Advice on best frame size for me



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T

Tim McNamara

Guest
"death" <[email protected]*.no*spam> writes:

>> Basically, this is going to put you about 1.5 cm or so ahead of your "ideal" fit.
>
> Please bear with me, I obviously did not pay close enough attention in geometry class. I'm not
> sure what you mean by "ahead."

Think of the seat tube as a rotating arm, measuring the angle from the horizontal behind the bottom
bracket. The steeper the angle, the farther forward the top of the seat tube. If your ideal is 73.5,
then a 75 will put you about farther ahead of the bottom bracket.

If you haven't read:

http://www.sheldonbrown.com/frame-sizing.html and

http://www.rivendellbicycles.com/html/rr_comfposition.html

you should. There are other good sites for information about frame geometry, too. With diagrams this
becomes instantly obvious.

> http://www.somafab.com/geometry03.html
>
> The frame I am interested in is called the "Rush," the numbers are at the bottom of the page.

Yup, that's pretty much designed like a dedicated track bike. I won't dissuade you from it because,
as I mentioned, I like riding a track bike. It's fun.

>> I'm curious- why are you buying this frame rather than one that fits?
>
> Well, I am considering buying this frame because I thought it got closest to the measurements I
> was looking for while best meeting a couple of other requirements I have. These other requirements
> are somewhat simple, I would like the frame to be made of steel and I am looking for a total bike
> cost of $1,200-$1,500 which puts the frame into the Made in Taiwan range.

Consider a Rivendell Quickbeam:

http://rivendellbicycles.com/webalog/frames/50150.html

> I looked very closely at Soma, Surly, Bianchi, KHS & Fuji. The Soma and Bianchi frames have
> nearly(if not exactly) the same geometry: Bianchi Pista: (it is worth noting that SB does a better
> job providing information on the Harris Cyclery site about this bike than Bianchi does on their US
> web site).

This is par for the course. Sheldon is a smart guy and very thorough. He loves what he
does, I think.

Also consider a Kogswell (www.kogswell.com)

> I know that I could convert a road bike to fixed, but that does not really appeal to me. I like
> the aesthetic of a track bike(but I am going to use brakes). Perhaps that sounds shallow, but I
> need to be attracted to the bike if I am going to spend a lot of time with it(the first time I saw
> my reflection in the chrome of an 04 Bianchi Pista my wallet started to itch).

Not shallow at all. You do have to like the bike, to be drawn to it, in order to get out and ride
it. Shoot, that's why many of us have multiple bikes- at least one calls to us every day!
 
A

Arthur Harris

Guest
"death" wrote:

> The Soma frames have a 75.3 degree seat tube angle on their 57 frames, a
75
> degree angle on their 59. The measurement of "ideal" frame is 73.5
degrees.

> How do you determine how much length the sharper angle adds to the top tube/stem measurement?

Trigonometry. The slacker the seat tube angle, the further back the seat post will be relative to
the BB. Multiply the distance from the BB to the top of the seat post by the cosine of the seat tube
angle to determine how far the seat tube will be behind the BB.

The saddle fore/aft position relative to the BB is adjusted using KOPS or your favorite alternative.
Regardless of the seat tube angle, your saddle must be adjusted for this ideal position relative to
the BB. If the seat tube angle is very steep, you will have the slide the saddle back to get the
proper fore/aft position. That "effectively" lengthens the top tube. That's why I used the term
"effective top tube length."

> Also, the ideal frame has a 73.5 degree head tube angle. The Soma frames have a 74.3 degree head
> angle on the 57 and a 75 degree head angle on the 59. If the seat tube angle adds length in the
> comparison would the sharper head angle not subtract length in the same
way?

No. We're talking about "effective" TT length not actual.

The ideal seat tube angle depends on your thigh bone (femur) length. If you have a relatively short
femur (for your height) you need a steep seat tube angle (and vice versa).

