Seat Tube Angle - What do you know?
- Thread starter whittod
- Start date
Quantitatively, it would not seem like a lot, but if you are taller (let my arbitrarily say above 6'1"), you would probably want the frame with a 72.5º seat tube angle IF all other things were equal between two frames which you mght be considering.whittod said:
Heck, if I were having a custom frame made, I would now spec a 72º or 72.5º angle, and I'm only 5'9", BECAUSE I've completely rejected the religion which embraces the KOPS frame fit (hence, my failure to echo the chant that riders benefit from a professional frame fit).
Let's say that you haven't eschewed the KOPS frame fit theory, yet ...
The slacker seat tube angle will PROBABLY allow YOU (as a taller rider) to clamp your saddle in something other than the exteme aft-position and thus provide more fore-aft adjustment without resorting to a different seatpost with more setback than an off-the-rack bike will probably come with.
BTW. In America, the steeper seat tube angles appear to have come into vogue on non-custom frames in the late 70s when the road bike market more definitively separated between sportier (aka "racing") & touring frames -- the shorter the chainstay, the rougher the ride.
That's the short explanation.
Man, you are asking for a heap of information!whittod said:
Everything on a bicycle works together. The more vertical seat tube angle (72.5) might mean the chain stays are shorter. Riders with more drop to their handlebars tend to prefer the more vertical angle because they rotate their torso's around their hips.
Trying to divorce one dimension from the reat of the bike probably isn't the right thing to do.
You're right. I wasn't paying that close attention because it's really a side issue that doesn't matter. My point about not being able to divorce one dimension from the whole bike design is still valid.alfeng said:
I have noticed many manufactures adopt the steeper seat angles and notice alot of locals using all of there seat rails or going with a set back seat post to get the correct rider position, which seems to indicate the wrong geometery...and thats before we even talk about the top tube lenght, stem lenght and front center.
Many years ago I was riding a Guerciotti that was much more relaxed...as you could feel the difference when pushing the big gears...with your power coming from your glut's vs quads...as most of the euro brands are all 73 degree seat angles these days..so maybe custom is the way to go.
I wonder if the pro's are riding custom geometery vs what there selling to the general public due due the US style of racing ....ie criteriums vs road racing?
Many years ago I was riding a Guerciotti that was much more relaxed...as you could feel the difference when pushing the big gears...with your power coming from your glut's vs quads...as most of the euro brands are all 73 degree seat angles these days..so maybe custom is the way to go.
I wonder if the pro's are riding custom geometery vs what there selling to the general public due due the US style of racing ....ie criteriums vs road racing?
I always preferred my crit bikes more vertical and my 'all day' bikes (racing and training) to be less vertical.
1/2° of angle amounts to about .7cm (or .275") in 80cm. that's not very much given the amount of adjustment in the saddle rails/seatpost clamp. Most folks move around on the saddle a lot more than that.
1/2° of angle amounts to about .7cm (or .275") in 80cm. that's not very much given the amount of adjustment in the saddle rails/seatpost clamp. Most folks move around on the saddle a lot more than that.
This might be abit off topic...however I assume the reason folks use a setback seat post it to get the correct position which is the correct rider geometry..right? Otherwise why would they use it?
I guess what I'm saying it there is a rule of thumb when setting up the correct riding position vs pushing the seat back and adjusting the stem lenght to fit the rider to a predetermined geometery as it applies to road racing. Thanks for the discussion.
I guess what I'm saying it there is a rule of thumb when setting up the correct riding position vs pushing the seat back and adjusting the stem lenght to fit the rider to a predetermined geometery as it applies to road racing. Thanks for the discussion.
A rider's butt has to be in a certain position (range, actually) based upon femur and foot length.
A steep, short-coupled frame with a curved seat tube used to be one way to accomplish this. A seatpost with offset built into it is just another means of allowing the rider to assume a more rearward pedalling position.
For some of body types and for some types of riding this is desireable. For other body types or types/styles of riding/racing it is not.
A steep, short-coupled frame with a curved seat tube used to be one way to accomplish this. A seatpost with offset built into it is just another means of allowing the rider to assume a more rearward pedalling position.
For some of body types and for some types of riding this is desireable. For other body types or types/styles of riding/racing it is not.
CAMPYBOB said:
Yup. I'm of the long-legged, shorter torso sect, so I don't know that I could find an off the shelf frame that would let me use a straight post and have the proper position. As it is, with 25mm of offset in der seatpost, my saddle is pretty much centered in the clamp....
I don't know about that. As I recall pretty much all seatposts used to be set back 15 - 25 mm. I seem to recall seeing no setback posts first cropping up on mountain bikes.whittod said:
Back in the day, the standard advice to racers for setting their bakes up "euro style" was to hike the seatpost and slam the saddle all the way back on the rails, like Lemond used to.
