Fit question stretched out on the hoods

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MikeF
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Re: Fit question stretched out on the hoods

Postby MikeF » 26 Aug 2014, 11:06pm

The conclusions from this thread seem to be
a: For taller people the problem is saddle setback. Shallower seat tube angles help overcome this problem but do necessarily eliminate it. Reach is not usually a problem
b: For shorter people the problem is reach to the handlebars and standover height. Smaller frames tend to have steeper seat angles to try to reduce the stretch to the handlebars. However this means that KOPS isn't achieved unless the saddle is set further back, thereby negating the steeper seat angle, and still leaving exactly the same problem with reach.

I prefer drops to straight bars as these tend to hurt my wrists and arms over long and /or rough journeys, but I seem to have similar problems to Mark with drops - no doubt as I'm a similar height. On one bike I have a 4.5cm stem (I don't think any are made shorter than that) and on another a 7cm 40 degree rise stem, which because of the rise is short, both with compact bars. I don't suffer from back pains or any other pains of significance, but I find that I am always slightly stretched especially when I set out - maybe it's good for the physique. :lol:

Bicycles have been around for over 100 years but still the problems of fit haven't been solved! Is it because frame design is now stuck around the use of 700 wheels and proportionate smaller frames cannot be made? Is the problem caused by drop handlebar design? With older bars the hands were behind the steerer, but with modern bars the hands are in front. Do you need a stem at all to attached the bars? Anyway I think with current bicycle design shorter people will always have a problem of bike fit, and will not match the stance of Colin in the picture - but maybe I'm wrong? :wink:
"It takes a genius to spot the obvious" - my old physics master

reohn2
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Re: Fit question stretched out on the hoods

Postby reohn2 » 27 Aug 2014, 8:11am

MikeF

The saddle position is sacrosanct for an individual rider and KOPS is a good starting point to fine tune saddle position IMO,as it's a tried and tested starting point if not the ideal.After which the ideal reach for the individual rider is found by h/bar style and stem length.
I'd agree that some people aremore flexible than others for whatever reason,spare tyre,not used to bending due to lack of exercise and or sedentary work,etc,etc.
The reach problem is solved easily by bringing the h/bars closer to the rider,achieved by shorter stem and or compact drops,or less frame in front of the BB,of course with 700c wheels this can create a problem with toe overlap this can be helped by a slacker headtube and or more rake to the fork,which in turn leads to slower steerering which is no bad thing.If still a problem a smaller wheel size 650b or 559, unfortunately such frames are limited not mention rim and tyre choice tyre choice.One other point is that as a general rule shorter legs require short cranks which again pushes the saddle further back making the problem worse.
Due to manufacturers not understanding the problem but catering for Mr&Mrs average the problem remains a real one people at either end of a four frame sizes across the range,world.
One thing's for sure over steep seatube angles at either end of the frame range size aren't the answer.
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531colin
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Re: Fit question stretched out on the hoods

Postby 531colin » 27 Aug 2014, 8:20am

All the while the bike buying public prioritise fashion and form over function and comfort, then shorter people will be penalised by bikes that are too long.
Thanks to the fashion for using round-the-world load-luggers for a 10 mile potter through the lanes of Southern England, some people will now buy small tourers with 26" wheels, so its dead easy to fit a 5' tall person with a bike with drop bars, toe clearance and a short reach.
People get their "information" to make decisions about buying "light" bikes from internet fora, and ill-informed cycling journalists.
So you get a whole world of bikes with 700c wheels, 45mm offset carbon forks and head angle 72 deg or steeper, which gives you a rather stark choice....do you want it too long, or do you want toe overlap?
Spa's 50 cm Audax bike has a 71 deg. head angle and 54mm offset steel fork, and its around 17mm shorter than it would be if I had stuck to 72 deg and 45mm. Now 17mm isn't a mile, but theres plenty of examples where going down a "size" makes less difference than that to the reach.

freeflow
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Re: Fit question stretched out on the hoods

Postby freeflow » 27 Aug 2014, 8:36am

I've been reading the above thread with some interest as I'm currently in the process of commissioning a custom frame. I've ended up with a 71 degree seat tube to ensure I can get the saddle in the right position and have scope for some adjustability. The headtube is 73 degrees and the virtual top tube is 610 mm. So big changes at the back but pretty similar to my current bike at the front.