If Serotta determined that your ideal seat angle is 73.5 why are you considering a frame with a 75.3
degree angle? The starting point for proper fit is saddle height and fore/aft position. If your seat
tube angle is too steep, you will have to shove the seat way back. That makes the reach to the bars
longer (i.e., increases the "effective top tube length").

Art "cosine theta" Harris
 
P

Phil Holman

Guest
"Tim McNamara" <[email protected]> wrote in message news:[email protected]...
> "death" <[email protected]*.no*spam> writes:
>
> > Thanks for the response. I'm 36. It was determined during my fitting that I will be better off
> > using a lot(3cm) of stem spacers and 10 degree rise stem.
>
> Sounds like you need the higher bars. But I'm a little baffled by this clearance issue. You say
> you're 6'1"? I'm 6'4" and about a 63 cm frame (center to top) fits me pretty well. Seems to me
> like you should be able to ride a 60 cm frame without any problem, unless it's got a *really* high
> bottom bracket.
>
> It's better to compensate for a slightly too-long top tube with a shorter stem than vice versa.
> Long stems start to have deleterious effects on handling, IMHO. It's the "tiller" effect.

I'm at the other end of the spectrum when it comes to frame size. I'm 6' 2" and ride a 57cm. I like
to have the handlebars 15cm below the seat which is difficult on a larger frame. I have a saddle
nose to handlebar dimension of 61cm (130mm stem) and a BB to saddletop dimension of 80cm requiring a
270mm seatpost. This is my racing setup so I duplicate this on my road racing, track and training
bikes. My rainbike is a little higher on the front being an older 60cm frame.

Phil Holman
 
D

Death

Guest
> Basically, this is going to put you about 1.5 cm or so ahead of your "ideal" fit.

Please bear with me, I obviously did not pay close enough attention in geometry class. I'm not sure
what you mean by "ahead." I was under the impression that with the larger size(59) of the frame that
I am considering I would putting my comfortable posture further away from the bars than on a frame
with a shorter top tube. With the goal of reaching the measurements calculated in my fitting I would
compensate for this by using a very short stem. This is something that I would define as "behind."
Where did the 1.5 cm go? Or are you working off the size 57 frame?

Track bikes tend to have steep head and seat tube
> angles and shallow offset forks (with a 75 degree head tube, you'll want a fork with about 35 mm
> of offset, sometimes called rake. Not so easy to find, I hope the frame comes with a fork).

The frame does have an optional fork(which I was planning on buying), but the fork offset
measurement is not detailed in the geometry chart on their web site. If you are interested you can
view the specs here:

http://www.somafab.com/geometry03.html

The frame I am interested in is called the "Rush," the numbers are at the bottom of the page.

> I'm curious- why are you buying this frame rather than one that fits?

Well, I am considering buying this frame because I thought it got closest to the measurements I was
looking for while best meeting a couple of other requirements I have. These other requirements are
somewhat simple, I would like the frame to be made of steel and I am looking for a total bike cost
of $1,200-$1,500 which puts the frame into the Made in Taiwan range. I looked very closely at Soma,
Surly, Bianchi, KHS & Fuji. The Soma and Bianchi frames have nearly(if not exactly) the same
geometry: Bianchi Pista: http://www.sheldonbrown.com/harris/bianchi04/pistase.html (it is worth
noting that SB does a better job providing information on the Harris Cyclery site about this bike
than Bianchi does on their US web site). Surly has a nice frame, the Steamroller, but the
measurements do not seem to get close to what I am looking for. I did not think the KHS or Fuji
frames got closer in the numbers than the Soma, but I am going to go back and look a little closer.
I have seen examples of all these frames(though not in my size) and the Soma gives me the impression
that they have a very good price vs. value thing going on; they use Reynolds 631 front & butted
rear, decent finish, welds etc. I have a boutique mountain bike frame that was not clear coated over
the decals, Soma frames are. At $650 the Bianchi Pista is an excellent deal for a full bike, but I
want to go a step up with the components. Today I looked at the specs of the Gunnar track/single
speed/road frame. It is a lot closer to what I was fitted for in terms of geometry & it is made in
America, Reynolds 853. It also costs more than 2x the Soma f/f.

