Stem length math help-completely lost
07-12-11 | 07:49 AM
#26
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From: A Coffin Called Earth. or Toronto, ON
Bikes: Bianchi, Miyata, Dahon, Rossin
there's no way to get an effective/horizontal top tube length below 53.5cm on 700c bikes, because if it's any smaller, then the HTA and STA will be simply wrong as a road bike.
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Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
07-12-11 | 05:54 PM
#27
Over the hill
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From: Los Angeles, CA
Bikes: Pinarello Nytro, Momentum Transend
Check out trek and cervelo, both used to and i think still do quote reach as do many others but not all.
Saddle position (set back ) is determined relative to the bottom bracket to get your knees at a comfortable angle and to get your ballance correct. Stand up and assume a riding position with your arms out forward - you are ballanced and have no weight supported on your arms. You can reach further forward if you want by re ballancing, or sit up more too if you like with no weight supported by your arms. On the bike your seat position determines your ballance point. too far forward and you must support yourself on your arms so saddle position does effect stem length. opposite to what you might expect, moving the seat back often ballences you so a longer stem is more comfortable
However the reach of a frame is independant of setback, you could get the set back such that you are comfortably ballanced but the front triangle of the frame is so long you cant reach the bars at all. Notice that adding spacers under the stam results in the stem getting closer to the BB as does flipping up the stem.
FWIW I can get comfortable with anything between a 90mm and 120mm stem by altering my ballance, seat back = longer stem, it just depends how much you want to be leaning forward when you are ballanced, the more you lean forward the more your back has to do. i ended up settling for a 110 stem as that position suits the riding i do. others may be different
Saddle position (set back ) is determined relative to the bottom bracket to get your knees at a comfortable angle and to get your ballance correct. Stand up and assume a riding position with your arms out forward - you are ballanced and have no weight supported on your arms. You can reach further forward if you want by re ballancing, or sit up more too if you like with no weight supported by your arms. On the bike your seat position determines your ballance point. too far forward and you must support yourself on your arms so saddle position does effect stem length. opposite to what you might expect, moving the seat back often ballences you so a longer stem is more comfortable
However the reach of a frame is independant of setback, you could get the set back such that you are comfortably ballanced but the front triangle of the frame is so long you cant reach the bars at all. Notice that adding spacers under the stam results in the stem getting closer to the BB as does flipping up the stem.
FWIW I can get comfortable with anything between a 90mm and 120mm stem by altering my ballance, seat back = longer stem, it just depends how much you want to be leaning forward when you are ballanced, the more you lean forward the more your back has to do. i ended up settling for a 110 stem as that position suits the riding i do. others may be different
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07-12-11 | 06:08 PM
#28
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In the old language you're five foot 6? You list your height as 68 inches, with a 32 inch inseam? If you're five six you are on a bike that is too big for you. I'm five eleven, 182 cm and on a 56cm frame, with a 120 mm stem. You would want a frame around 52 - 54 cm tt. Unless I'm wrong strip the bike for parts and get a smaller frame.
07-12-11 | 06:13 PM
#29
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The bike is a 56cm frame and I know it is a no no to ever buy a bike not knowing if it fits you but I wanted to get into road biking and a friend of mine had this bike and let me have it for 150 bucks. So I didnt think I would find a better deal than a Trek 1000 for that price so I had to go for it, figured I could ride it and get some base miles under me and the fit felt to close not to grab it. I've done a few 50 mile plus rides on it so far and it feels fine other than anything above 10 miles kills my left elbow when I stop. Its not a constant pain but only when I move my arm a certain way or try to stretch it out completely. Alot like tennis elbow I would imagine. Anyways, the pain is there the rest of the day as I described but once I sleep and wake up and everything is back to normal the next day until I ride. I've checked handlebar width,fore/aft position,saddle height and all of those seem to spot on. So last option is the stem to check out and if that didnt help then I would just bite the cost and save for a pro fit to be done with the matter.
07-12-11 | 06:16 PM
#30
Ridin' South Cackalacky
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07-12-11 | 06:31 PM
#31
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From: Jonesboro AR
Bikes: Trek
Ah, crap sorry Minion I knew it would be something like human error. I am actually 5'8 and a half and just typed in the wrong inch measurment. But since a picture is worth a thousand words I took a few today that might help give an idea of my size and the bike size. I had already rode for the day so I just threw it up on the trainer outside before dark. Thats why I am in street clothes. 
07-12-11 | 06:38 PM
#32
Ridin' South Cackalacky
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Ah, crap sorry Minion I knew it would be something like human error. I am actually 5'8 and a half and just typed in the wrong inch measurment. But since a picture is worth a thousand words I took a few today that might help give an idea of my size and the bike size. I had already rode for the day so I just threw it up on the trainer outside before dark. Thats why I am in street clothes.
07-12-11 | 06:50 PM
#34
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07-12-11 | 06:54 PM
#36
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From: Venice, CA
Bikes: Bianchi Infinito, Bianchi Via Nirone, Bianchi Vigorelli
If you dont think saddle setback has no effect you are wrong....I will use myself as an example. I ride a 53.5 virtual top tube with a 135mm stem....normally I would be a 120mm stem, but I ride with a saddle setback of 25mm because I have a 32.75" inseam but I have short femurs relative to tib/fib.
