Kilroy1988 

Howdy,

So I just came across a 1930s Selbach catalog that gives an example for how a rider should reckon the fit of their bicycle, by stating that a 35" inseam would equal a 22" frame + 6 1/2" crank arms + 3 1/2" exposed seat post + 3" saddle height = 35". This assumes that a rider should have the equivalent of their inseam between the top of their saddle and the center of the pedal shaft.

I'd always wondered how riders of the mid-20th century managed to fit onto such small frames (22" was a standard max frame height for most British racing bikes in the 1930s, for example, and production bicycles rarely surpassed 23" until the 1960s). Upon checking I found that my ride height is actually 36.5" while my inseam is only 34.5". At first I wondered how this is even possible but there is probably some height made up for in the extension of the foot over the pedal, and of course with the body pressing against the saddle there is maximum extension in the leg...

So, I'm going to go lower the saddle on my 1951 New Hudson with pre-war frame angles two inches to account for the popular measurement of the day, and see how much difference it makes in the ride quality! I honestly already feel that my knees could use some more extension during much of my fast riding, so it will certainly be a curious experiment...

What's the difference between your standing inseam and the measurement on your bicycle(s)?

-Gregory

jamesdak 

Spoonrobot 

This is all over the place but you'll have to excuse me I've been reading old rivendell readers all day. Saddle height is .883 times inseam as the gospel has been written. 83.19cm*0.883=73.45cm, 73.45cm+17.25cm=90.7cm

M cycling inseam is 32.75" so my ride height is almost exactly 3 inches above my inseam. Foot height over pedal due to cleat/shoe thickness as well as overall foot length make up the difference I suppose.

Funnily enough my ride height is almost exactly 109% of my inseam as well - Dave Moulton's Blog - Dave Moulton's Bike Blog - Saddle Height

Also keep in mind the average British male height did not reach 5'9" until the 1950s.

Kilroy1988 

Interesting stuff. Where did the 17.25cm come from in your equation above? (Ah, I see now - you've included the crank arm length after the primary equation using the .883.)

The Selbach article specifically used a 35 inch inseam for their example, which is typical of a male standing about 6' or more in height. It was just an example but it also happens to be almost exactly my inseam... Though I usually prefer riding frames closer to 25" to avoid overexposed seat posts at the 36.5" ride height I've got.

Salamandrine 

This method is just another way of stating the old rule of thumb for saddle height that was used when I got into cycling. That ROT said that the saddle should be at the height where you can just touch the back of the pedal with your heel and your leg straight, when the pedal is at the bottom of the stroke and inline with the seat tube. It's important that your hips not rock. The slight offset of quill pedals in common use at the time would give essentially the same result as the above method. Most people still ride something close to this. There have been various trends one way or another over the decades, but if you look at very old bike racing pics, you'll see that for the most part extension is about the same, though it varies a bit between individuals.

If your inseam really is 2" less than your ride height, IMO your saddle is too high. By inseam here we are talking PBH, not pants inseam. Improperly measured PBH could easily throw all this off.

Kilroy1988 

According to Dave Moulton blog post linked above it makes perfect sense to have a saddle height longer than inseam - in fact, mine is lower than that 109% average (it would be roughly 3" more than my inseam). And I know how to measure actual inseam, thank you. I would never reference my pant size to assume the actual length of my body.

Salamandrine 

I think what's not making sense here, and I'm postulating I admit, is that the 30s Selbach Catalog is taking inseam to mean the point of your crotch sitting on the saddle to the end of you leg at the heel. IOW your inseam measure in cycling position. This is a different measure than standing inseam, but if you think about it, it makes sense. I don't think anyone rides with a ride height equal to their standing inseam, and that includes racers in the 30s. Mine is maybe 1 5/8" more, I forget exactly.

AFA that study in the Dave Moulton blog post, I read it for the first time in 1979. Adjusted my saddle to that height. Tried it out for a couple weeks. Got chewed out by my club's quasi coach, a cat 1 FWIW, and reduced the height back to 'normal', where it has remained to this day. Not many people actually adjusted their saddles to the methods encouraged by that study. It was somewhat provocative IIRC.

Kilroy1988 

If so then my true reach is apparently closer to 36.5", because I can just graze the back of my pedal with my heel based on the way you described doing so above. My relaxed standing inseam (which fluctuates throughout the day and I think has been a max of around 35" without trying to squeeze anything too hard) would be less. The Selbach catalog states a frame measurement "can be calculated on leg reach or inside leg measurement," which is in fact rather vague if I can apparently find measurements fluctuating almost two inches just for myself!

I also look at a lot of period photos of British riders and have noticed that their knees never look very extended, even when the pedals are apparently almost straight out from the saddle position. This does make my wonder whether their standard position would have been somewhere in between what we're considering here. Hmm...

-Gregory

Take these for example, from the Classic Lightweights photo gallery.

Salamandrine 

I kind of think it varied a lot through cycling history. I never did lower my saddle quite as much as the above mentioned coach advised. He was the older generation and I wanted to do it the new way. What I found is that lower saddles make it easier to spin. Higher saddles give a bit more torque when seated. In the days of one speed freewheels or fixed gears on road bikes, likely with about a 70 inch gear, it may have made sense to go with a pretty low saddle. You'd need to be spinning quite fast on the flats, and in the hills it is going to be all out of the saddle anyway, so seat height is irrelevant.


Yeah some vintage pics show 'interesting' position. They can be all over. Even so, they seem to be not to far off from today, for the most part. For contrast, here's a picture from Dave Moulton's blog circa 1937 showing a fairly high saddle position:


PS, can someone tell me what those brakes are?