Brucey
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Re: Fit question stretched out on the hoods

Postby Brucey » 27 Aug 2014, 9:09am

FWIW I agree with Colin's take on this.

The other choice for small people is get a custom built bike with (say) 650C wheels in it. Although the results can be superb, the costs are high and there is a limited choice/availability in tyres etc (mostly skinny ones, OK for unladen riding I guess). If you stuff a wheel on tour, you can be stuck.

I also note with interest that there are some (a few) OTP bikes that come with 26" wheels in the smaller sizes. I'm thinking of Decathlon's offerings here. I don't know how the geometry stacks up in these bikes overall (I'm expecting steep seat angles etc still) but these might be worth a look.

cheers
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531colin
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Re: Fit question stretched out on the hoods

Postby 531colin » 27 Aug 2014, 2:38pm

freeflow wrote:I've been reading the above thread with some interest as I'm currently in the process of commissioning a custom frame. I've ended up with a 71 degree seat tube to ensure I can get the saddle in the right position and have scope for some adjustability. The headtube is 73 degrees and the virtual top tube is 610 mm. So big changes at the back but pretty similar to my current bike at the front.


That's long. My 53cm roughstuff bike with 71 deg seat tube comes out at 600mm ETT....I'm 5' 10" and its my only bike that I have to fit with compact bars (ie short reach), the rest all have Nitto Noodles. If you are riding a similar beast with a 130mm stem, you should be OK. (I trawled through and found this....http://forum.ctc.org.uk/viewtopic.php?f=1&t=89656 )
Have you had a conversation with your builder about tall, heavy riders, steep head angles and shimmy?
(Lennard Zinn, I think, is the man.)

DeepdalePete
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Re: Fit question stretched out on the hoods

Postby DeepdalePete » 27 Aug 2014, 9:44pm

I haven't read every reply to this so excuse if this has been covered. Is that a lay back seat post on your bike? The saddle seems to be quite set back. I'd go at least an inch towards the front of the bike with that seat. If you take the line from the seat tube it should pass through the centre of the saddle but this looks set back far too much.

freeflow
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Re: Fit question stretched out on the hoods

Postby freeflow » 28 Aug 2014, 8:35am

That's long. My 53cm roughstuff bike with 71 deg seat tube comes out at 600mm ETT....I'm 5' 10" and its my only bike that I have to fit with compact bars (ie short reach), the rest all have Nitto Noodles.


How do you mean long. My current frame has a 578 mm virtual top tube and a 73 degree seat post angle. My new frame will have a 610 mm top tube and a 71 degree seat tube angle. At the moment I need a 130mm stem and the saddle (fizik arione) as far back as it will possibly go. Frame designer is well aware of my weight and is beefing up tube diameters appropriately. I currently use FSA compact bars.

The change in seat post angle is a small part of why I'm having a new frame built.

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531colin
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Re: Fit question stretched out on the hoods

Postby 531colin » 28 Aug 2014, 8:54am

That makes sense.
2 deg shallower seat tube angle means around 20mm more top tube behind the bottom bracket, so the actual reach of the new frame will only be about 10mm more than the old one.....everything else being equal you can come down to a 120mm stem.

freeflow
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Re: Fit question stretched out on the hoods

Postby freeflow » 28 Aug 2014, 9:23am

That makes sense.


Phew!! I though for one horrible moment I was going to have to make radical changes. The stem will be 120-130mm.

