frame sizing query

[AP]

I've always assumed my bike was just about the right size for me. I bought
it from a guy who said 'you'll need to be six foot to ride this', which as
luck would have it I am. I've now been riding it happily for the best part
of a year, and certainly it feels ok to me. I now learn from Richard's
Bicycle Book that I should have at least 1 1/2" clearance between the top
tube and me family jewels, whereas in fact there's no gap at all. And
following up on that shock revelation, I learn from

http://www.prodigalchild.net/Bicycle6.htm#FrameChart

that I ought to be on a 58cm frame, whereas mine is 64cm. And that, it
strikes me, is quite a big difference. Is my frame too big for me, despite
feeling 'right'? Should I be thinking in terms of finding a 58cm machine?
Or should I just forget about the whole thing, given that I enjoy riding my
bike and it feels ok to me?

 

[Rob Morley]

In article <[email protected]>, AP
[email protected] says...
> I've always assumed my bike was just about the right size for me. I bought
> it from a guy who said 'you'll need to be six foot to ride this', which as
> luck would have it I am. I've now been riding it happily for the best part
> of a year, and certainly it feels ok to me. I now learn from Richard's
> Bicycle Book that I should have at least 1 1/2" clearance between the top
> tube and me family jewels, whereas in fact there's no gap at all. And
> following up on that shock revelation, I learn from
>
> http://www.prodigalchild.net/Bicycle6.htm#FrameChart
>
> that I ought to be on a 58cm frame, whereas mine is 64cm. And that, it
> strikes me, is quite a big difference. Is my frame too big for me, despite
> feeling 'right'? Should I be thinking in terms of finding a 58cm machine?
> Or should I just forget about the whole thing, given that I enjoy riding my
> bike and it feels ok to me?
>
If you can comfortably straddle the frame with your feet flat on the
ground then it's not hugely too big for you. If you haven't noticed a
problem in nearly a year then don't worry about it too much. If you buy
another bike I'd suggest going for something a bit smaller - 22.5" -
23.5" is probably about right for a touring bike, but be aware that the
length of the top tube is probably more important than the height of the
seat tube, and the bottom bracket height also plays a part. Mountain
bikes should generally be at least 3" smaller.

 

[Paul Boyd]

AP said the following on 10/01/2007 12:01:

> Or should I just forget about the whole thing, given that I enjoy riding my
> bike and it feels ok to me?

I'm assuming this is a road bike, based on the frame size. The ultimate
question is - when did you last worry about smacking your family jewels
on the top tube?

I would go with "if it feels right, it is right". FWIW, my road bike is
about the same size, I'm also 6ft, and I've had it for nearly 10 years
without even thinking about top tube clearance. I will, of course, now
have to check at home-time tonight!

--
Paul Boyd
http://www.paul-boyd.co.uk/

 

[AP]

You do that Paul. And while you're at it, check to make sure the distance
between extended pedal and top of saddle = your inside leg x 1.09.
(Richard's BB again). Mine isn't!
"Paul Boyd" <usenet.dont.work@plusnet> wrote in message
news:[email protected]...
> AP said the following on 10/01/2007 12:01:
>
>> Or should I just forget about the whole thing, given that I enjoy riding
>> my bike and it feels ok to me?
>
> I'm assuming this is a road bike, based on the frame size. The ultimate
> question is - when did you last worry about smacking your family jewels on
> the top tube?
>
> I would go with "if it feels right, it is right". FWIW, my road bike is
> about the same size, I'm also 6ft, and I've had it for nearly 10 years
> without even thinking about top tube clearance. I will, of course, now
> have to check at home-time tonight!
>
> --
> Paul Boyd
> http://www.paul-boyd.co.uk/

 

[POHB]

AP wrote:
> I should have at least 1 1/2" clearance between the top
> tube and me family jewels, whereas in fact there's no gap at all.

Does that take into account variations due to temperature?

