claulo

Good afternoon, I have a question regarding the size of my frame. Im 30 years old, and I cycle regularly, mainly in the City.
I currently have a Merida O. nine disc carbon frame, rim 26 size 16. My height is 1.70, and the height of the crotch is 78.5 cm. When I pedal uphill, my quads hurt when I push hard. It should be noted that I currently have an 11/34 pinion, and a 46 crankset. My question is this: Is the pain in the front knee and quadriceps the product of the supposed smallness of the frame? If that's the case, are there ways to fix this without buying a new frame? Thank you very much.
Postscript: According to Mérida's specifications, the frame size 16 corresponds to my height.

oldbobcat

There are numerous videos on YouTube on basic bike frame sizing and fitting. My suggestion is to try to set up your bike according to their guidelines, starting with saddle height and setback. If you cannot get the handlebar in a decent position relative to the saddle and cranks, then maybe the bike doesn't fit. Or maybe you just need a different handlebar and stem. The bike might be a little small, but I wouldn't rush out and buy a new one without working out your options and technique on this one.

Personally, my quads hurt when I was starting out. That was mostly from pile-driving on the pedals--pushing straight down in a large gear instead of gearing down, using a quicker cadence, and applying force that follows the arc of the cranks.

Carbonfiberboy 

My guess is that the bike's fine but you are using too large a gear. Try using a smaller gear and spinning the pedals faster - also known a using a higher cadence. This takes some getting used to but it's worth it. Ideally, you want to spin the pedals fast enough so that on a climb, you run out of air at about the same time you run out of legs.

Iride01 

It feels stupid till you get use to it, but when you are riding a bike you should not have to use any force to pedal.

Except maybe for really hard fast accelerations and for times you are climbing a hill and you don't have a lower gear ratio remaining to shift into.

You might check that your saddle is at the proper height. Maybe measure from the BB center to the top of the saddle where your sit bones touch and let us know that measurement. Though my preference is from the pedal when furthest away to the same place on the saddle.

claulo

I checked the height of the seat, and indeed it is a little low, very little (67.5 cm, it should be at 68.5). I corrected it, I'll try tomorrow. The bicycle has never made me uncomfortable, I don't feel it small. I think I am at the limit, in relation to the measures proposed by Merida.
Maybe its the gear, I dont know..

cyclezen

fitting a mountain bike is diffferent from road. And it also depends on kind of 'riding' one does.
But pain in the front of the knee and with over-engagement of the Quad usually comes from too low a seat.
And usually seat setback combined with seat height becomes a relational thing, but the more vertical seattube/post angles puts more emphasis on getting a good seat height for the gears you ride (and terrain).
Work on getting the seat height to a place that reduces the knee and quad pain.
If you're running typical mtb tires - slightly to more deeply lugged, you're not going into cadence ranges which might commonly be used for 'road' bike cycling. But if you can;t be in a gear that you can hold a consistent cadence, then use the next lower gear or until you can keep the cadence up and steady.
MTB fit can vary quite a bit, depending on the terrain you're riding - a lot depends on what position/posture your bike is providing in the current setup...
not something to cover in a couple paragraphs...
MTB Frame size - could fit in a wide range, I could ride a Sm thru Xl, if I could find a seatpost long enough to set my seat height in the smaller sizes... LOL! some riders do fine on small frames and like the quickness in technical terrain. Others like the feel of long and low. and that will also vary by wheel size. Frame size is likely not causing your issues.
work on the seat height until the knee and quad pain reduces and maybe becomes commensurate with the riding effort.
Ride On
Yuri

79pmooney

1 cm change in seat height is a lot. If the new height is right, no wonder you were having issues. The seat height guide I like is the heel test. Park the bike next to a wall. Get on it and sit upright and in line with the bike. (So you look down right through the tubes.) Rotate one pedal down until in line with the seat tube. Put your heel on the pedal spindle. Adjust seat height until you hit the magic spot where you can both bend your knee and straighten it without moving your hips at all.

Now, this is a guide, not an answer. The variable you need to find is what heel to wear for the test. We are not all alike. I like my seats on the low side and I do the test in my socks. Others use road riding shoes with no heels or house slippers. Others more substantial heels. Both preferred knee bend and your natural foot position (heel level, up or down) play into this. Don't change to fit this test. If I were starting this test from scratch, I might set the seat wearing road shoes, then go ride the bike and observe. Ask experienced riders for their opinion. Note how I feel after rides. Adjust (now, 2mm is a lot.) Observe some more. When you've got it, go back and do the test again but this time, don't move the seat. You are looking for the shoes. Once you've found the shoes with the right heels, you can dial in any bike very fast.