Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Fitting Your Bike Are you confused about how you should fit a bike to your particular body dimensions? Have you been reading, found the terms Merxx or French Fit, and don’t know what you need? Every style of riding is different- in how you fit the bike to you, and the sizing of the bike itself. It’s more than just measuring your height, reach and inseam. With the help of Bike Fitting, you’ll be able to find the right fit for your frame size, style of riding, and your particular dimensions. Here ya’ go…..the location for everything fit related.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 04-26-14, 12:08 PM   #1
rms13
Senior Member
Thread Starter
 
Join Date: Apr 2013
Location: Santa Clarita, CA
Bikes:
Posts: 6,110
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 65 Post(s)
Question about Lemond Geometry

I am considering picking up a used early 2000s Lemond Buenos Aires. Frame is 53. My current bike is a 54. Current bike is a semi compact modern frame with 545mm effective top tube. I've found that 545mm eff tt is my limit on the small end and 545-555 is my sweet spot from other bikes I've owned and rode.

The person selling the frame says his measurement center seat post to center of head tube is 550mm. To me that sounds like it will fit me but I was looking at the Lemond mechanic's guide guide I found online doesn't list the eff top tube but it says a 53 is good for rider around 68 inches/5'8". I'm 5'10". Do you think the 53 would be way too small for me? I've read something about how seat post angles and stuff on the Lemond make the eff top tube measurements misleading?
rms13 is online now   Reply With Quote
Old 04-26-14, 02:54 PM   #2
chaadster
Thread Killer
 
Join Date: Aug 2008
Location: Ann Arbor, MI
Bikes: '15 Kinesis Racelight 4S, '76 Motebecane Gran Jubilée
Posts: 7,789
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 166 Post(s)
I think the 53cm BA is a 545ETT; this may help: http://www.vintage-trek.com/Trek-Fis...nualLemond.pdf
chaadster is online now   Reply With Quote
Old 04-26-14, 05:16 PM   #3
rms13
Senior Member
Thread Starter
 
Join Date: Apr 2013
Location: Santa Clarita, CA
Bikes:
Posts: 6,110
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 65 Post(s)
Quote:
Originally Posted by chaadster View Post
I think the 53cm BA is a 545ETT; this may help: http://www.vintage-trek.com/Trek-Fis...nualLemond.pdf
Thanks. My current ride is 545mm and 100mm stem so I guess I should be able to make it fit
rms13 is online now   Reply With Quote
Old 04-26-14, 11:38 PM   #4
rms13
Senior Member
Thread Starter
 
Join Date: Apr 2013
Location: Santa Clarita, CA
Bikes:
Posts: 6,110
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 65 Post(s)
I'm getting more confused the more I read. Yes the 53 has a 545mm ETT which is what I have on my current road bike, and the 55 has a 565mm ETT. I have found a 53 and 55 frame for sale. Seems like the 53 would be the way to go but I have read that the Lemonds have shallow seat tube angles so it makes the top tube/reach seem shorter than it actually is. I think 545mm ETT is the shortest I can go so that worries me that the 53 will feel too cramped even if the ETT is the same as on my current frame
rms13 is online now   Reply With Quote
Old 04-27-14, 06:40 AM   #5
chaadster
Thread Killer
 
Join Date: Aug 2008
Location: Ann Arbor, MI
Bikes: '15 Kinesis Racelight 4S, '76 Motebecane Gran Jubilée
Posts: 7,789
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 166 Post(s)
It is confusing, because it's a complicated matter compounded by a lack of precise definition being used. I think there are a couple of important issues to sort that can help bring clarity.

First, the oft repeated and conventional wisdom that Lemonds have long top tubes (TT) and slack seat tubes (ST) is derived from an era in bike design when the majority were shorter and steeper, a situation very different from where we are today. Lemond was an era before sloping TT and before frame size designations lost any connection to actual tube lengths; the old standard was same length TT and ST, so a 56 frame had a 56cm TT and 56cm ST. That is the context within which "Lemond geometry" means something. Today, "Lemond geometry" means nothing, because you find the standard to be something like a size 56 with a 53cm ST and 54.5cm ETT.

Mention of ETT brings us to the definition issue. It needs to be clear, when talking about ST angle (STA), whether one is also talking about keeping TT length and position the same. If TT length and position remain the same, then yes, slackening STA will reduce distance from saddle to head tube (HT) centerline (HTC) because slackening would take place at the bottom bracket (BB) by moving it forward. Think of it this way: the ST/TT junction is the pinned pivot, so to adjust the STA, you swing the bottom, the BB, fore or aft.