 

[Bronzie]

On Jan 10, 12:01 pm, "AP" <[email protected]> wrote:
> ..... I ought to be on a 58cm frame, whereas mine is 64cm.

I ride a mixture of 56 and 58cm frames and I'm 6'2". I find that the
reach (ie the top tube length and stem combination) is more important
than the standover height for a road frame, although for the sake of
your vital organs, there should be come clearance between the top tube
and your crotch.

But like you say, if you've found a comfortable position, why worry
(although I can't help but think that you are probably too stretched
out on the bike - might give rise to back problems long term?).

Cheers
Bronzie

 

[Rob Morley]

In article <[email protected]>,
Bronzie
[email protected] says...
> On Jan 10, 12:01 pm, "AP" <[email protected]> wrote:
> > ..... I ought to be on a 58cm frame, whereas mine is 64cm.
>
> I ride a mixture of 56 and 58cm frames and I'm 6'2". I find that the
> reach (ie the top tube length and stem combination) is more important
> than the standover height for a road frame, although for the sake of
> your vital organs, there should be come clearance between the top tube
> and your crotch.
>
> But like you say, if you've found a comfortable position, why worry
> (although I can't help but think that you are probably too stretched
> out on the bike - might give rise to back problems long term?).
>
That depends on whether the frame has a modern geometry - lots of older
(or cheaper) frames were built with the top tube pretty much the same
length regardless of seat tube length.

 

[Rob Morley]

In article <[email protected]>, AP
[email protected] says...
> You do that Paul. And while you're at it, check to make sure the distance
> between extended pedal and top of saddle = your inside leg x 1.09.
> (Richard's BB again). Mine isn't!

It's a bit of an old-fashioned idea, but it's not a bad starting point.
These days people tend to sit a bit lower and further back, except for
triathletes who sit higher and further forward, but starting with 1.09
helps the uninitiated get it in the right field. The other rules of
thumb, like determining stem length by putting your elbow on the nose of
the saddle and seeing where your fingertips are, or seeing if the bars
obscure the front hub, are somewhat less reliable.

 

[Pete Biggs]

AP wrote:
> I've always assumed my bike was just about the right size for me. I
> bought it from a guy who said 'you'll need to be six foot to ride
> this', which as luck would have it I am. I've now been riding it
> happily for the best part of a year, and certainly it feels ok to me.
> I now learn from Richard's Bicycle Book that I should have at least 1
> 1/2" clearance between the top tube and me family jewels, whereas in
> fact there's no gap at all. And following up on that shock
> revelation, I learn from
> http://www.prodigalchild.net/Bicycle6.htm#FrameChart
>
> that I ought to be on a 58cm frame, whereas mine is 64cm. And that, it
> strikes me, is quite a big difference. Is my frame too big for me,
> despite feeling 'right'? Should I be thinking in terms of finding a
> 58cm machine? Or should I just forget about the whole thing, given
> that I enjoy riding my bike and it feels ok to me?

Nevermind all this "should" and "ought" business. If you're comfortable and
can control the bike ok, that's all that matters.

Even when there is plenty of top tube cleararance /normally/, it's still
possible to squash the two veg if you come off the pedals as well as the
saddle in some weird incident.

~PB

 

[Simon Brooke]

in message <[email protected]>, AP
('[email protected]') wrote:

> I've always assumed my bike was just about the right size for me. I
> bought
> it from a guy who said 'you'll need to be six foot to ride this', which
> as luck would have it I am. I've now been riding it happily for the best
> part of a year, and certainly it feels ok to me. I now learn from
> Richard's Bicycle Book that I should have at least 1 1/2" clearance
> between the top tube and me family jewels, whereas in fact there's no gap
> at all. And following up on that shock revelation, I learn from
>
> http://www.prodigalchild.net/Bicycle6.htm#FrameChart
>
> that I ought to be on a 58cm frame, whereas mine is 64cm. And that, it
> strikes me, is quite a big difference. Is my frame too big for me,
> despite
> feeling 'right'? Should I be thinking in terms of finding a 58cm
> machine? Or should I just forget about the whole thing, given that I
> enjoy riding my bike and it feels ok to me?