MikeF
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Re: Fit question stretched out on the hoods

Postby MikeF » 28 Aug 2014, 10:41am

531colin wrote:All the while the bike buying public prioritise fashion and form over function and comfort, then shorter people will be penalised by bikes that are too long.
Thanks to the fashion for using round-the-world load-luggers for a 10 mile potter through the lanes of Southern England, some people will now buy small tourers with 26" wheels, so its dead easy to fit a 5' tall person with a bike with drop bars, toe clearance and a short reach.
People get their "information" to make decisions about buying "light" bikes from internet fora, and ill-informed cycling journalists.
So you get a whole world of bikes with 700c wheels, 45mm offset carbon forks and head angle 72 deg or steeper, which gives you a rather stark choice....do you want it too long, or do you want toe overlap?
Spa's 50 cm Audax bike has a 71 deg. head angle and 54mm offset steel fork, and its around 17mm shorter than it would be if I had stuck to 72 deg and 45mm. Now 17mm isn't a mile, but theres plenty of examples where going down a "size" makes less difference than that to the reach.

I'm not sure if it's the buying public who are prioritising form and fashion, but rather the bike manufacturers and in particular their salesmen, who are pushing it. The Trek website seems to be one good example, but it's one of many. Also we now have model years for most bikes. :roll: - more sales pressure!

Well maybe I'm one of those who favour round-the-world load-luggers for "pottering about", but I like the ability to be not constricted to smooth :lol: surfaced roads and the ability to carry a certain amount. Therefore I have always tended to favour "touring" type bikes with rear racks and the practicality aspect of mudguards and lights. Maybe I'm wrong, but I don't cycle in groups or competitions.

I cannot find a 50cm Audax bike with steel forks on Spa's website, but it sounds interesting.
"It takes a genius to spot the obvious" - my old physics master

MikeF
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Re: Fit question stretched out on the hoods

Postby MikeF » 28 Aug 2014, 10:50am

Brucey wrote:FWIW I agree with Colin's take on this.

The other choice for small people is get a custom built bike with (say) 650C wheels in it. Although the results can be superb, the costs are high and there is a limited choice/availability in tyres etc (mostly skinny ones, OK for unladen riding I guess). If you stuff a wheel on tour, you can be stuck.

I also note with interest that there are some (a few) OTP bikes that come with 26" wheels in the smaller sizes. I'm thinking of Decathlon's offerings here. I don't know how the geometry stacks up in these bikes overall (I'm expecting steep seat angles etc still) but these might be worth a look.

cheers
It would be nice if there were more choice in wheel sizes and tyres, as that seems to be the main stumbling block for smaller size bikes, but I don't know how manufacturers can be persuaded to do that. 650c (584 is it?) would be a good choice and also 559 with a greater range of rims and tyres.
"It takes a genius to spot the obvious" - my old physics master

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531colin
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Re: Fit question stretched out on the hoods

Postby 531colin » 28 Aug 2014, 10:52am

50cm Ti Audax with steel forks is mentioned here http://www.spacycles.co.uk/products.php?plid=m1b0s21p2994 but its not on the dimensions table.
There should be a test bike in the shop, and I can dig out stuff like front centre and top tube length if you want.
As you are probably aware, the snag with small bikes is getting toe clearance without too long a reach, which is why the 50cm bike has a shallower head angle and longer offset forks than the rest.
Steel forks with low-rider mounts are available for the other Audax sizes as well, and that's probably hard to find on the website!

Mark1978
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Re: Fit question stretched out on the hoods

Postby Mark1978 » 28 Aug 2014, 11:27am

DeepdalePete wrote:I haven't read every reply to this so excuse if this has been covered. Is that a lay back seat post on your bike? The saddle seems to be quite set back. I'd go at least an inch towards the front of the bike with that seat. If you take the line from the seat tube it should pass through the centre of the saddle but this looks set back far too much.


Are you referring to me? The only pic I have on this thread post fit is the one on the previous page where I'm riding the bike and you can't see the saddle.

DeepdalePete
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Re: Fit question stretched out on the hoods

Postby DeepdalePete » 28 Aug 2014, 7:45pm

In the pic there's no one on the bike. This is the date of the photo: Sat Mar 16, 2013 6:35 pm