New / old Cyclist Road / MTB / Touring Bike fit

[grarea]

I have been finding it quite interesting actually.
I have learned a lot.

I think the key to everything is that fore aft bit.
Getting your correct centre of balance / femur length right.
Then work from there. This is all about seat tube angle and setback.

The thing that I have discovered is that most (well, all nowadays) are around the 73/74 degrees.
A frame maker said because that is how the front mechs are designed.
Then they make the top tubes equal an average size as well.

So, there isn't a whole lot of geometry to try.
I think i need to go back to the eighties where they had more like 70 degree seat tubes.
I have ordered something else to try to see if I can find my sweet spot and then i will know where i am at.

I am more convinced that I have a longer femur (which pushes the seat back)
(Which is why all of my weight was on the bars. Try moving your saddle forward about three or four inches,
you don't support your weight on your feet which is what is happening to me.)
The trouble I will have then is my short reach, but it will be less important when I am more centred over the BB.
(I think)

I am real tempted by the bike fit idea, but if the chap is 19 and it is run by specialized, they will only know 73 degree sta.
I suspect that they are given formulas to work with.
It could be expensive.
The one nearest to me is a Specialized one, the next nearest is a Giant one.
They will surely be geared around the bikes that they sell.

I am more and more seeing why some people get a custom frame.
I bet a large proportion of people don't fit into that middle category.

 

[mattr]

I bet a large proportion of people don't fit into that middle category.

You'd lose that bet

Something like 97% of people are within the fairly small band around the nominal dimensions (given their height) and can be fitted to a bike with nothing more significant than moving the seat up and down/fore and aft and a similar adjustment to the stem length and height. Even allowing for flexibility issues and injuries.

The 3% either have more significant flexibility or injury issues or are outside the nominal band where fitting is straightforward. Most of those can be fitted by using odd seatpins (more set back, or offset) pedal spacers, swapping cranks, using funny bars or stems and so on. Or maybe looking at a different brand/model.

The vast majority of people getting custom frames are only doing so as they can't get exactly what they want off the shelf. The geometry is generally nothing special, it's things like custom paint, extra bosses, mudguard clearance and so on that they are looking for.

I'd be interested to hear which frame maker said that seat tube angle is driven by front mech design though. As with a braze on you are pretty much free to go from anywhere between about 70 and 77. Pretty sure the band ons allow quite a range of angles as well. (Though i've not read the latest requirements). And the most critical angle is actually the one between seat tube and seat stay.......

 

[grarea]

LOL, yup, caught me out there.
I definitely worded that wrong didn't I?
I agree with you.

 

[Woz]

Re:

Yup, any frame builder who builds custom around a technological brutal FD is a joke.

Bernard Hinault had a long femur and over the course of a few years tweaked his seat angle slacker and slacker. In his later years, the
man looks like a god on a bike.

Custom should really equate to tailor made. You state the purpose of the bike, sit on a special jig, tweak, measurements taken, then the frame is built. A experienced
fitter could take one look at you
on any bike at hand and start from there.

Specialized have all sort of gizmo body geo laser ball ache yawn fest scanners like at airports - which in theory
the 19 year old is able to do a
bike fit. God help you if you want
to learn and discuss with a computer.

An old artical about KOPS by Keith Bontrager is well worth reading with a good large whisky.

Lucky for me Norba classic 71/73 with a healthy offset post and long top-tube, 110mm stem fits like a glove to take up my monkey
long arms without being cramped but
still having a lively ride.

Having said that ancient 72 degree parallel is also good on agressive short rides.

 

[grarea]

Well, this has been an interesting few weeks.
I have been reading a LOT of stuff.
I can see why someone mentioned custom fit frame instantly.

When you look at the geometry of frames, they are basically all the same.
They fit the same ratio of body proportions. (Which I completely understand, who wants to make a frame that only fits 2% of the population?)
When you get excited about something, they just take it away somewhere else to make it more 'normal'

I tried to make my 74 degree sta fit, but i can't get the seat far enough back for what seems to make me comfortable.

It really has been interesting reading about it.
You have to be careful how you read what people say don't you?
You can tell who fits within the certain criteria.