Frame geometry has changed a lot in the past fifteen years. Twenty-five
years ago I used to ride roadbikes with 26.5" frames - that's about 67cm.
Now I ride road bikes with 60cm frames. What's changed? Seatposts have got
stiffer and lighter, and as seatposts have got stiffer and lighter so it's
made sense to expose more seatpost. It also allows you to get your bars
below the level of your saddle, which most roadies like these days.
Stiffer frame materials have also contributed to this revolution.

So a modern road frame for someone of 6' 2", like me, is about 60cm,
with 'compact geometry' (sloping top tube) frames being even smaller.

What matters is the triangle between bottom bracket, saddle, and
handlebars. If you can achieve the same dimensions for the three sides of
that triangle, the bike will fit.

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/
Copyright (c) Simon Brooke; All rights reserved. Permission is
granted to transfer this message via UUCP or NNTP and to store it
for the purpose of archiving or further transfer. Permission is
explicitly denied to use this message as part of a 'Web Forum', or
to transfer it by HTTP.

 

[Paul Boyd]

On 10/01/2007 13:08, AP said,
> You do that Paul. And while you're at it, check to make sure the distance
> between extended pedal and top of saddle = your inside leg x 1.09.
> (Richard's BB again). Mine isn't!

I did, and the clearance between nadgers and top tube is roughly zero.
With my feet flat on the floor, I can drop maybe an inch before bone
hits metal.

As for the 1.09 thingy, mine isn't either - more like 1.05. Dunno if
that's supposed to be good or bad, but it's been like it for 10 years!

--
Paul Boyd
http://www.paul-boyd.co.uk/

 

[Paul Boyd]

On 10/01/2007 14:50, Rob Morley said,

> thumb, like determining stem length by putting your elbow on the nose of
> the saddle and seeing where your fingertips are, or seeing if the bars
> obscure the front hub, are somewhat less reliable.

I've never had that one work - it's just too short.

--
Paul Boyd
http://www.paul-boyd.co.uk/

 

[AP]

Hmmmm...yes....but then again...

I do buy the essential 'it ain't broke, so...' philosophy. And I do love
riding my current bike. And I do know that constantly striving for better is
a road to madness, strewn with broken spirits and titanium pedals at
£139.99. And yet...

Perhaps it's actually *because* I love riding my current bike so much.
Because I appreciate how much better it is than predecessors, and I'm
wondering how much further there might actually be to go, at pretty modest
cost. I keep reading how frame size is crucial, and I guess I'm just
thinking maybe going to just the right size would give me an additional
boost to equal the one I got in going from my last bike - a Raleigh
Dynatech, itself no clunker - to my Benotto. (And I was totally comfortable
and in control of that - as I was with my previous Carlton Criterium, which
I still remember with fondness, and which a friend now rides.) There've been
a couple of real beauties on ebay recently that have gone for around the
ton. That's doable. Is it worth thinking about? That's all.

Alan
"Pete Biggs" <[email protected]> wrote in
message news:[email protected]...
> AP wrote:
> > I've always assumed my bike was just about the right size for me. I
> > bought it from a guy who said 'you'll need to be six foot to ride
> > this', which as luck would have it I am. I've now been riding it
> > happily for the best part of a year, and certainly it feels ok to me.
> > I now learn from Richard's Bicycle Book that I should have at least 1
> > 1/2" clearance between the top tube and me family jewels, whereas in
> > fact there's no gap at all. And following up on that shock
> > revelation, I learn from
> > http://www.prodigalchild.net/Bicycle6.htm#FrameChart
> >
> > that I ought to be on a 58cm frame, whereas mine is 64cm. And that, it
> > strikes me, is quite a big difference. Is my frame too big for me,
> > despite feeling 'right'? Should I be thinking in terms of finding a
> > 58cm machine? Or should I just forget about the whole thing, given
> > that I enjoy riding my bike and it feels ok to me?
>
> Nevermind all this "should" and "ought" business. If you're comfortable
and
> can control the bike ok, that's all that matters.
>
> Even when there is plenty of top tube cleararance /normally/, it's still
> possible to squash the two veg if you come off the pedals as well as the
> saddle in some weird incident.
>
> ~PB
>
>

