General Cycling Discussion - Question on seat height adjustment

Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.




tpelle
03-06-11, 11:18 AM
I'm getting a new bike this week from (Gasp!) Bikes Direct. It's a steel frame road bike that I am going to use as a weekend recreational bike and possibly a commuter.

http://www.bikesdirect.com/products/motobecane/mirage_xi_steel.htm

The situation is that I'm on a temporary (six to nine month) work assignment on the west coast, but I will be flying back home for a long weekend every two weeks or so. I'm having the Bikes Direct bike shipped to my apartment out west, and this way I'll have a bike to ride in both places - besides, I didn't want to risk my Surly getting banged up or going AWOL if I boxed it up and shipped it.

My present bicycle is a Surly Long Haul Trucker. Out of curiosity, more than anything else (and so I'd have a measurement to start with on the BD bike), I measured my seat height by aligning one of the crank arms with the seat tube, then measuring from the pedal to the top of the seat (a Brooks B17). I measured it at 38-1/2".

BTW the Surly was professionally fitted and set up by my LBS when I bought it, and is quite comfortable to ride.

My stand over clearance is 36".

I was a little surprised that the seat height is 2-1/2" higher than my stand over height. Does this sound right?

I guess that this reflects that I'm pushing on the pedal with the front of my foot, not the heel, huh?


10 Wheels
03-06-11, 11:23 AM
Bad measurement.

Measure from the center of the crank to the top center of the seat.

tpelle
03-06-11, 11:58 AM
bad measurement.

Measure from the center of the crank to the top center of the seat.

ok. 32-3/4".


fietsbob
03-06-11, 12:02 PM
You should have extra space over the top tube straddling the bike .

.. after all it hurts when you have to bail and you don't.

tpelle
03-06-11, 12:10 PM
You should have extra space over the top tube straddling the bike .

.. after all it hurts when you have to bail and you don't.

Well, of course. But my question is really about the height of the seat relative to the pedal, so that one's leg extends to the right extent on the pedal stroke. I figure that this measurement should be from the top of the seat to the surface of the pedal when it is farthest away, which would be when the crank arm is in line with the seat tube. Just wondering if the measurements that I got on my LHT looked to be in an appropriate range considering my stand over height?

skijor
03-06-11, 12:13 PM
Yup, a little (no more than an inch) clearance when standing over the top tube. Plus a slight bend in the knee when you're at the bottom of the stroke. And the pedal spindle should be about in the center of the forefoot. These are good starting points.

achoo
03-06-11, 01:18 PM
Yup, a little (no more than an inch) clearance when standing over the top tube. Plus a slight bend in the knee when you're at the bottom of the stroke. And the pedal spindle should be about in the center of the forefoot. These are good starting points.
That can't be emphasized enough.

Don't get all wrapped up in "a plumb bob from you knee should ....", err, stuff. Recumbent riders don't spontaneously explode from having - GASP - the crankset out in front of their body and - GASP - above their hips (for some recumbent bikes).

IMO the most important thing is to first get the right DISTANCE between the saddle and the crankset. Then modify the fore/aft position of the saddle in order to get your weight balanced the way you want between your saddle and bars - without forgetting how that effects the distance from the cranks. Too much weight on your hands? Move the saddle back.

Then set the saddle tilt so you don't feel like your sliding off the front or back.

Then setup your bars to get a comfortable reach.

wahoonc
03-06-11, 02:43 PM
I use the seat to pedal measurement as a starting point and adjust from there. I actually keep a log of the various dimensions of the bikes I ride regularly and they are all within a 1/4"-1/2" of each other, they very in style and geometry so that is not surprising.

Aaron :)