That makes my position high and short since the relative distance of hip to crank arm spindle will not change...just the angle between my hips and the spindle..(lower and back or higher and forward)
Sitting about 25mm more forward than a person with the same build but longer femurs places my upper body that much farther forward and thats why I have a super long stem. Alternatively I could ride a 55cm with a 120mm stem. My measurements ideally put me at 66cm not 67cm but the saddle setback forces me just a little farther forward
That makes my position high and short since the relative distance of hip to crank arm spindle will not change...just the angle between my hips and the spindle..(lower and back or higher and forward)
Sitting about 25mm more forward than a person with the same build but longer femurs places my upper body that much farther forward and thats why I have a super long stem. Alternatively I could ride a 55cm with a 120mm stem. My measurements ideally put me at 66cm not 67cm but the saddle setback forces me just a little farther forward
07-12-11 | 07:02 PM
#37
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From: Venice, CA
Bikes: Bianchi Infinito, Bianchi Via Nirone, Bianchi Vigorelli
Your positions look pretty decent....I would raise the seat 1cm and move it forward 5mm-1cm. It hard to see the pedal axle but you look just a tad back....but nothing wrong just less aggressive compared to your bar drop.
Your stem looks fine, you could go 1cm longer or not, its a preference thing. Longer = more elongated position and slightly less "rounded" back.
Here is a secret a lot of roadies still dont get but I promise this works. Try to find a position that lets you breathe the deepest like yoga breaths through your gut....like inflating a basketball under your shirt. When you find that position I will bet you anything you want it looks like a perfect position for your current flexibility. Most sports come down to the breathe and in cycling finding the optimal breathing position while recruiting the most muscle in the stroke is what you're looking for.
Your stem looks fine, you could go 1cm longer or not, its a preference thing. Longer = more elongated position and slightly less "rounded" back.
Here is a secret a lot of roadies still dont get but I promise this works. Try to find a position that lets you breathe the deepest like yoga breaths through your gut....like inflating a basketball under your shirt. When you find that position I will bet you anything you want it looks like a perfect position for your current flexibility. Most sports come down to the breathe and in cycling finding the optimal breathing position while recruiting the most muscle in the stroke is what you're looking for.
07-12-11 | 07:15 PM
#38
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I was going to suggest dropping your seat a smidge to take some weight off your hands while you get used to riding that bike. Going a bit lower, say 5mm won't do your riding any harm, and if the pain in your hand keeps up you can tick that one off the list. Coming down a touch might make it easier for you to rotate your hips forward a little, taking some of the curve out of your back which can make things more comfortable on longer rides.
Remember that you will gain a bit of flexibility as you ride, but you're not there yet. Bike looks like it fits well, so that's not so much of a problem.
EDIT of course don't go so low with the saddle that you get knee pain, and try to change one thing at a time in small increments. You want to give your body time to adapt to each change, and it's easier to track the effect of the changes you make if they're isolated.
Remember that you will gain a bit of flexibility as you ride, but you're not there yet. Bike looks like it fits well, so that's not so much of a problem.
EDIT of course don't go so low with the saddle that you get knee pain, and try to change one thing at a time in small increments. You want to give your body time to adapt to each change, and it's easier to track the effect of the changes you make if they're isolated.
07-12-11 | 08:20 PM
#40
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From: Jonesboro AR
Bikes: Trek
Ok thanks alot guys. I really appreciate it. And it is more elbow pain than hand, I dont suffer from any numbness in my hands at all. Just that annoying tennis elbow like feeling after medium to long mileage that last the rest of the night. I thought the stem might be the culprit after reading about similiar pains from other riders. And so the general consensus is that I def would not benefit any from a shorter stem going on the pictures, and that if anything I could possibly go up to a 120mm stem to take out some of the back curve.
Also I will move the seat forward a bit to get a little more over the pedal axis. In the pics the seat is moved all the way back as far as it will go to give me the most breathing room in the drops with my forearms horizontal to ground so if I move it forward it might make me a little higher in the drops but I dont think that will matter that much will it?
Also I will move the seat forward a bit to get a little more over the pedal axis. In the pics the seat is moved all the way back as far as it will go to give me the most breathing room in the drops with my forearms horizontal to ground so if I move it forward it might make me a little higher in the drops but I dont think that will matter that much will it?
07-12-11 | 08:48 PM
#41
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From: Venice, CA
Bikes: Bianchi Infinito, Bianchi Via Nirone, Bianchi Vigorelli
Priority #1....position the engine...you!!..actually your hips in the right spot. Thats the first thing always...upper body is their just to balance out the engine and keep the air intake (your lungs)open and working to send that oxygen to your muscles.
So find where you feel the most power and comfort pedaling which looks for you like a tiny bit higher and come in 1cm at least. I say higher because when you move the saddle forward you need to make up for the distance to the pedals you just lost.
Once you can pedal sitting in the saddle then worry about the upper body. Until your hips are in their ideal spot you will never know where your upper body should be. But once you have it you should shoot for a relaxed upper body that allows for maximum breathing and doesnt focus the weight into any particular spot like hands neck or back, but instead spreads it out.
From your pics here is my total advice summarized:
1. Saddle moved 1 cm forward
2. Saddle moved 5mm-10mm up
3. Remove 1cm spacer from your stack to lower your bars. This will elongate your arms and allow you to straighten your back a little...if not get a 120mm stem and keep your current height.
So find where you feel the most power and comfort pedaling which looks for you like a tiny bit higher and come in 1cm at least. I say higher because when you move the saddle forward you need to make up for the distance to the pedals you just lost.
Once you can pedal sitting in the saddle then worry about the upper body. Until your hips are in their ideal spot you will never know where your upper body should be. But once you have it you should shoot for a relaxed upper body that allows for maximum breathing and doesnt focus the weight into any particular spot like hands neck or back, but instead spreads it out.
From your pics here is my total advice summarized:
1. Saddle moved 1 cm forward
2. Saddle moved 5mm-10mm up
3. Remove 1cm spacer from your stack to lower your bars. This will elongate your arms and allow you to straighten your back a little...if not get a 120mm stem and keep your current height.
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