pavement_nyc

So I think everyones seen this chart:
https://bicycling.about.com/od/howtor...ike_sizing.htm
I'm pretty sure there's an error/typo on this chart: the inseam for 6'2"-6'5" should be 33.5-35, if you look at the pattern they are using.

Anyways, I'm making a website, a used bike marketplace, and I made my own chart so that bike noobs can just enter their height, inseam, and preferred seat height, and be matched to the seller input of frame size. On the chart, each inseam has a max and min frame size which are narrowed down further by preferred seat height (1-low,2,3,4,5-high).



If you look at the example on the right for someone 6'0," the range will be narrowed when the buyer enters their preferred seat height:

1- Low, feet touch ground while seated
2- Low-Mid
3- Middle, toes can touch ground
4- Mid-High, toes can barely graze the ground
5- High, fully extend leg while pedaling

Anyone here on the forums will surely be a 4 or 5, yes I know it's sad but most beginners that I've sold bikes to want a low seat, even though I always tell them they should raise it.

So my question is, is this chart accurate? It is for me, I'm 6'0 which gives me a range of 56-61 being that I need to almost fully extend my legs while pedaling. The idea is that with a 56 I could have my seat raised high and with a 61 relatively lower, with 58 or 59 being ideal. Users will have the option to narrow down frame size as narrow as they want, but I want beginners to be able to just enter their height and see results (pictures of matching bikes).

loneviking61

Well, it's not accurate for me. I'm 5'11" with a 29 inch inseam, and ride with the seat at position4. According to the chart, with a 29 inch inseam, I should be 5'6" and on a 45 cm frame, which I'm pretty sure is wrong as at the LBS I usually fit a 52 cm frame.

pavement_nyc

First of all, you've read the chart wrong. At 5'6" / 29 inseam and position 4 my chart gives you a range of 48.5-53.5.

Secondly, you have a freakishly large torso

Velo Dog

Works pretty well for me at 6'4". You nailed my inseam, and while I don't believe for a second that I could ride a 58, I'm comfortable on my 64 and 65cm bikes.

loneviking61

your directions for adjusting size based on ride position still don't make sense..

And yes, I have a large torso as do a lot of Clydes. I guess we are just S.O.L. when it comes to using your site?

Spoonrobot 

That is a very poor chart. It's based on seat tube length, which is a non-starter for sizing. It's also confusing because height doesn't need to be on there if you're going to have it correspond directly to inseam.

e.g. my height is 5'8.75" but my inseam is 32.75" which correlates with an inseam of someone between 6'1" and 6'2".

The fit calculator is better since bike sizing cannot be distilled down to one measurement.

https://www.competitivecyclist.com/za...&SITE.CODE=RDB

I would hold off on attempting to disseminate any information until you know quite a bit more about the subject matter.

fietsbob

leaves out women entirely,, by locking inseam and height together..

maybe replicants can be standardized.. ('Blade Runner' fans)
human beings are not made to a standard dimension proportion..


going to shops and test riding bikes is a hard thing to bypass..

bobotech

I am 5'11" with a 29" inseam. The chart shows me being 5'6" and that is way off for me.

Machka 

Firstly, +1

I'm 5'6" with a 31" inseam.

According to the chart, I should be 5'10" and riding a frame as large as 58.5". Well, I can tell you right now, I have ridden bicycles that large, and they don't work for me.


Secondly, you should never ride with your leg fully extended while pedalling. There should always be a slight bend in the knee. If you ride with your leg fully extended, you are asking for achilles tendon injuries, and knee problems.


Thirdly, I hope those max/min frame size measurements aren't to the top of the saddle ... I hope they don't include seat height ... because that's just not how you measure a bicycle frame.



You mentioned in another thread that you sold bicycles ... do you have a shop in New York?

Machka 

Maybe this might help. I suggested it in the other thread, but perhaps you didn't bother to find it ...

These are many of the things that go into measuring a bicycle.

https://www.parktool.com/blog/repair-...stioning-chart