Bike Forums - Sore Lower Back

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Thoughts on my son's bike fit ?? He gets a sore lower back after about 10 miles.
15 years old, 5' 11", 56 cm old Cannondale
Only 10 rides or so on the road bike. Casual hybrid rides before this.
I think he needs to rotate his hips forward and flatten out his back a bit.

http://i845.photobucket.com/albums/a...11_1711311.jpg

Raise the saddle a bit.

Quote:

Originally Posted by Homebrew01 (Post 18235384)

I think he needs to rotate his hips forward and flatten out his back a bit.

I think this is probably the issue. He is bending his back to reach the bar rather than rotating his pelvis. It looks like he wants to sit straight up on the bike from the hips down.

Old geometry needs a different setup and flexibility versus newer. Below is Merckx. This was the best pic I could find with him on the hoods. Note how far back he sits and how much lower the brake hood position is versus late model bikes.

http://i170.photobucket.com/albums/u...on-cyclist.jpg

I agree that your son has to rotate his pelvis but he may lack the flexibility to do so. More than likely the reason his back is sore is that a rounded back position reduces / eliminates the glutes and makes power production quad centric. Once the glutes are eliminated, the back muscles work a lot harder to counter the forces from the quads. And the back muscles are designed to keep the back stable and erect versus countering hundreds of pedals strokes.

I think the fix is a smaller old school bike or raise the seat and move it forward and put in a smaller stem and raise the bars. Old school stuff as I remember it does not have a lot of flexibility to change effective top tube length.

Have your son try to visualize a very light touch on the handlebar and to squeeze his shoulder blades together. In other words, try to raise his chest. This will cause his hips to rotate - hopefully.

I think Hermes may be right. It is only one photo but is appears the saddle may be too far back. Once the saddle is further forward, the torso will be automatically more upright. At that point the length of the stem can be evaluated. It is really best to have a range of photos with the pedal at different positions.

He looks too far back. I've found that too much reach, or having the saddle too high OR low can cause lower back soreness. It's something I always dread about changing up the fit on my bike(s). Rotating your hips is going to be hard without clipless pedals

I can't tell from the pic... but a wild guess would be the saddle is tilted back BMX style. Level, and raise the saddle.

Here's the bike by itself. Saddle is pretty far forward already.

http://i845.photobucket.com/albums/a...17_1755311.jpg

The saddle looks forward, but that isn't necessarily wrong. I wonder if his drive-side leg shows that he is still too far back.

I don't think he's too far back at all. He just needs to rotate his pelvis, like you say:
http://www.bikeforums.net/road-cycli...discovery.html

More good position photos- you can ignore the hand pain part, just look at the photos:
http://www.bikeforums.net/road-cycli...l#post12953035

IME a good position should have elbows just clearing knees when on the hoods, forearms horizontal.

A video:
https://www.youtube.com/watch?v=z04uoO7U_SA
You can ignore the pedaling advice and just look at her position.

One can also get back pain just from having a weak back. However, cycling is perhaps the best back exercise ever, so if position is correct, more cycling = less pain.