Is it possible to shorten a bicycle frame?

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reohn2
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Re: Is it possible to shorten a bicycle frame?

Postby reohn2 » 12 Mar 2018, 11:29am

Gattonero wrote:
horizon wrote:
Gattonero wrote:
My take is, and I know this hurts, if one needs specific measurements then the frame has to follow. I.e. a "shorter" frame may imply a lower flexibility of the body, so one has to think how much a good health is worth. Is not just about using the shortest and tallest stem one can find.


Gattonero: can you say a bit more as I'm not sure I follow. What should one do/not do?


There seems to be a general belief that "the higher the bars, the more comfortable the bike it is", and this implies the belief that "a comfortable bicycle" would resolve the body problems.
My opinion is to sort out the problems in the first place, and not masking them with a cycling position that won't show where the problem is. Of course, there are people who have some serious issues, and this requires even more attention; but judging how many people do ride road bikes with very short stems and high bars, I cannot help in thinking if back/posture problems are such a widespread problem even within active people? Or more likely, the bike does not fit the rider?

IMO the problem lies with racing and the racing crouch being sold as the normal riding position(I don't think that's the case with Horizon),it isn't and never has been for the vast majority of cyclists.
Bikes are now being sold to people with Wiggo or Froome-itis that's where the problem lies IMO,ordinary people being sold bikes designed for althetes to people with little chance of reaching that potential.
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Gattonero
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Re: Is it possible to shorten a bicycle frame?

Postby Gattonero » 15 Mar 2018, 2:10pm

reohn2 wrote:
Gattonero wrote:
horizon wrote:
Gattonero: can you say a bit more as I'm not sure I follow. What should one do/not do?


There seems to be a general belief that "the higher the bars, the more comfortable the bike it is", and this implies the belief that "a comfortable bicycle" would resolve the body problems.
My opinion is to sort out the problems in the first place, and not masking them with a cycling position that won't show where the problem is. Of course, there are people who have some serious issues, and this requires even more attention; but judging how many people do ride road bikes with very short stems and high bars, I cannot help in thinking if back/posture problems are such a widespread problem even within active people? Or more likely, the bike does not fit the rider?

IMO the problem lies with racing and the racing crouch being sold as the normal riding position(I don't think that's the case with Horizon),it isn't and never has been for the vast majority of cyclists.
Bikes are now being sold to people with Wiggo or Froome-itis that's where the problem lies IMO,ordinary people being sold bikes designed for althetes to people with little chance of reaching that potential.


I think that a "normal" person shouldn't have too much of trouble to lace up the shoes by bending the torso down. Hence, a certain degreee of flexibility should be the norm and not the exception.

Having said that, I'm with you in regards of most road bikes, been sold to the wrong user. A road bike is a road bike, got to bend your back otherwise becomes a different bike. Again, when people needs their bars higher and closer they''re on the wrong bike, no doubt.
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reohn2
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Re: Is it possible to shorten a bicycle frame?

Postby reohn2 » 15 Mar 2018, 2:51pm

Gattonero wrote:..?..... when people need their bars higher and closer they''re on the wrong bike, no doubt.

And have the wrong vision of themselves as cyclists
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Re: Is it possible to shorten a bicycle frame?

Postby Gattonero » 16 Mar 2018, 8:28am

reohn2 wrote:
Gattonero wrote:..?..... when people need their bars higher and closer they''re on the wrong bike, no doubt.

And have the wrong vision of themselves as cyclists


I meant, for "road" or "sportive" bikes, leisure bikes is a different thing and I would say this applies to a less extent?
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since you have to sweat up the hills and coast down them.
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Re: Is it possible to shorten a bicycle frame?

Postby Vorpal » 16 Mar 2018, 8:32am

reohn2 wrote:
Gattonero wrote:..?..... when people need their bars higher and closer they''re on the wrong bike, no doubt.

And have the wrong vision of themselves as cyclists

Or we can jst think of it as everyone is different and likes different things in their bikes?
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Re: Is it possible to shorten a bicycle frame?

Postby Gattonero » 16 Mar 2018, 8:45am

Vorpal wrote:
reohn2 wrote:
Gattonero wrote:..?..... when people need their bars higher and closer they''re on the wrong bike, no doubt.

And have the wrong vision of themselves as cyclists

Or we can jst think of it as everyone is different and likes different things in their bikes?