I know that I could convert a road bike to fixed, but that does not really appeal to me. I like the
aesthetic of a track bike(but I am going to use brakes). Perhaps that sounds shallow, but I need to
be attracted to the bike if I am going to spend a lot of time with it(the first time I saw my
reflection in the chrome of an 04 Bianchi Pista my wallet started to itch). In a perfect world I
would find an interesting older bike that fit right, but I have been looking for a few months and I
am getting anxious. I have had a track bike on my to do list for maybe ten years but it has only
been somewhat recently that I moved from a very big city to a place where I feel I can comfortably
explore the fixed gear learning curve(by coincidence, it seems like the bike industry happens to be
suddenly paying attention to my list). Until now I never felt ready to add more complexity to the
usual mortal ante required when you decide to use a bicycle to travel the same roads that the
gazillion other commuters, delivery vehicles, taxis, busses, bicycle messengers etc use as a
shortcut when they are running late on their way to the criminal insanity convention. Now I have a
little more recreational cash, storage space & time to ride weird bikes.
 
D

Death

Guest
> > How do you determine how much length the sharper angle adds to the top tube/stem measurement?
>
> Trigonometry. The slacker the seat tube angle, the further back the seat post will be relative to
> the BB. Multiply the distance from the BB to the top of the seat post by the cosine of the seat
> tube angle to determine how far the seat tube will be behind the BB.

Thank you. That makes sense. I own a calculator that has a cosine function, I can probably make
this work.

>
> The saddle fore/aft position relative to the BB is adjusted using KOPS or your favorite
> alternative. Regardless of the seat tube angle, your saddle must be adjusted for this ideal
> position relative to the BB. If the seat tube angle is very steep, you will have the slide the
> saddle back to get
the
> proper fore/aft position. That "effectively" lengthens the top tube.
That's
> why I used the term "effective top tube length."

Understood. I probably did not understand this before now, as obvious as it is, but I get it.

>
> > Also, the ideal frame has a 73.5 degree head tube angle. The Soma frames have a 74.3 degree head
> > angle on the 57 and a 75 degree head angle on the 59. If the seat tube angle adds length in the
> > comparison would the sharper head angle not subtract length in the same
> way?
>
> No. We're talking about "effective" TT length not actual.
>
> The ideal seat tube angle depends on your thigh bone (femur) length. If
you
> have a relatively short femur (for your height) you need a steep seat tube angle (and vice versa).

That also helps.

>
> If Serotta determined that your ideal seat angle is 73.5 why are you considering a frame with a
> 75.3 degree angle? The starting point for
proper
> fit is saddle height and fore/aft position. If your seat tube angle is too steep, you will have to
> shove the seat way back. That makes the reach to
the
> bars longer (i.e., increases the "effective top tube length").

Well, I'm not really sure it is fair to say that Serotta determined my ideal seat angle. I went to a
local shop that is a Serotta dealer. The tech that measured me was trained by Serotta to use their
system, but they sell other brands. I had the impression that the information generated by this
process could be applied to a stock frame(that is what the owner of the bike shop told me when I
asked). It was my intention to buy the bike I am discussing now from this shop but they ended up not
wanting to do a single speed road bike. It is my assumption(perhaps wrong) that different frame
angles are used based on the application of the bicycle. For instance a "touring" frame will have
slacker angles than a "performance" or "racing" frame. I have(had) the impression that the
measurements of the tubes could be made to compensate for body size around the angles appropriate to
the application of the bike. I'm not in the financial position to commission a custom frame(However,
at this point I have spent enough time thinking about it that it I could justify the cost. To
myself, anyway.). I am interested in a single speed road bike, most of them have "track racing"
angles, so here I am, thinking that I can find a frame close to the numbers I bought from the shop
that did the fitting service.

