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Most bikes/frames seem to be sold by matching the frame size to the height of the rider. I've recently bought a Vitus Nucleus, size M, based on falling bang in the middle of the height range for a medium size frame. The problem is it feels like the bars are too close.
I should say that I am 5ft 9" and have the arms of a gibbon, so now I'm thinking maybe a large would have been a better choice. After all the seat height can be adjusted, the reach can't.
Maybe I should have studied the dimensions more closely before purchasing.
You height gives you an idea but as you say leg length, torso length, arm length will mean that people of the same height are different. I have long legs and short torso so need a smaller frame fro my size.
Height is a rough cut for most bikes just gives you an idea if it's close. One of the bigger problems of buying online really as you can't see if you are close or not.
Two people of the same height can be very proportionately and bio mechanically different .
I'd say these two require two very differently sized bikes for sure yet are the same height and I say even then they will have different riding abilities :
Maybe I should have
studied the dimensions more closelyhad a test ride before purchasing.
No because you can bend your arms with relatively little effect upon how much power you can apply to the bike. But your torso length is fixed. And although you can bend your legs their working range for generating pump and pedal power is limited.
Leg length determines saddle height. Torso length is the main determinant of reach - but if your legs are longer you won’t need quite as much reach because your hips end up further back. Arms - well it depends on how you use them.
It is difficult to buy bikes that you can't test ride for whatever reason. Riding a lot of bikes to get a feel for what you like helps. These days I look at reach and effective top tube (or seat tube angle, which tells you basically the same thing). The reach I tend to "feel" when up on the pedals, the ett when I'm down in the saddle.
A lot if bikes don't quote a standover anymore because they believe you should buy based on stack and reach but I'd still like to know if I have bail room before catastrophic damage occurs.
Also sounds like you might be positive on the ape index.
This might help
https://www.competitivecyclist.com/Store/catalog/fitCalculatorBike.jsp
Seat posts go up and down with the use of a clamp.
Top tubes have no such adjustment mechanism.
“I’d say these two require two very differently sized bikes for sure yet are the same height and I say even then they will have different riding abilities :
Squats”
I’m long of leg and short of back and am battling to get my squats anywhere beyond bad. My deadlifts are pretty solid. You become very aware of how you’re put together when you start to try to move weight!
Chiefgrooveguru - you may find this interesting. Shame bike shops don't have a scaled down anatomically adjustable metal bike fit person for bike fitting MTB's to people.
“Chiefgrooveguru – you may find this interesting.”
Just got my first pair of heeled lifting shoes to try and improve my leverages when squatting - doesn’t help that my right ankle is messed up from an old MTB crash and has limited movement...
...
Leg length determines saddle height. Torso length is the main determinant of reach – but if your legs are longer you won’t need quite as much reach because your hips end up further back. Arms – well it depends on how you use them.
Which is why effective top tube is still a useful measurement.
“Which is why effective top tube is still a useful measurement.”
My point was that your hips are further back when standing, not sitting. ETT won’t tell you anything about that.
ETT is almost pointless as it’s usually quoted at useless heights with bikes whose seat angle is often slacker than quoted (due to forwards offset to clear the rear tyre).
My point was that your hips are further back when standing, not sitting. ETT won’t tell you anything about that.
Um, no comprende.
ETT is almost pointless as it’s usually quoted at useless heights with bikes whose seat angle is often slacker than quoted (due to forwards offset to clear the rear tyre).
Also other understanding. Can you expand a bit?
I'm only 67", but my "axle to seat surface" with size 10 feet is 34.5".... Some of these guides would have me on a large bike if I went with inside leg, whereas I really need a small in most cases as my torso is relatively short... You need to work out your inside leg:height ratio- I read somewhere it's on average 45% of your height. I'm 48/49%....then work out the ape index and you should know a bit more of if/where your dimensions deviate from the "norm"...
Depends largely on what you like and the style of riding as much as your dimensions.
I regularly switch between 26 inch jump bike with 425mm reach, and a 29 inch XL enduro bike with 485mm reach.
I've also been riding a size M 29er enduro bike with 430mm reach. It feels just as comfortable, but naturally it gets ridden in a different way.
shorter bike - more like a bmx
longer bike - more like a dh bike
The caveat is that my riding is more freeride/DH based. Ignore all of the above if you do lots of mileage sat down where sizing may be more important.
Have always been between sizes myself at 6’1” but with stumpy 31/32” inseam and loooong torso.
Have learned over the years that I much prefer lower and longer bikes (Cotic large pretty much nailed on for me), with at least 23” TT. Road bikes even trickier, I need a rarer 57cm sizes, as 58cm are usually too tall for comfort. I usually have to ride 56cm with a 120/130mm stem.
And inside leg.
It's better having a short seatube/low standover and one of the latest long dropper posts! So you can squash your COG right down when needed. If you get bucked the saddle (when fully lowered) is less likely to kick you up the arse and over the bars.
You can still use a longer stem to improve reach. Ridden bikes with up to 90 mm long stems and had no problems getting them down proper DH trails, round berms, switchbacks, over jumps and drops without flames burning me or a fiery death coming up short. The shortest stem I run at the moment is 45mm on my hardtail.
If you are only adding length by say 10-30mm on a 50mm stem, it won't radically alter the handling (you can also reduce bar width to compensate) unless the bike is already ridiculously short for your body size.