Now, the other given is that the rider will have a fixed seat position relative to BB, meaning that if the BB is swung either fore or aft of that ideal relative seat/BB location, the seat will need to follow. Going back to the the slackening ST example, doing so will require the saddle to be pushed forward to maintain the saddle/BB relationship. Remember, the TT length we said was fixed, so of course, moving the saddle further forward effectively shortens the reach distance to HTC.

Of course, TT length and location need not be fixed, so you can slacken (or steepen) STA and keep reach (to HTC) the same by lengthening the TT, steepening the HTA, etc. Because of these variables, it's really most helpful to know your preferred "frame reach," which is the horizontal distance from BB centerline (BBC) to HTC:



Knowing frame reach simplifies things, and removes the necessity of knowing a bunch of other frame dimension and geometry info, and allows for apples-to-apples comparison.

Without knowing more about how Rms13 likes to fit on the bike and having more specific physical dimensions, it's hard to say what will fit and what won't. My recommendation would be to try to compare STA and TT between the bike that fits and the new one, and see how close the reaches are. I know Lemond did not publish reach measurements-- it is becoming more standard today, however-- so short of finding a true to size diagram off which to measure, there's no easy way to do this. I suppose there are frame reach calculators out there, but I've not used one. A quick Google turned up this one: bb2stem: Stack & Reach Calculator v1.00

Hope that helps.
chaadster is online now   Reply With Quote
Old 04-27-14, 09:42 AM   #6
rms13
Senior Member
Thread Starter
 
Join Date: Apr 2013
Location: Santa Clarita, CA
Bikes:
Posts: 6,110
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 65 Post(s)
Thanks Chaadster, very detailed response!

I'm guessing the 53 would be the better fit for me.

my current bike: 543 ETT , 73 HT, 73.7 ST
53 lemond: 545 ETT, 73 HT, 73 ST

Seems like it's close enough that I should be able to make it fit with saddle fore/aft and stem height and length adjustments better than going with the 55.

I think people have gotten used to smaller frames these days to so theory on fit is different. When I look at old forum posts from when these bikes were current people with pretty similar measurements to me where going with 55 and even 57 Lemonds. A lot of personal preference I guess.
rms13 is online now   Reply With Quote
Old 04-27-14, 08:14 PM   #7
Weatherby
Registered User
 
Join Date: Mar 2014
Location: Mid-Atlantic
Bikes: Too many
Posts: 548
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by chaadster View Post
It is confusing, because it's a complicated matter compounded by a lack of precise definition being used. I think there are a couple of important issues to sort that can help bring clarity.

First, the oft repeated and conventional wisdom that Lemonds have long top tubes (TT) and slack seat tubes (ST) is derived from an era in bike design when the majority were shorter and steeper, a situation very different from where we are today. Lemond was an era before sloping TT and before frame size designations lost any connection to actual tube lengths; the old standard was same length TT and ST, so a 56 frame had a 56cm TT and 56cm ST. That is the context within which "Lemond geometry" means something. Today, "Lemond geometry" means nothing, because you find the standard to be something like a size 56 with a 53cm ST and 54.5cm ETT.

Mention of ETT brings us to the definition issue. It needs to be clear, when talking about ST angle (STA), whether one is also talking about keeping TT length and position the same. If TT length and position remain the same, then yes, slackening STA will reduce distance from saddle to head tube (HT) centerline (HTC) because slackening would take place at the bottom bracket (BB) by moving it forward. Think of it this way: the ST/TT junction is the pinned pivot, so to adjust the STA, you swing the bottom, the BB, fore or aft.

Now, the other given is that the rider will have a fixed seat position relative to BB, meaning that if the BB is swung either fore or aft of that ideal relative seat/BB location, the seat will need to follow. Going back to the the slackening ST example, doing so will require the saddle to be pushed forward to maintain the saddle/BB relationship. Remember, the TT length we said was fixed, so of course, moving the saddle further forward effectively shortens the reach distance to HTC.

Of course, TT length and location need not be fixed, so you can slacken (or steepen) STA and keep reach (to HTC) the same by lengthening the TT, steepening the HTA, etc. Because of these variables, it's really most helpful to know your preferred "frame reach," which is the horizontal distance from BB centerline (BBC) to HTC:



Knowing frame reach simplifies things, and removes the necessity of knowing a bunch of other frame dimension and geometry info, and allows for apples-to-apples comparison.

