Cockpit fit

simonp123

Whilst I am off from riding recovering from a carpal tunnel release operation I though I would look at the cockpit setup of my bike, which I have been meaning to do for ages.
I am a little confused about saddle for and aft positioning though. I have seen 2 rough check methods. The first says to drop a plumb-line from the saddle nose and it should fall in line or a little behind (no more than a couple of inches) the bottom bracket. The second says to drop a plumbline from the middle of the saddle and this should intersect the chainstay equidistant between the BB and the rear wheel axle. Well, I did both of these, with the first the nose of my saddle is some way over 2 inches behind the BB, but the second method comes out as smack on. I'm a bit confused really.

I also did the rough guide to stem length & handlebar position by putting my forearm between the nose of the saddle and the stem. I was surprised to find my middle finger going some way past the middle of the stem reach. I was thinking about dropping from a 90mm (15 degree rise) stem to a 70mm one for sharper handling, but I don't think I can based on that measurement. The bike is based on a 2006 Stumpjumper FSR 120 frame.

cooldad

Forget all that, adjust everything so it feels comfortable for you.
Might work on a road bike where you are effectively in the same position all the time but means nothing on an MTB where you move around a lot.

mkf

there all just guidelines, you know how your bike handles now so make your changes go ride and see if its better.
keep if its better go back if its crap.

simonp123

To be honest the setup is a bit thrown together as the stem is the standard one from my old Kona Blast, and I changed the seat and post a few weeks back (gone from a straight to a small layback in the post), and just bunged the seat on and got it level before a ride and haven't got round to adjusting it yet. All I do know is the seating arrangement is better than before.

Actually the info for the seat setup was from articles about mountain bikes :roll:

Looking at some photos of older Stumpjumpjers like mine, the stock seating looks to be with the nose some way back behind the BB anyway.

cooldad

Might have been more relevant when MTB was a lot of fireroad type riding and a lot was done sitting down, but I seem to be standing for most of the fun bits.

The Rookie

How can a saddle positioning (using the nose) be right when you have different length saddles? Blatant 'wrong' there.

Put it where it feels right, I run my saddle right back as
1/ I'm a strange shape, run a medium frame and need to lengthen the cockpit a bit
2/ I can sit forward on the saddle if I need to anyway!

Simon

larryb

simonp123 wrote:

To be honest the setup is a bit thrown together as the stem is the standard one from my old Kona Blast, and I changed the seat and post a few weeks back (gone from a straight to a small layback in the post), and just bunged the seat on and got it level before a ride and haven't got round to adjusting it yet. All I do know is the seating arrangement is better than before.

Actually the info for the seat setup was from articles about mountain bikes :roll:

Looking at some photos of older Stumpjumpjers like mine, the stock seating looks to be with the nose some way back behind the BB anyway.

Article taken from Cycling plus 1981's feature 'A Bike that can ride canal paths and is not a bmx'

Neal_

I've found this article very useful for fitting a bike - How to Fit a Bicycle

cooldad

Neal_ wrote:

I've found this article very useful for fitting a bike - How to Fit a Bicycle

99.9% aimed at road bikes. 0.1% added at some point (ATB - presumably added quite a while back)

timpop

Your saddle theory doesn't fit in my mind as mountain bike angles are all different. It sounds like something for a more upright bike.

What works for me is similar as you described though. I try and line up my forward knee to the pedal (at plumb line) when the cranks are in a horizontal position. This gives me a good position for pedal power (and less knee torque) while seated. But that is just the beginning to finding the best set-up.

You could get confused with all the measuring but in the end it's just about what works best for you. Try a few things out, different positions and angles and even change it during a ride if it feels odd.

I hope your recovery is swift.

Neal_

cooldad wrote:

Neal_ wrote:

I've found this article very useful for fitting a bike - How to Fit a Bicycle

99.9% aimed at road bikes. 0.1% added at some point (ATB - presumably added quite a while back)

True, I should have added that I only used the seat height and fore/aft position techniques. Moving my saddle back a little bit reduced the pressure on my hands which was more comfortable on long rides, also I liked the idea of setting the position up to what is comfortable for you and your riding rather than messing about with plumb lines.

supersonic

Have a read of this:

http://www.bikeradar.com/fitness/articl ... ike-26027/