Yes but a road bike is a road bike with a few common things.
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Re: Is it possible to shorten a bicycle frame?

Postby reohn2 » 16 Mar 2018, 8:48am

Gattonero wrote:
reohn2 wrote:
Gattonero wrote:..?..... when people need their bars higher and closer they''re on the wrong bike, no doubt.

And have the wrong vision of themselves as cyclists


I meant, for "road" or "sportive" bikes, leisure bikes is a different thing and I would say this applies to a less extent?

That depends, see a lot of cyclists in team type kit,road and sportive type bikes who'll rarely if ever reach the drops and some who look very uncomfortable on the tops and hoods.
These people have been sold the wrong bike because the road and sportive type bike is based on a race bike with saddle to handlebar height difference of 10cm or greater,OK if you're fit flexible and slim,the majority aren't and there's not much choice,they're being sold wiggo froome-itis that doesn't fit the average joe and joess.
The bike looks the part the average human doesn't easily fold up to fit it,what's worse I see the same problem with touring bikes too,short headtubes lots of spacers under the stem to make the bike fit,headtubes are too short for the comfort of the masses.
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horizon
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Re: Is it possible to shorten a bicycle frame?

Postby horizon » 16 Mar 2018, 9:45am

Can I just ask for an opinion on this (I'm separating leg length from torso position for a moment):

I'm happy and wish to flex forward at times. However is this different from arm position? I don't think anyone thinks it a good idea to round the back and shoulders inwards and stretch the arms out to reach the bars. But what if the hand position stayed exactly the same and the back used the arms as cantilevers to move up and down? Where you put your hands/elbows would therefore would be where you put your hands/elbows - the back changes its horizontal position as required but not in order to get the hands onto the bars - the hands will be supporting the back/torso from where that support is most comfortable (and probably not from a stretched out position - imagine doing a press-up).

My point is that the bars need to be wherever they need to be (in relation to the arms/elbows/hands) regardless of upper body flex and that that position is upset once the saddle goes too far back.
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Re: Is it possible to shorten a bicycle frame?

Postby Vorpal » 16 Mar 2018, 10:33am

I don't think that your arms should support your back. Your back should support your back.

Beyond that, I think it depends somewhat on the purpose of your set-up and personal comfort.

There is some difference between
colin_bike_position.jpg
(I hope it's okay that I borrow Colin's picture!)

and
peleton-riding-by-sunflowers.jpg
from http://ayay.co.uk/backgrounds/sports/cy ... lowers.jpg

But the arm positions are not hugely different.

The saddle position has to be determined first, based upon the relationship with the bottom bracket & pedals, the purpose of the set-up, etc. There are a range of positions that follow an arc around the BB that can be used; if you remember one of the threads from a few years ago about bike positioning viewtopic.php?f=5&t=74985&hilit=bike+position+help&start=60#p666914

Yes, too far back or too far forward will upset this relationship, but I think that would mean either, you are outside the 'arc', or outside of what fits your body.
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Brucey
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Re: Is it possible to shorten a bicycle frame?

Postby Brucey » 16 Mar 2018, 10:45am

horizon wrote:.... I don't think anyone thinks it a good idea to round the back and shoulders inwards and stretch the arms out to reach the bars....


I think that it doesn't matter that much provided you get the rest of your position right.

If you get the saddle in the right place and (as Vorpal says) you get your back supporting your back, it matters relatively little where your hands and arms end up; in extremis you can end up with a superman-type position.

In any case your hands can end up supporting the weight of your arms only, eg with just your fingers crooked over the top of the handlebars, with no muscle tension to speak of in your entire upper body, other than in your neck perhaps, to keep your head upright.

You can test very easily whether your position is right (for touring/comfort); when you are just tapping along, you should be able to just rest your fingertips on the handlebar, without applying much pressure, without changing the stress in your back etc, and without feeling uncomfortable.

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horizon
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Re: Is it possible to shorten a bicycle frame?

Postby horizon » 16 Mar 2018, 10:48am

Vorpal wrote:I don't think that your arms should support your back. Your back should support your back.

Beyond that, I think it depends somewhat on the purpose of your set-up and personal comfort.



Vorpal, thank you for that.

I too hesitated when I wrote support the back as I know that isn't the idea. But the hands have to go somewhere and usefully assist in balancing the bike and rider and steering the bike.

