Road bike fit

I'm shopping for a new road
bike, with better components than the twenty-year-old 105 components
on my Trek 2100. The main bikes in the price range I'm aiming for
include a Trek Madone, Cannondale Synapse or Supersix, or Cervelo
(like an R3). I'm having trouble with finding a bike that fits.
Cannondale and Cervelo both seem to have frame sizes of 51 and 54 but
nothing in-between. My current road bike is 52cm and that feels
right. I've tried both the 51' with the seat raised and the 54' with
the seat lowered. The person at the bike store who worked with me
didn't really seem able to say, "You can tell if it's the right frame
size if..." The 54' is too tall, even with the seat lowered, while
the 51' feels a bit too cramped. I know that comfort (since I'm not
trying to race any more) is important but there are multiple
adjustments that could be made, like stem height, to make the right
sized frame feel more comfortable. Is there any good technique
beyond
standing over the top tube and assessing how much space there is
between the bike and the rider to determine if I'm choosing the right
frame size? There are probably bike shops where I could get more help
with this but I haven't found any yet in my area (Pasadena to Pomona
in LA county, southern California). Any suggestions? Thanks.

Ken

On Dec 18, 6:25*am, OccasionalFlyer wrote:
I'm shopping for a new road
bike, with better components than the twenty-year-old 105 components
on my Trek 2100. *The main bikes in the price range I'm aiming for
include a Trek Madone, Cannondale Synapse or Supersix, or Cervelo
(like an R3). *I'm having trouble with finding a bike that fits.
Cannondale and Cervelo both seem to have frame sizes of 51 and 54 but
nothing in-between. My current road bike is 52cm and that feels
right. *I've tried both the 51' with the seat raised and the 54' with
the seat lowered. *The person at the bike store who worked with me
didn't really seem able to say, "You can tell if it's the right frame
size if..." *The 54' is too tall, even with the seat lowered, while
the 51' feels a bit too cramped. *I know that comfort (since I'm not
trying to race any more) is important but there are multiple
adjustments that could be made, like stem height, to make the right
sized frame feel more comfortable. *Is there any good technique
beyond
standing over the top tube and assessing how much space there is
between the bike and the rider to determine if I'm choosing the right
frame size? *There are probably bike shops where I could get more help
with this but I haven't found any yet in my area (Pasadena to Pomona
in LA county, southern California). *Any suggestions? Thanks.

Ken

For an easier fit, keep your crank length short. This allows more
movement of your saddle and less strain in your legs and back. The
less you wish to strain yourself, the shorter the cranks should be.
I like to think that crank length should be no more than 1/2 the femur
length and no more than 1/5 of inside-leg length. The use of shorter
cranks could make both frames suitable. Also check the bar width,
before thinking of modifying its position with a change of stem. Too
many people accept what's stock when stock is simply the wrong size.
If the parts can't be adjusted to fit you, they need changing and you
should push for that as it's your money. The saddle should also be
positioned so that the saddle rails are clamped centrally. If
adjustment shifts the saddle to the end of the rails, you need a
different seat pin or a frame with a different seat tube angle.

It's nearly always better to modify what you have which is already so
close to perfect.
Subtleties in saddle shape can also affect how one perceives the
general fit of the bike is. Use the saddle you are familiar with.

"OccasionalFlyer" wrote in message ...

[snip]

Is there any good technique beyond
standing over the top tube and assessing how much space there is
between the bike and the rider to determine if I'm choosing the right
frame size?

As you say you have an old bike that is comfortable then what I would do is take these three key measurements from it:

1. Bar width.

2. Distance from centre of bottom bracket to top of saddle measured along the seat tube.

3. Distance from back of saddle to brake hoods ignoring any cut out at the back of the saddle.

You can obviously match 1. by using the same width bar. If you can achieve 2 and 3 by one or a combination of moving the saddle back or forward within 1 cm of being centred on the rails and selecting a stem between 90 and 120 cms you should be able to get very close to the ride comfort of your existing bike without compromising pedalling efficiency or bike stability.

Finally make sure you insist on a test ride.

Graham.

"Graham" wrote in message ...

"OccasionalFlyer" wrote in message ...

