are that:
- the BB is probably about 6mm higher (I've never bothered to actually measure it) which isn't really a problem
- I needed to lace a road rim onto a 135mm hub
- I needed to use a 118mm spindle that is normally used for a triple to provide chainring clearance (the crank that is pictured is an ISIS, but I've subsequently changed it to an Octalink & 118mm Octalink BB) ... some MTB frames may be able to use a standard length BB spindle, particularly since 2x10 MTB drivetrains are now in vogue.
The longer chainstay is a bonus, IMO, because it really takes the edge off of road irregularities.
The higher BB takes about 30 seconds (or, less!) to get used to ... and, for a taller rider, it would expedite using longer-than-175mm cranks.
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As far as so-called professional frame fits, for the longest time, and presumably-and-possibly ongoing, the tendency is to position a rider using KOPS as a guide. Keith Bontrager (yes, the namesake for BONTRAGER components) discounts KOPS as the universal position for all riders -- I agree.
A young fitter might want you to have a lower stem/handlebar as a default position because THAT is how s/he has her/his bike set up ...
Or, an older fart may think you should set your bike up the way Pedersen of Rivendell thinks the handlbar/stem should be set up (i.e., more-or-less at the same height as the saddle, as I recall) ... echoes of how frames were fit decades ago.
One bike shop that is local to me which uses the super-duper, SEROTTA Personal Fit System SizeCycle gizmo & undoubtedly incorporate Serotta's philosphy tends to fit frames the way Pedersen suggests ...
People I know who have bought bikes from that shop rolled out the door with a bike that is probably one frame size larger than the rider might get from another shop-and-fitter using the same system.
Do their bikes fit?
Well, that's open to debate.
People who have bought bikes from that shop have subsequently tweaked the fit ... that's not uncommon, BUT one would think that it shouldn't be necessay if the professional fitting had been as meaningful as it is purported to be ... OR, you hope it will be.
Serotta's frame fitting gizmo (there must be others out there) can certainly expedite sizing a frame ... BUT, some of the fitting undoubtedly will incorporate the component choices which the rider thinks s/he should have ...
Two of the fore mentioned people arbitrarily (IMO) decided that they wanted to use 172.5mm cranks ... so, the fitting at the fore mentioned shop on the super-duper gizmo were based on 172.5mm cranks regardless of whether or not 172.5mm is the best size for each rider -- unlikely since one of the two is about 5'10+" & the other is about 5'8+". The guy who is 5'10" was fitted with a 58cm Kestrel ... the size frame that a slightly taller rider would certainly choose.
What's wrong with THAT picture?
BTW. The first bike I was sold by a bike shop (a long, long time ago ... before frame fitting was even a concept and even before gauging standover height as a basis for sizing frames) was a 60cm (!) Gitane ... I'm 5'9". Okay, back then, the top tubes were often the same length (~57cm), and the stem was the variable. 20 years earlier, they probably would have sold a larger frame to someone my size ...
Fortunately for me, what I now deem to be the accidental sizing actually worked for me because the particular frame size came with a 90mm stem.
My brother, who is about an inch taller than I am, had a ~53cm frame at the time because HE independently chose the frame size -- at the time, I couldn't imagine riding a frame which was THAT SMALL, but my current frames approximately that size!
Sizing & Fitting, at its best, isn't cut-and-dried ... and, for someone who hasn't finished growing, it seems as though you can spend your money in better ways.