 

[AP]

Sorry if I'm being thick, but I don't understand your crucial

What matters is the triangle between bottom bracket, saddle, and
> handlebars. If you can achieve the same dimensions for the three sides of
> that triangle, the bike will fit.

Doesn't that mean an equilateral triangle? I know it can't, but I'm baffled
as to the 'dimensions' you refer to.

Re the bit I *do* understand, it's an old bike. 20 years would be my guess.
And totally 'conventional' in shape. And it's 64cm, which according to the
chart I saw makes it 2" more than 'ideal'. I'm heartened to hear of your
67cm frame. That makes 64cm for me, at 6 feet, sound less outlandish. And it
does feel fine, which I guess is really some kind of criterion...

"Simon Brooke" <[email protected]> wrote in message
news:[email protected]...
> in message <[email protected]>, AP
> ('[email protected]') wrote:
>
> > I've always assumed my bike was just about the right size for me. I
> > bought
> > it from a guy who said 'you'll need to be six foot to ride this', which
> > as luck would have it I am. I've now been riding it happily for the best
> > part of a year, and certainly it feels ok to me. I now learn from
> > Richard's Bicycle Book that I should have at least 1 1/2" clearance
> > between the top tube and me family jewels, whereas in fact there's no
gap
> > at all. And following up on that shock revelation, I learn from
> >
> > http://www.prodigalchild.net/Bicycle6.htm#FrameChart
> >
> > that I ought to be on a 58cm frame, whereas mine is 64cm. And that, it
> > strikes me, is quite a big difference. Is my frame too big for me,
> > despite
> > feeling 'right'? Should I be thinking in terms of finding a 58cm
> > machine? Or should I just forget about the whole thing, given that I
> > enjoy riding my bike and it feels ok to me?
>
> Frame geometry has changed a lot in the past fifteen years. Twenty-five
> years ago I used to ride roadbikes with 26.5" frames - that's about 67cm.
> Now I ride road bikes with 60cm frames. What's changed? Seatposts have got
> stiffer and lighter, and as seatposts have got stiffer and lighter so it's
> made sense to expose more seatpost. It also allows you to get your bars
> below the level of your saddle, which most roadies like these days.
> Stiffer frame materials have also contributed to this revolution.
>
> So a modern road frame for someone of 6' 2", like me, is about 60cm,
> with 'compact geometry' (sloping top tube) frames being even smaller.
>
> What matters is the triangle between bottom bracket, saddle, and
> handlebars. If you can achieve the same dimensions for the three sides of
> that triangle, the bike will fit.
>
> --
> [email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/
> Copyright (c) Simon Brooke; All rights reserved. Permission is
> granted to transfer this message via UUCP or NNTP and to store it
> for the purpose of archiving or further transfer. Permission is
> explicitly denied to use this message as part of a 'Web Forum', or
> to transfer it by HTTP.
>

 

[Pete Biggs]

AP wrote:
> Hmmmm...yes....but then again...
>
> I do buy the essential 'it ain't broke, so...' philosophy. And I do
> love riding my current bike. And I do know that constantly striving
> for better is a road to madness, strewn with broken spirits and
> titanium pedals at £139.99. And yet...
>
> Perhaps it's actually *because* I love riding my current bike so much.
> Because I appreciate how much better it is than predecessors, and I'm
> wondering how much further there might actually be to go, at pretty
> modest cost. I keep reading how frame size is crucial, and I guess
> I'm just thinking maybe going to just the right size would give me an
> additional boost to equal the one I got in going from my last bike -
> a Raleigh Dynatech, itself no clunker - to my Benotto. (And I was
> totally comfortable and in control of that - as I was with my
> previous Carlton Criterium, which I still remember with fondness, and
> which a friend now rides.) There've been a couple of real beauties on
> ebay recently that have gone for around the ton. That's doable. Is it
> worth thinking about? That's all.