[snip]

Is there any good technique beyond
standing over the top tube and assessing how much space there is
between the bike and the rider to determine if I'm choosing the right
frame size?

As you say you have an old bike that is comfortable then what I would do is take these three key measurements from it:

1. Bar width.

2. Distance from centre of bottom bracket to top of saddle measured along the seat tube.

3. Distance from back of saddle to brake hoods ignoring any cut out at the back of the saddle.

You can obviously match 1. by using the same width bar. If you can achieve 2 and 3 by one or a combination of moving the saddle back or forward within 1 cm of being centred on the rails and selecting a stem between 90 and 120 cms you should be able to get very close to the ride comfort of your existing bike without compromising pedalling efficiency or bike stability.

Finally make sure you insist on a test ride.

Graham.

Should have added a 4. being vertical drop from top of saddle to top of bars. This can be maintained by choosing a stem with the appropriate rise.

Graham.

On 12/18/2011 1:25 AM, OccasionalFlyer wrote:
I'm shopping for a new road
bike, with better components than the twenty-year-old 105 components
on my Trek 2100. The main bikes in the price range I'm aiming for
include a Trek Madone, Cannondale Synapse or Supersix, or Cervelo
(like an R3). I'm having trouble with finding a bike that fits.
Cannondale and Cervelo both seem to have frame sizes of 51 and 54 but
nothing in-between. My current road bike is 52cm and that feels
right. I've tried both the 51' with the seat raised and the 54' with
the seat lowered. The person at the bike store who worked with me
didn't really seem able to say, "You can tell if it's the right frame
size if..." The 54' is too tall, even with the seat lowered, while
the 51' feels a bit too cramped. I know that comfort (since I'm not
trying to race any more) is important but there are multiple
adjustments that could be made, like stem height, to make the right
sized frame feel more comfortable. Is there any good technique
beyond
standing over the top tube and assessing how much space there is
between the bike and the rider to determine if I'm choosing the right
frame size? There are probably bike shops where I could get more help
with this but I haven't found any yet in my area (Pasadena to Pomona
in LA county, southern California). Any suggestions? Thanks.

Ken




Specialized Tarmac comes in 49, 52 and 54. Probably similar to the Trek
or Cervelo that you are considering. May be worth a look.

On Dec 17, 11:25*pm, OccasionalFlyer wrote:
I'm shopping for a new road
bike, with better components than the twenty-year-old 105 components
on my Trek 2100. *The main bikes in the price range I'm aiming for
include a Trek Madone, Cannondale Synapse or Supersix, or Cervelo
(like an R3). *I'm having trouble with finding a bike that fits.
Cannondale and Cervelo both seem to have frame sizes of 51 and 54 but
nothing in-between. My current road bike is 52cm and that feels
right. *I've tried both the 51' with the seat raised and the 54' with
the seat lowered. *The person at the bike store who worked with me
didn't really seem able to say, "You can tell if it's the right frame
size if..." *The 54' is too tall, even with the seat lowered, while
the 51' feels a bit too cramped. *I know that comfort (since I'm not
trying to race any more) is important but there are multiple
adjustments that could be made, like stem height, to make the right
sized frame feel more comfortable. *Is there any good technique
beyond
standing over the top tube and assessing how much space there is
between the bike and the rider to determine if I'm choosing the right
frame size? *There are probably bike shops where I could get more help
with this but I haven't found any yet in my area (Pasadena to Pomona
in LA county, southern California). *Any suggestions? Thanks.

Ken

Find a bike shop that:

will put a bike on a trainer. will take measurements of top tube and
seat tube length. look at how you pedal and make sure that you have a
comfortable position. offers to change stem length. let you ride the
bike for at least an hour. Most modern bike, decent bike stores will
do that. is willing an able to change stem and handlebars for a
minimum price after a month of riding.

if you don't have a bike shop that does this, see if you can drive to
a town nearby that does this.