It is silly of me to think that there is a shortcut through this process, I just need to try
different things until I get what works for me. I enjoy bikes, it will be fun.
 
A

Art Harris

Guest
"death" wrote:

> Well, I'm not really sure it is fair to say that Serotta determined my ideal seat angle. I went to
> a local shop that is a Serotta dealer. The tech that measured me was trained by Serotta to use
> their system, but they sell other brands.

Determining ideal seat angle should be part of the fit process. Read Peter Chisholm's many posts on
this subject. (Google Groups search: "femur" "seat tube angle" "Chisholm")

> I had the impression that the information generated by this process could be applied to a stock
> frame(that is what the owner of the bike shop told me when I asked).

Yes, you would search for a stock frame that comes close to your ideal fit, rather than buying a
custom frame. The Soma doesn't seem to be a good match.

> It is my assumption(perhaps wrong) that different frame angles are used based on the application
> of the bicycle. For instance a "touring" frame will have slacker angles than a "performance" or
> "racing" frame.

In general that is true. But I think that derives mostly from the head tube angle. As Jobst has
pointed out, head angles are chosen with typical road irregularities in mind such that the fork sees
primarily axial compression when you hit a bump. As roads have become smoother, head angles have
gotten steeper. On the track, there are NO irregularities, so track bikes have very steep head
angles. Also, track events tend to be short so comfort is not as much a concern as for a road bike.

Once the head angle is chosen, the seat angle is usually set within a degree of the head angle.

> I had the impression that the measurements of the tubes could be made to compensate for body size
> around the angles appropriate to the application of the bike.

Not exactly sure what you mean by that. But, yes, if you can't find exactly the right frame
dimensions, you can compensate somewhat. But since you haven't bought the frame yet, I think you
ought to keep looking until you find something closer to ideal.

> I'm not in the financial position to commission a custom frame(However, at this point I have spent
> enough time thinking about it that it I could justify the cost. To myself, anyway.). I am
> interested in a single speed road bike, most of them have "track racing" angles, so here I am,
> thinking that I can find a frame close to the numbers I bought from the shop that did the fitting
> service.

Lots of guys build up fixies and single speeds using old "sport touring" frames purchased on eBay or
thrift shops. Those frames usually have relatively slack angles and long wheelbases. I assume you're
going to be using the bike on the road. The high BB on track bikes is designed for pedaling a fixed
gear around the banked track.

Art Harris
 
D

Death

Guest
"Qui si parla Campagnolo" <[email protected]> wrote in message
news:[email protected]...
> death-<< The seat tube angle of the "ideal" frame is 73.5 degrees. The
Soma
> frames have a 75.3 degree seat tube angle on the 57, and a 75.0 on the 59.
>><BR><BR>
>
> Are they really that steep??

Well, that is what their web site says:

http://www.somafab.com/geometry03.html

The numbers for the Rush(track) frame are at the bottom of the page.

>
> So, if the 'ideal' is 73.5mm, then on a 75mm, you would need to move your saddle back 'about'
> 1.5cm, to get the KOPS-effectively increasing the top
tube
> length the same-for the 75.3, 1.8cm-

Thanks for the help with this, I think I get it now.
 
M

Matt O'Toole

Guest
It jus so happens there's a Gunnar Street Dog on eBay right now, about your size. I came across it
last night, while just looking around. You could get a whole bike for less than the cost of a
frame. There's no reserve, and a bike like this could easily go unnoticed by bidders, especially
this time of year.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3644004482&category=7298&rd=1

With luck, you might get it for $301.00! Probably not now that I've posted this, but that's what you
get for obscuring your email address...

Matt O.

