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Difference between 73 and 74 degree seat tube angle(17 posts)

Difference between 73 and 74 degree seat tube anglecycleforever
Aug 22, 2002 11:26 AM
I've decided to buy a new bike at the end of year (year end closeouts) and already have two picked out the Litespeed Siena and Tuscany. Both bikes fit, but one of the differences between the two is the Siena has a 73 degree seat tube angle and Tuscany has a 74 degree. Is this a big deal, personal preferences, or riding style. The bike I have now has a 74 degree angle. Is the any advantages or disadvantages between to the two angles?
dependsDougSloan
Aug 22, 2002 11:47 AM
First, I doubt you'd ever know the difference if you weren't told.

The 73 will put your butt a little rearward with respect to the crank compared to a 74. If you had a long thigh bone compared to the rest of you, supposedly this is better.

Of course, you can accomplish essentially the same thing with saddle location on the seatpost, or the amount of setback in the seatpost. If you wanted the 73 to emulate a 74, you'd just move the saddle forward; however, then you effectively shorten the top tube, if they were equal lengths on the two bikes. Of course, you could then lengthen the stem to make up for it...

Some people make a big deal out of this stuff. To me, it doesn't matter a whole lot. If I feel comfortable and efficient, I don't worry. If your 74 is ok for you, then why change?

On the other hand, sometimes there can be significant reasons for a change. For example, if you want to spend lots of time on aerobars, the 74 would open the hip angle a little bit, giving you more room for your legs to move and make breathing a bit easier when down low.

Doug
you're giving reasons why it *is* importantET
Aug 22, 2002 2:09 PM
I personally think that the theory given by a few bike companies that adopting oneself to a given seat tube angle (STA), not to mention being the better for it, is mostly hogwash. One will for the most part adjust the seat to revert to his "natural" position. If one's natural position would, for a given (ideal) setback, put him center-of-rails for a particular STA, that is a better fit and a better choice if the top tube is appropriate than another.

The rule of thumb is that for each .5 degrees off of ideal STA, one must move the seat around .5-.65 cm (use the upper number for bigger frame sizes) in the opposite direction. So if someone is meant for a 73.5 STA but is riding a 72.5, he'll have to move the seat forward about 1.2 cm, putting him sort of close to the forward end of the +/- 2 cm rail and effectively shortening the top tube. Where's Anvil to tell us how some riders will feel the off-center difference and that it affects performance? (Of course, Lance and Co. proved that perfect fit isn't that important if you're riding an OCLV and/or Lance is on your team :-)). I do agree that being off .5 degrees or less is no big deal; in that case, just get the bike you want and make adjustments.
Two more dependenciesKerry
Aug 22, 2002 4:41 PM
STA is important if you can't move the saddle far enough (forward or back) to get the right relationship to the BB. If the 74 doesn't allow you to slide the saddle back far enough, it's a problem. STA also has some influence on the transmission of road shock; everything else equal, a steeper STA will send more of a jolt to your body from road bumps. Not a big effect, but it is real. If you can get the proper fit with either frame, then consider other factors.
exactlybianchi boy
Aug 22, 2002 6:43 PM
I have only found a few saddles I can use on my Gios with its steep(74) seat angle. Most saddles I just can't far enough back to get the proper knee-over-pedal position. Fortunately I found a saddle with long rails, after much experimentation, and I've got a good fit now. Other than the saddle issue, however, the 74 angle doesn't bother me.
My takeNessism
Aug 22, 2002 12:20 PM
In my opinion, the seat angle difference is important. I like a slack seat angle (72.5 degrees) and can not get a proper position behind the crank when using a 74 degree seat tube angle frame.

The important thing it to first position your body behind the crank and secondly pick the stem/bar combo that gives the proper reach to the bars.

What seat angle it correct for you? Only you can determine this. I would say that 1 degree is no big deal and can be adjusted out at the seat rails. More than this and you should look for a frame with a better fit.

Ed
a few other things that matter even more...elviento
Aug 22, 2002 12:31 PM
1. seatpost clamp design. Easily 3cm difference between a Look Ergo post and a Thomson Elite. Some seatposts can be flipped backwards, which gives you more forward saddle position.

2. Saddle rail design, the straight section of the rails on some saddles are long, allowing you to slide the saddle backwards, easily 1cm+ difference.

3. The crank length and the cleat position on your shoes. More forward cleats effectively slacken the seattube angle. easily 1cm difference.