What I don't like is the arms stretching forward to reach the bars (which obviously they have to do) and then pulling the shoulders forward. What I cannot work out is whether a more horizontal back position actually helps this as the back is moving in an arc.
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horizon
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Re: Is it possible to shorten a bicycle frame?

Postby horizon » 18 Mar 2018, 6:41pm

Brucey wrote:
horizon wrote:.... I don't think anyone thinks it a good idea to round the back and shoulders inwards and stretch the arms out to reach the bars....


I think that it doesn't matter that much provided you get the rest of your position right.



Just a quick update on this. This bike is for sale at present (I hope the OP doesn't mind my using the photo :) ):

viewtopic.php?f=40&t=120726

It's a good bike and I wouldn't mind buying it but it's exactly the same as one I used to have. It's a 57 cm size. I sold mine and bought a 59 cm. But AFAIK the reach is greater on the 57 than on the 59. I'm completely baffled by this. I would just add that the 57 has a 74 deg angle seat tube. It would seem that you are right - this particular dimension (reach) is of no importance at all.

Dawes Super Galaxy reduced.jpg
Dawes Super Galaxy reduced.jpg (70.08 KiB) Viewed 524 times
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531colin
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Re: Is it possible to shorten a bicycle frame?

Postby 531colin » 19 Mar 2018, 9:40am

Can you post/link the geometry of those Dawes?
To measure "reach" (frame reach) drop a plumbline through the bottom bracket axle; reach is the horizontal distance from that line to the top of the head tube. It is independent of seat tube angle. Assuming the rider sets their saddle position fore and aft with reference to the bottom bracket, then reach tells you if you can get the bars at the right reach from the saddle

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horizon
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Re: Is it possible to shorten a bicycle frame?

Postby horizon » 19 Mar 2018, 10:32am

Bike for sale: 1994 57 cm Dawes Super Galaxy
My original bike: 1997 57 cm Dawes Super Galaxy
My current bike: 2000 59 cm Dawes Horizon
Geometry Information obtained from 1999 Dawes brochure.

Table covers Galaxy, Super Galaxy and Horizon so it's a reasonable assumption that they share the same frame (Reynolds 531) and this frame was the same over this time period. But in any case the comparison is taken from the same table. All have horizontal top tubes from which I assume the effective top tube to be the same. If I have time I will scan the table.

As regards reach, the table gives reach as from seat post to bar clamp which to me is irrelevant as the seat angle changes. So I use a rule of thumb that says the real measurement that I need equals effective top tube (in this case, as I said above, the TT is horizontal so equals ETT) plus or minus 10 mm per degree of seat tube angle from a 73 deg starting point.

57 cm size: (effective) top tube 567 mm Seat angle 74 deg = real length 577 mm
59 cm size: (effective) top tube 573 mm Seat angle 73 deg 30' = real length 576 mm

Goodness knows if I have undertood it all correctly or if my maths is right but that is how it appears to me. I don't find the same with other bikes although the same pattern occurs that there is usually a disproportionately small change in "real" top tube compared to seat tube. The figures in the brochure could of course be wrong but they match my own Horizon and we could always ask the vendor of the 57 to run some checks! My general impression on bike sizing is that leg length is everything, saddle set back is ignored and reach is left to take care of itself.
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Re: Is it possible to shorten a bicycle frame?

Postby Bmblbzzz » 19 Mar 2018, 12:38pm

Vorpal wrote:I don't think that your arms should support your back. Your back should support your back.

Beyond that, I think it depends somewhat on the purpose of your set-up and personal comfort.

There is some difference between colin_bike_position.jpg (I hope it's okay that I borrow Colin's picture!)

and
peleton-riding-by-sunflowers.jpg from http://ayay.co.uk/backgrounds/sports/cy ... lowers.jpg

But the arm positions are not hugely different.

The saddle position has to be determined first, based upon the relationship with the bottom bracket & pedals, the purpose of the set-up, etc. There are a range of positions that follow an arc around the BB that can be used; if you remember one of the threads from a few years ago about bike positioning viewtopic.php?f=5&t=74985&hilit=bike+position+help&start=60#p666914

Yes, too far back or too far forward will upset this relationship, but I think that would mean either, you are outside the 'arc', or outside of what fits your body.

Looking at the arm position, Colin's arms actually look more stretched out than the pros'. They both have a similar angle between upper arm and shoulder but his are straight whereas theirs have a distinct bend at the elbow, and the distance by which the hands are forward of the shoulders looks about equal.