"death" <[email protected]*.no*spam> wrote in message
news:p[email protected]...
> > Basically, this is going to put you about 1.5 cm or so ahead of your "ideal" fit.
>
> Please bear with me, I obviously did not pay close enough attention in geometry class. I'm not
> sure what you mean by "ahead." I was under the impression that with the larger size(59) of the
> frame that I am considering I would putting my comfortable posture further away from the bars than
> on a frame with a shorter top tube. With the goal of reaching the measurements calculated in my
> fitting I would compensate for this by using a very short stem. This is something that I would
> define as "behind." Where did the 1.5 cm go? Or are you working off the size 57 frame?
>
> Track bikes tend to have steep head and seat tube
> > angles and shallow offset forks (with a 75 degree head tube, you'll want a fork with about 35 mm
> > of offset, sometimes called rake. Not so easy to find, I hope the frame comes with a fork).
>
> The frame does have an optional fork(which I was planning on buying), but the fork offset
> measurement is not detailed in the geometry chart on their web site. If you are interested you can
> view the specs here:
>
> http://www.somafab.com/geometry03.html
>
> The frame I am interested in is called the "Rush," the numbers are at the bottom of the page.
>
> > I'm curious- why are you buying this frame rather than one that fits?
>
> Well, I am considering buying this frame because I thought it got closest to the measurements I
> was looking for while best meeting a couple of other requirements I have. These other requirements
> are somewhat simple, I would like the frame to be made of steel and I am looking for a total bike
> cost of $1,200-$1,500 which puts the frame into the Made in Taiwan range. I looked very closely at
> Soma, Surly, Bianchi, KHS & Fuji. The Soma and Bianchi frames have nearly(if not exactly) the same
> geometry: Bianchi Pista: http://www.sheldonbrown.com/harris/bianchi04/pistase.html (it is worth
> noting that SB does a better job providing information on the Harris Cyclery site about this bike
> than Bianchi does on their US web site). Surly has a nice frame, the Steamroller, but the
> measurements do not seem to get close to what I am looking for. I did not think the KHS or Fuji
> frames got closer in the numbers than the Soma, but I am going to go back and look a little
> closer. I have seen examples of all these frames(though not in my size) and the Soma gives me the
> impression that they have a very good price vs. value thing going on; they use Reynolds 631 front
> & butted rear, decent finish, welds etc. I have a boutique mountain bike frame that was not clear
> coated over the decals, Soma frames are. At $650 the Bianchi Pista is an excellent deal for a full
> bike, but I want to go a step up with the components. Today I looked at the specs of the Gunnar
> track/single speed/road frame. It is a lot closer to what I was fitted for in terms of geometry &
> it is made in America, Reynolds 853. It also costs more than 2x the Soma f/f.
>
> I know that I could convert a road bike to fixed, but that does not really appeal to me. I like
> the aesthetic of a track bike(but I am going to use brakes). Perhaps that sounds shallow, but I
> need to be attracted to the bike if I am going to spend a lot of time with it(the first time I saw
> my reflection in the chrome of an 04 Bianchi Pista my wallet started to itch). In a perfect world
> I would find an interesting older bike that fit right, but I have been looking for a few months
> and I am getting anxious. I have had a track bike on my to do list for maybe ten years but it has
> only been somewhat recently that I moved from a very big city to a place where I feel I can
> comfortably explore the fixed gear learning curve(by coincidence, it seems like the bike industry
> happens to be suddenly paying attention to my list). Until now I never felt ready to add more
> complexity to the usual mortal ante required when you decide to use a bicycle to travel the same
> roads that the gazillion other commuters, delivery vehicles, taxis, busses, bicycle messengers etc
> use as a shortcut when they are running late on their way to the criminal insanity convention. Now
> I have a little more recreational cash, storage space & time to ride weird bikes.
 
D

Death

Guest
"Tim McNamara" <[email protected]> wrote in message news:[email protected]...
> "death" <[email protected]*.no*spam> writes:
>
> >> Basically, this is going to put you about 1.5 cm or so ahead of your "ideal" fit.
> >
> > Please bear with me, I obviously did not pay close enough attention in geometry class. I'm not
> > sure what you mean by "ahead."
>
> Think of the seat tube as a rotating arm, measuring the angle from the horizontal behind the
> bottom bracket. The steeper the angle, the farther forward the top of the seat tube. If your ideal
> is 73.5, then a 75 will put you about farther ahead of the bottom bracket.
>
I have it now, I was not understanding seat tube angle correctly. Thanks for taking the
time to help.
 