Now you are looking at a lot of leeway there, so I say get whatever frame you like, it's always possible to get your desired position.
Makes me appreciate my LBS even more...MXL02
Aug 22, 2002 12:43 PM
all this talk and my own personal experience about getting dialed into a frame makes me appreciate letting a local guy build it up for me. Yeah, you may be able to save some money buying the components somewhere else, but there is nothing like sitting on a trainer and trying out different stems, seatposts, saddles, and their respective positions to get the fit and feel you want and need. Ordering a built up bike from Colorado Cycles or Wrench Science just can't be the same, and once you get it, you own it and all the wrong fitting components someone in a different city thought you should have. There is so much variability out there, I think it pays to do the fitting in the flesh.
While that's a very good point,elviento
Aug 22, 2002 1:17 PM
you have to recognize that sitting on a bike for 30 minutes is very different from sitting on it for 30 hours. I found that my feel for a lot of things (bike's road feel, saddle comfort, bike setup, geometries, body position, etc.) comes only after spending significant time in the saddle. Also one's flexibility and other physical needs and preferences change over time/season, so there is no quick fix with formulas and shop fitting.

I do agree that having an experienced mechanic check your fit is a good starting point.
Yes, butMXL02
Aug 22, 2002 3:34 PM
it is easier to switch out parts with an experienced mechanic after you have developed a good working relationship, than it is to do it long distance.
Close enough to focus on these 2 bike's different styles insteadTig
Aug 22, 2002 2:12 PM
I don't think you can lose with either of these two models. I've heard many good reports on the Tuscany.

The compact vs. standard frame choice could affect the ride and your style more than a 1 degree seat tube angle. The compact should be a little stiffer when climbing and sprinting. The standard might be a bit more comfortable over a long ride and a little more flexy in the bottom bracket. A longer exposed seatpost of a compact might help soften the ride though. I bigger guy might want the stiffer compact. Then again, a strong, smaller rider might enjoy the compact frame as well.

I wonder if any of us would know the difference in a blind test? The actual weight difference can't be all that much either.
1 degreebic
Aug 22, 2002 5:57 PM
Not to be to much of a smart ass. But I don't think anyone who rides less then a pro would really know. With changing everything as you ride plus stem, seat, post set back etc etc. As to fitting, who knows the best way. Richard Sachs does not like the fit cycle ie stationary bike style of fitting. One's cyclists poison is anothers honey. :)
re: advantagecyclopathic
Aug 23, 2002 4:02 AM
if your femur is disproportional long you won't be able to get KOTS position on some seatpin/saddle combos with steeper seatangle. Shouldn't be a problem as you ride 74 now.

There should be other differences, bikes with shallower seatangle usually have longer chainstays and sometimes slightly shorter top tube. To accommodate shallow seatangle frame designers usually move BB shell forward in relation to rear axle, leave the rest same.

On either frame you will have no trouble to get into KOTS position. However, one frame can give you more balanced position then other one. Putting too much weight over rear wheel compromises handling.

Check the chainstay length. If you running seat all way back on your current 74, opt for bike with shallow seatangle/longer chainstays good luck
Don't you mean KOPS, or am I confoosd? ;-)nmLeisure
Aug 23, 2002 4:07 AM
yeap, didn't get my coffee yet ;-)nmcyclopathic
Aug 23, 2002 10:10 AM
effective top tube length...C-40
Aug 23, 2002 8:53 AM
There will be two differences in the bike's setup. Although both models have the same TT length, the Siena will require the saddle to be moved forward by 1.2cm to achieve the same KOP position as the Tuscany. This saddle movement effectively shortens the top tube by the same 1.2cm. The seatpost must be selected to insure that this amount of travel is available.

A 1cm longer stem would be used on the Siena to produce the same reach to the bars as the Tuscany.

Since you now have a 74 degree STA, take a look at the position of the saddle on your seatpost to see how it would look, if moved forward by 1.2cm.

If you select the proper stem and seatpost, you won't be able to tell any significant difference.
re: Difference between 73 and 74 degree seat tube anglerrodrigz
Aug 24, 2002 7:47 AM
I have only been riding for one year, but I am a physician and I think I can offer some thoughts. First of all, by going to a more "relaxed" angle you stress different muscle groups. I have a steel bike 75Degree seat angle. Recently I did a 40 mile hilly ride with a 73 degree angle bike. Added top tube + stem length were equal. The gluteus muscles and calf muscles got sore, but I definitely had more power on hills (higher speeds at the top of the hill).The 73 degree angle bike was easier to turn. Some may say that shifting the seat may accomplish the same thing but this fails to take into account the rest of the bike. If you change the seat angle, you also have to change the head tube angle or top tube length to keep the same wheelbase. The bike is a TRIANGLE and changes at the seat angle entail corresponding changes at the front end of the bike.This affects bike handling characteristics. Ride both bikes with a feel for overall ride quality rather than just one aspect.