You happen might find a smaller bike faster and more exciting. How much of
that will be down to the frame size & shape, and how much will be due to any
other differences, including any unintentional small differences with the
riding position.... Well, it's going to be hard to know. I think it's well
worth a go (and I happen to prefer my smaller bikes to my largest bike), but
make sure some other things on the bike are superior as well to increase
chance of satisfaction.

As far as comfort goes, though, you can't get better than "totally
comfortable". I'm quite convinced there's no such actual thing as comfort,
only discomfort. So if you feel no discomfort at all, you can't be any more
comfortable. No one can be more comfortable than a dead person!

~PB

 

[Rob Morley]

In article <[email protected]>, AP
[email protected]NVALID says...
> Sorry if I'm being thick, but I don't understand your crucial
>
> What matters is the triangle between bottom bracket, saddle, and
> > handlebars. If you can achieve the same dimensions for the three sides of
> > that triangle, the bike will fit.
>
> Doesn't that mean an equilateral triangle? I know it can't, but I'm baffled
> as to the 'dimensions' you refer to.

The relative positions of the three bike/body interface points - you can
have a small frame with a long seatpost and stem, or a large frame with
a short seatpost and stem, and achieve exactly the same riding position
on each. That's not to say that both bikes will ride the same, because
their balance may be quite different, but both will fit.
>
> Re the bit I *do* understand, it's an old bike. 20 years would be my guess.
> And totally 'conventional' in shape. And it's 64cm, which according to the
> chart I saw makes it 2" more than 'ideal'. I'm heartened to hear of your
> 67cm frame. That makes 64cm for me, at 6 feet, sound less outlandish. And it
> does feel fine, which I guess is really some kind of criterion...
>
I've a feeling that my Holdsworth tourer turned out to be a 25.25" - I
think I ordered a 24" and didn't notice the discrepancy for years, the
top tube length was the same for both sizes. My current road bike is a
23". The size of the Holdsworth was never a problem, and I sometimes
used to ride it quite hard off-road.

 

[Simon Brooke]

in message <[email protected]>, AP
('[email protected]') wrote:

> Sorry if I'm being thick, but I don't understand your crucial
>
> What matters is the triangle between bottom bracket, saddle, and
>> handlebars. If you can achieve the same dimensions for the three sides
>> of that triangle, the bike will fit.
>
> Doesn't that mean an equilateral triangle? I know it can't, but I'm
> baffled as to the 'dimensions' you refer to.

OK. Suppose you have a frame with a seat tube that's 64cm long, and you
expose 6cm of seatpost. Then you switch to a frame with a seat tube that's
60cm long, but now you expose 10cm of seatpost. The total distance between
the bottom bracket axle and the saddle hasn't changed, although the frame
is smaller. That distance is, for comfort and efficiency, determined by
the length of your legs (which are not necessarily the same length as
those of someone else who happens to be the same height as you).

Now consider the distance from the saddle to the handlebars. The ideal
distance is a function of the length of your back and your arms, and at
what angle you find it comfortable to relax your shoulders. Your new,
smaller frame may have a shorter top tube (although it may not - modern
frames have relatively longer top tubes than older ones). If so, you make
up the difference in distance by using a longer stem. The actual distance
from the saddle to the bars - if your old bike fitted well - should remain
the same.

Finally the distance from the bottom bracket axle to the bars. Again, this
is a function of your body - in this case, how much it's comfortable for
you to bend your back. So you should keep it the same on the new bike as
on the old - assuming the old bike was a good fit. To keep the distance
the same, adjust the angle of your new stem and the number of headset
stackers you use.

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/

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