D

Death

Guest
Thanks for the heads up, I actually saw that listing right after I posted that message mentioning
Gunnar. Yhis one is a 60, I have my eye on it, but the size 58 Street Dog gets the numbers I am
looking for almost exactly right.

"Matt O'Toole" <[email protected]> wrote in message news:[email protected]...
> It jus so happens there's a Gunnar Street Dog on eBay right now, about your size. I came across it
> last night, while just looking around. You could get a whole bike for less than the cost of a
> frame. There's no reserve, and a bike like this could easily go unnoticed by bidders, especially
> this time of year.
>
>
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3644004482&category=7298&rd=1
>
> With luck, you might get it for $301.00! Probably not now that I've
posted
> this, but that's what you get for obscuring your email address...
>
> Matt O.
>
> "death" <[email protected]*.no*spam> wrote in message
> news:p[email protected]...
> > > Basically, this is going to put you about 1.5 cm or so ahead of your "ideal" fit.
> >
> > Please bear with me, I obviously did not pay close enough attention in geometry class. I'm not
> > sure what you mean by "ahead." I was under the impression that with the larger size(59) of the
> > frame that I am
considering
> > I would putting my comfortable posture further away from the bars than
on a
> > frame with a shorter top tube. With the goal of reaching the
measurements
> > calculated in my fitting I would compensate for this by using a very
short
> > stem. This is something that I would define as "behind." Where did the
1.5
> > cm go? Or are you working off the size 57 frame?
> >
> > Track bikes tend to have steep head and seat tube
> > > angles and shallow offset forks (with a 75 degree head tube, you'll want a fork with about 35
> > > mm of offset, sometimes called rake. Not so easy to find, I hope the frame comes with a fork).
> >
> > The frame does have an optional fork(which I was planning on buying),
but
> > the fork offset measurement is not detailed in the geometry chart on
their
> > web site. If you are interested you can view the specs here:
> >
> > http://www.somafab.com/geometry03.html
> >
> > The frame I am interested in is called the "Rush," the numbers are at
the
> > bottom of the page.
> >
> > > I'm curious- why are you buying this frame rather than one that fits?
> >
> > Well, I am considering buying this frame because I thought it got
closest to
> > the measurements I was looking for while best meeting a couple of other requirements I have.
> > These other requirements are somewhat simple, I
would
> > like the frame to be made of steel and I am looking for a total bike
cost of
> > $1,200-$1,500 which puts the frame into the Made in Taiwan range. I
looked
> > very closely at Soma, Surly, Bianchi, KHS & Fuji. The Soma and Bianchi frames have nearly(if not
> > exactly) the same geometry: Bianchi Pista:
> > http://www.sheldonbrown.com/harris/bianchi04/pistase.html (it is worth noting that SB does a
> > better job providing information on the Harris
Cyclery
> > site about this bike than Bianchi does on their US web site). Surly has
a
> > nice frame, the Steamroller, but the measurements do not seem to get
close
> > to what I am looking for. I did not think the KHS or Fuji frames got
closer
> > in the numbers than the Soma, but I am going to go back and look a
little
> > closer. I have seen examples of all these frames(though not in my size)
and
> > the Soma gives me the impression that they have a very good price vs.
value
> > thing going on; they use Reynolds 631 front & butted rear, decent
finish,
> > welds etc. I have a boutique mountain bike frame that was not clear
coated
> > over the decals, Soma frames are. At $650 the Bianchi Pista is an
excellent
> > deal for a full bike, but I want to go a step up with the components.
Today
> > I looked at the specs of the Gunnar track/single speed/road frame. It is
a
> > lot closer to what I was fitted for in terms of geometry & it is made in America, Reynolds 853.
> > It also costs more than 2x the Soma f/f.
> >
> > I know that I could convert a road bike to fixed, but that does not
really
> > appeal to me. I like the aesthetic of a track bike(but I am going to use brakes). Perhaps that
> > sounds shallow, but I need to be attracted to the
bike
> > if I am going to spend a lot of time with it(the first time I saw my reflection in the chrome of
> > an 04 Bianchi Pista my wallet started to
itch).
> > In a perfect world I would find an interesting older bike that fit
right,
> > but I have been looking for a few months and I am getting anxious. I
have
> > had a track bike on my to do list for maybe ten years but it has only
been
> > somewhat recently that I moved from a very big city to a place where I
feel
> > I can comfortably explore the fixed gear learning curve(by coincidence,
it
> > seems like the bike industry happens to be suddenly paying attention to
my
> > list). Until now I never felt ready to add more complexity to the usual mortal ante required
> > when you decide to use a bicycle to travel the same roads that the gazillion other commuters,
> > delivery vehicles, taxis,
busses,
> > bicycle messengers etc use as a shortcut when they are running late on
their
> > way to the criminal insanity convention. Now I have a little more recreational cash, storage
> > space & time to ride weird bikes.
> >
>
 