OK, so, the key for me seems to be STA.
I have what i think is a 72.5 degree sta with a 2.5cm set back seatpost.
If I then sit myself another inch and a half further back, everything makes sense.

It seems to me that for a decent fit, the STA is crucial.
A mixture of personal preference, femur length and body weight distribution (centre of gravity)

I have looked at others comments and kind of compared to what seems 'normal'
I have short legs for my height, so i need a smaller frame but i have long femurs.
(The norm for small frames is to steepen the seat tube angle).
So, it turns out that I have pretty short arms, and so I want my seat right back but then can't reach the bars so need a short top tube and / or long head tube.

When I sit off the back of my saddle, suddenly it all makes sense. I have more strength when pedalling and my hands become really light. I can then kind of have all sorts of hand positions wheras until now I have been basically holding my body up.
I got a set of really adjustable bars and boy oh boy, the huge reduction of hand pain is completely luxurious.

 

[grarea]

The problem now is to work out my next step.
My original plan was to get an old mtb frame and swap wheels out to cover road and rougher track type thing.

But having been out and about, I really fancy disc brakes.
I would love to get a bike fit, but 'bike fit' seems to mean, bring the bike that fits you and we will make it fit.

I am on a tight budget as well.
So, my LBS is a good guy, but i can't afford a new bike and I would love to try a frame that is lower sta than 72 degrees.
But they don't exist new.
There is a specialized jig being set up in a month or so which hopefully will go back more than 72 degrees.
But the trouble is, they are all new to it, so, as you say, i would be having a conversation with a pc.
Might be worth the £120 though if i can fiddle with it.

I would like to find someone with a jig AND some experience.
Maybe I will have to travel a bit.

Any suggestions?
I am in Truro.

 

[mattr]

This is the old crap bike fitter thing. Making what you've got work.

A proper fitter with a proper jig will be able to fit you and tell you what you need to buy.

 

[grarea]

This is the old crap bike fitter thing. Making what you've got work.

A proper fitter with a proper jig will be able to fit you and tell you what you need to buy.

Nicely put.
Somewhat more succinct than me.

Nice to hear that they exist.
Now to find one. (any thoughts?)

I reckon I would save the £120 back by not buying bits and bikes to try.
It would be quite fun to hire a jig with a power meter wouldn't it and just fiddle about with it.
(oh and a HUGE selection of saddles )

 

[grarea]

I thought that I would finish this thread off with the conclusion.

Well, I thought that I would test my theory.
I took a huge chance.
I (disappointingly) picked up a new bike.
I got a Specialized Roll.

I was erring on the side of disc brakes as well anyway (some short sharp hills here).

It has a 67 degree STA and I nervously set out to find out if i had wasted my money.
Nope.
Well, unless it is solving an issue by the longer head tube (which might be the case),
I think it has done it.
My hands are instantly lighter, zero hand pain. The length of the top tube hardly seems to matter.
I can support myself when i lean a pretty long way forward now, rather than not at all.
I have some really adjustable bars so I can muck about with hand position loads.
The numb feet have disappeared and the sit bone pain has almost gone. (still a little work to do on saddle shape and HTFU)

(I changed the space shipped sized saddle out for what I had on before and also put the same wheels on to compare like for like)
The saddle is still at the back but i haven't the need for a setback seatpost.
I have definitely got more power. I can get up the hill with a harder gear (From a 22t to a 32T front ring). I can put the strength into the pedals.
I don't feel like I am constantly kind of falling forward.

All of the theories that you read about bike fit now work for me.
I can now cycle without being in agony after ten minutes. Yippee.

I can at last do some miles and see where to put my handlebars and tweak away.
Smashing.

Pretty disappointed it isn't a retro, but there you go.

Although I am pretty sure I can put my retro brake levers, maybe thumbies, maybe crankset, maybe derailleur.......

On the plus side, it does do what I fancied in an ideal world which was muck about with different wheel sizes. I threw on my 26er wheels and can use 700c for the road.

I will be interested to see where i am in a couple of years.
I will be able to see if i was completely wrong.

Thanks everyone for your inputs. It has been interesting.