Without knowing more about how Rms13 likes to fit on the bike and having more specific physical dimensions, it's hard to say what will fit and what won't. My recommendation would be to try to compare STA and TT between the bike that fits and the new one, and see how close the reaches are. I know Lemond did not publish reach measurements-- it is becoming more standard today, however-- so short of finding a true to size diagram off which to measure, there's no easy way to do this. I suppose there are frame reach calculators out there, but I've not used one. A quick Google turned up this one: bb2stem: Stack & Reach Calculator v1.00

Hope that helps.
And you wonder why people pay to get fit?
Weatherby is offline   Reply With Quote
Old 04-28-14, 01:40 AM   #8
chaadster
Thread Killer
 
Join Date: Aug 2008
Location: Ann Arbor, MI
Bikes: '15 Kinesis Racelight 4S, '76 Motebecane Gran Jubilée
Posts: 7,789
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 166 Post(s)
Quote:
Originally Posted by Weatherby View Post
And you wonder why people pay to get fit?
Oh my god, we haven't even gotten to the fitting part yet, buddy!
chaadster is online now   Reply With Quote
Old 04-28-14, 09:43 AM   #9
bikebreak
Senior Member
 
Join Date: Jun 2012
Bikes:
Posts: 595
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
I have found people selling frames online or CL often mis-measure top tube, especially in sloping TT frames.
If it is a close call, look up the geo chart and get the seller to measure the head tube to confirm frame size. It's much harder to botch that one.

If it works, enjoy the Lemond, they are super
bikebreak is offline   Reply With Quote
Old 05-09-14, 02:05 PM   #10
equinoxranch
Junior Member
 
equinoxranch's Avatar
 
Join Date: May 2014
Bikes:
Posts: 15
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
"I'm getting more confused the more I read. Yes the 53 has a 545mm ETT which is what I have on my current road bike, and the 55 has a 565mm ETT. I have found a 53 and 55 frame for sale. Seems like the 53 would be the way to go but I have read that the Lemonds have shallow seat tube angles so it makes the top tube/reach seem shorter than it actually is...................."

RMS.................. No, the shallower - (more relaxed) seat angle, or greater set back effectively increases tt length.


LeMond's formula, in fact that of Guimard places greater position behind the pedal, not above, utilizing greater physiological power (leverage) by using more muscle groups evenly and efficiently. The greater set back is beneficial to a greater number of cyclists on average.
Think about it.
equinoxranch is offline   Reply With Quote
Old 05-09-14, 03:34 PM   #11
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Bikes: 7
Posts: 19,561
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 416 Post(s)
DIY OPINION FORMING .. Go find bikes in a shop and stand over them ..

ride it around the block , bring a tape measure and write down the numbers .
fietsbob is offline   Reply With Quote
Old 05-11-14, 08:13 AM   #12
Road Fan
Senior Member
 
Road Fan's Avatar
 
Join Date: Apr 2005
Location: Ann Arbor, MI
Bikes:
Posts: 12,290
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 24 Post(s)
Quote:
Originally Posted by rms13 View Post
Thanks Chaadster, very detailed response!

I'm guessing the 53 would be the better fit for me.

my current bike: 543 ETT , 73 HT, 73.7 ST
53 lemond: 545 ETT, 73 HT, 73 ST

Seems like it's close enough that I should be able to make it fit with saddle fore/aft and stem height and length adjustments better than going with the 55.

I think people have gotten used to smaller frames these days to so theory on fit is different. When I look at old forum posts from when these bikes were current people with pretty similar measurements to me where going with 55 and even 57 Lemonds. A lot of personal preference I guess.
How did you get that your current bike has a 73.7 degree seat tube angle? If true, then your existing bike has a setback of 15.2 cm assuming a seat tube length of 54 cm. With your 54.5 cm ETT, the reach is 39.3 cm.

I think you also said the LeMond is 53 cm, 73 seat tube angle, and 54.3 cm ETT. So then the setback at 53 cm is 15.5 cm, 3 mm longer than for your current bike. With the LeMond top tube of 54.3 cm, it's reach is 38.8 cm, just 5 mm shorter than for your current bike.

As sizing goes, these are very very close to each other. I would not worry buying the LeMond. You can compensate any short reach issues with a stem 1 centimeter longer.

Last edited by Road Fan; 05-11-14 at 12:10 PM.
Road Fan is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 12:43 AM.