D

Death

Guest
Thanks for the pointer to the Usenet search on the seat tube angles, I think I finally have the info
I need to feel comfortable making a decision about a frame.

"Art Harris" <[email protected]> wrote in message
news:[email protected]...
> "death" wrote:
>
> > Well, I'm not really sure it is fair to say that Serotta determined my
ideal
> > seat angle. I went to a local shop that is a Serotta dealer. The tech
that
> > measured me was trained by Serotta to use their system, but they sell
other
> > brands.
>
> Determining ideal seat angle should be part of the fit process. Read Peter Chisholm's many posts
> on this subject. (Google Groups search: "femur" "seat tube angle" "Chisholm")
>
> > I had the impression that the information generated by this process could be applied to a stock
> > frame(that is what the owner of the bike
shop
> > told me when I asked).
>
> Yes, you would search for a stock frame that comes close to your ideal fit, rather than buying a
> custom frame. The Soma doesn't seem to be a good match.
>
> > It is my assumption(perhaps wrong) that different frame angles are used based on the application
> > of the bicycle. For instance a "touring" frame will have slacker angles than a "performance" or
> > "racing" frame.
>
> In general that is true. But I think that derives mostly from the head tube angle. As Jobst has
> pointed out, head angles are chosen with typical road irregularities in mind such that the fork
> sees primarily axial compression when you hit a bump. As roads have become smoother, head angles
> have gotten steeper. On the track, there are NO irregularities, so track bikes have very steep
> head angles. Also, track events tend to be short so comfort is not as much a concern as for a
> road bike.
>
> Once the head angle is chosen, the seat angle is usually set within a degree of the head angle.
>
> > I had the impression that the measurements of the tubes could be made to compensate for body
> > size around the angles appropriate to the
application of
> > the bike.
>
> Not exactly sure what you mean by that. But, yes, if you can't find exactly the right frame
> dimensions, you can compensate somewhat. But since you haven't bought the frame yet, I think you
> ought to keep looking until you find something closer to ideal.
>
> > I'm not in the financial position to commission a custom frame(However, at this point I have
> > spent enough time thinking about it
that
> > it I could justify the cost. To myself, anyway.). I am interested in a single speed road bike,
> > most of them have "track racing" angles, so here
I
> > am, thinking that I can find a frame close to the numbers I bought from
the
> > shop that did the fitting service.
>
> Lots of guys build up fixies and single speeds using old "sport touring" frames purchased on eBay
> or thrift shops. Those frames usually have relatively slack angles and long wheelbases. I assume
> you're going to be using the bike on the road. The high BB on track bikes is designed for pedaling
> a fixed gear around the banked track.
>
> Art Harris
 
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