RobbieTunes

Me, I just want their hair.

Kilroy1988 

Salamandrine, if either of the photos I linked were views from the same angle as the shot you show, it could probably look similar. Only side shots are truly helpful in this case.

Resilion cantilevers. Very popular on '30s British road and touring bikes. Here's a detail shot from a c. 1931 BSA...

ryansu

According to bike fit I am built wrong, my legs are too short for my body as a result of having a long torso. I only have a 30 inch inseam but I ride 58 cm frames for vintage bikes, that means the stand over is pretty much non existent but the longer tt accommodates my torso, also I end up showing less than a fistful of seatpost as wisdom suggests.

I end up ignoring standard fit advice and going with what is comfortable YMMV

Last ride 76 

[QUOTE=ryansu;20514573]According to bike fit I am built wrong, my legs are too short for my body as a result of having a long torso. I only have a 30 inch inseam but I ride 58 cm frames for vintage bikes, that means the stand over is pretty much non existent but the longer tt accommodates my torso, also I end up showing less than a fistful of seatpost as wisdom suggests.

I end up ignoring standard fit advice and going with what is comfortable YMMV [/QUOTE


If you don't mind my asking, how tall are you overall and how long a stem do you use on this set-up? What shirt sleeve
length fits you properly? 34?


I agree with going with what is comfortable, with the caveat that sometimes it takes a while to become comfortable with a more efficient position.
(One of these days I would love to do a bike "fitting" for the different purpose bikes I have. I don't think my basic road position wuold change much, but I'm still curious.
Cheers, Eric

I'm finding that saddle type/brand seems to make the most difference, even after saddle location, tilt etc is made as similar as possible. I am still most comfortable and productive on a semi-grippy unicanitor / concor type. Smooth leather or synthetics, dont work for me so far.

3speedslow

John E

You are supporting my argument that top tube length can be even more important than seat tube length in determining one's "ideal" frame size. This is also one argument for custom built-to-measure frames, or at least shopping around among various brands and nationalities of bicycles, to find what fits YOU best. Women-specific road frames, such as from Terry Cycles, tend to be a bit shorter in the top tube than their generic or gent-specific models. It sounds as though you need the opposite, something like my Peugeot UO-8. Even though it is only a 21" frame, and my ideal size is 55cm C-T (Bianchi and both Capos), it is long in the top tube and serves me well, with a fair bit of seat post showing.

Charles Wahl

My standing pubic bone height (Dave Moulton's "inside leg") is 89 cm, and I seem to be most comfortable when saddle is 94 cm above the top of pedal (105.5%), measured along seatpost and seat tube, with crank so aligned. Any shorter, and I feel that my knees are a bit cramped (not extended enough) at the bottom of stroke. A cm higher and I feel that my hips are starting to rock. I believe that this was St Sheldon's method to find your saddle height for a bike: keep raising your saddle in 6 mm increments until you feel that your hips are rocking, then go back to the setting just previous -- done.


My inseam (trousers), OTOH, is 32", or 81 cm.

The Golden Boy 

I've been in the process of getting a new, modern steel bike.

I seriously didn't know until a couple of weeks ago that I can't stand over my bikes. Not a one of them.

I wear 30 inch trousers- and it occurred to me that I probably don't wear shorter trousers because that's how short they usually go in the mens' section and I don't want to shop in the boys' section. Plus, I prefer my waistline to be a bit higher- because shirts are always short on me.

So I normally ride 21" bikes, and I've really found 2 bikes that feel like home to me... I kind of thought it's because I know how cool they are- but really with a 55 and 56.1 top tube- it makes sense they fit me better with a longer torso.

Reynolds 

83cm inseam, 74.5cm saddle/BB.

ryansu

[QUOTE=Last ride 76;20514588]Once upon a time I was 5' 11 3/4 " I am probably closer to 5' 11 these days. A 34 sleeve would be ideal but I usually have to settle for a 33 or a 35. Stem length tends to vary by bike but usually in the 80 to 100 mm range, it would be longer if I tried to ride a 56cm frame.

Classtime 

RobbieTunes

According to the 1987 Bicycling Buyer's Guide, I should be on a 52 or 53cm.

I think the 54's and 56's look better, so I ride them. Last time I measured for a builder, he recommended a Medium, which I think was 54 or so....

JaccoW

I have a size 64 bike with about 16/20cm of seatpost extension. I'll measure my legs tonight but I usually wear 36inch length trousers.

mstateglfr 

PBH is 95 or 96. I think 95?
Saddle height on all my bikes is 84ish cm.

Its funny- i only set up 2 bikes by measuring. All my other road bikes have been set by feel and they are all within 1cm of each other.

There is a need to take into account saddle style and crank length too. I have some 170mm crank arms and some 175mm arms. Additionally, the amount that a saddle flexes needs to be considered.
A bike with 175mm crank arms will have a slightly lower saddle height vs an identical geometry bike with 170mm crank arms.
A bike with a leather B17 saddle will have a slightly higher saddle height vs an identical geometry bike with a stiffer saddle.

That sort of thing.
Salamandrine described the process I use- adjust the height until my leg is extended with the arm is down and my heel is touching the pedal. That then means when the ball of my foot(cleat) is on the pedal there is a slight bend to my leg. Perfect every time.

belacqua

I measured my bikes for the first time and they were all between 76 and 78cm saddle-to-BB center. PBH is 91. With my 175 cranks that puts me at about 94 or 95 cm.

This is really thought-provoking. I have always fit by a combination of feel and heel-graze test. Should I try raising my saddles 1.5cm?

thinktubes