On Dec 17, 11:25*pm, OccasionalFlyer wrote:
I'm shopping for a new road
bike, with better components than the twenty-year-old 105 components
on my Trek 2100. *The main bikes in the price range I'm aiming for
include a Trek Madone, Cannondale Synapse or Supersix, or Cervelo
(like an R3). *I'm having trouble with finding a bike that fits.
Cannondale and Cervelo both seem to have frame sizes of 51 and 54 but
nothing in-between. My current road bike is 52cm and that feels
right. *I've tried both the 51' with the seat raised and the 54' with
the seat lowered. *The person at the bike store who worked with me
didn't really seem able to say, "You can tell if it's the right frame
size if..." *The 54' is too tall, even with the seat lowered, while
the 51' feels a bit too cramped. *I know that comfort (since I'm not
trying to race any more) is important but there are multiple
adjustments that could be made, like stem height, to make the right
sized frame feel more comfortable. *Is there any good technique
beyond
standing over the top tube and assessing how much space there is
between the bike and the rider to determine if I'm choosing the right
frame size? *There are probably bike shops where I could get more help
with this but I haven't found any yet in my area (Pasadena to Pomona
in LA county, southern California). *Any suggestions? Thanks.

Ken

also, I noticed that you will be buying a pretty high quality and
expensive bike. the bike shop should be able to thoroughly provide
outstanding service in terms of measurements. where do you live?

OccasionalFlyer schreef:
I'm shopping for a new road
bike, with better components than the twenty-year-old 105 components
on my Trek 2100. The main bikes in the price range I'm aiming for
include a Trek Madone, Cannondale Synapse or Supersix, or Cervelo
(like an R3). I'm having trouble with finding a bike that fits.
Cannondale and Cervelo both seem to have frame sizes of 51 and 54 but
nothing in-between. My current road bike is 52cm and that feels
right. I've tried both the 51' with the seat raised and the 54' with
the seat lowered. The person at the bike store who worked with me
didn't really seem able to say, "You can tell if it's the right frame
size if..." The 54' is too tall, even with the seat lowered, while
the 51' feels a bit too cramped. I know that comfort (since I'm not
trying to race any more) is important but there are multiple
adjustments that could be made, like stem height, to make the right
sized frame feel more comfortable. Is there any good technique
beyond
standing over the top tube and assessing how much space there is
between the bike and the rider to determine if I'm choosing the right
frame size? There are probably bike shops where I could get more help
with this but I haven't found any yet in my area (Pasadena to Pomona
in LA county, southern California). Any suggestions? Thanks.

Ken

Your best reference is your current fit. You are attached to the bike
at three points: your feet, your ass and your hands.
Measure
- distance from the top saddle to BB along the seattube,
- horizontal distance from the nose of your saddle to BB,
- vertical distance from top of you saddle to handlebar,
- distance from nose of your current saddle to handlebar.
If you copy these measurements to your new bike the stem should be
between 90 and 120 mm and the exposed seatpost should be between 100
and 200 mm. You willing to spend quite an amount of money. Make sure
you get the right frame. Standover height is the least important
measurent.

Lou

Like others have said, you need to determine the contact points
coordinates of your current bike relative to the bottom bracket, and
make sure you can replicate this on the new bike.

This is assuming that you don't want them to change. If you do (or
might in the future) want them to change, then make sure you can
accommodate that. Stem lengths are readily available from 80-130mm and
have different amounts of rise, handlebars have varying amounts of
reach as well, and seatposts have varying setback. It isn't hard to
make a wide range of sizes fit perfectly.

On 12/18/2011 09:25 AM, Ron Ruff wrote:

Like others have said, you need to determine the contact points
coordinates of your current bike relative to the bottom bracket, and
make sure you can replicate this on the new bike.

This is assuming that you don't want them to change. If you do (or
might in the future) want them to change, then make sure you can
accommodate that. Stem lengths are readily available from 80-130mm and
have different amounts of rise, handlebars have varying amounts of
reach as well, and seatposts have varying setback. It isn't hard to
make a wide range of sizes fit perfectly.

Based on the frame size, I'm probably around the same height as the OP.
I don't want to make a mountain of a molehill but I find it's pretty
difficult to fit people when frames sizes are =52cm.

Fitting is one thing. Getting a great ride is another. I've pretty
much come to the conclusion with 700c wheels (front and back) too many
compromises must be made for small frames/riders.