Quote:
Originally Posted by Doug Fattic
I don't think you have provided enough information to give a complete evaluation. My impression of Paceline posters is that they are a more go-fast (or at least look-fast) crowd than say the people over on the I-BOB list - where you might get slightly different comments. Anyway I'm a long time builder and will only build a frame after I have done a fitting or know who the fitter is. I don't think you have enough information unless you have a fit done.
I'm suspicious that your 74ยบ seat angle might be too steep. It might be the right angle but that depends on the kind of riding you do - which I don't remember you telling us. The reason I think it might be too steep is because your handlebars are level with your saddle and that isn't where fit go-fast guys want their bars. It is where no-longer-skinny older and less flexible recreational riders like their handlebars. Your body shape and age play into your saddle position. For example if your upper body is carrying extra pounds, you should find out where your saddle setback balances your weight over the pedals. That reduces the load on your arms supporting your upper body weight.
I'm 5'8" too but my saddle height along the center of the seat tube line is 73.5. I use 170 cranks and prefer a much lower BB height than your 270. That is production frame height where the designer doesn't know if you are using longer cranks and pedaling through corners. Custom frames (and especially small custom frames) can lower the BB height if they are using shorter cranks (and seems like, with your short legs, 165 cranks are more than long enough) and you are not riding in pace lines pedaling through corners. A lower BB height means a you can straddle a bigger frame which means you can have a longer head tube which reduces the need for more head tube extension above your top tube.
All frame designs involve compromise. If your saddle position after a fitting shows you need a shallower seat angle, then using 700c wheels is a compromise. I'd consider 650B X 28 or 32. Smaller wheels are an advantage for you except for shopping convenience. If you are going with 42s, than they are the same diameter as a 700C by 28. The radius of the tire you chose (345) is the radius of a 700c X 32 tire. Is this the size you chose? A 28 is 340 (this all depends on the brand of tire of course). The radius of a 650b X 28 (they make them) is 320. That 20 mm can help in several ways making a smaller frame.
I think this whole exercise is pointless unless you go get a fitting first. So far you are fitting your body to a design instead of designing a frame to fit your best cycling position. This is especially true as we age. We get fatter, less flexible, want to be more comfortable and are less concerned about shaving a few seconds off of our regular route. I've had hundreds of students take one of my framebuilding classes. It is the rule rather than the exception that they learned their present position was not optimum and required adjusting their new frame design compared to what they expected. The problem was that their current bicycle prevented the from finding they best position. For example their seat angle was too steep. Just to be clear if you are a fit go fast kind of guy, than it is better to fit the body to the frame designed for handling and speed rather than comfort. My guess is that your 1st priority is comfort.
|
Doug,
Thanks for the thoughtful comments. I will try to address as best I can.
I am 64 years old. In my 20's I used to race and in my middle age (30-50) I would go on fast group rides and ride at my limit. I am now at the point where I ride much slower due to age, injuries and health problems. Even though I am riding slower I enjoy it just as much or more. I am not fat or overweight, I weight about what I did 20 years ago which is 140lbs. There are times where I like to push myself but that is only for short periods. I already have what you call a "go fast" bike which is a Cannondale EVO. This bike is to be a complement to that bike being steel and have a more relaxed geometry. Also being a second bike I have a limited budget. I realize that many here have unlimited resources to pick any builder and get a fitting. I simply do not have $5K to spend on this. So lets just call it a semi custom bike. I am going to very lucky if my wife even lets me go ahead with this.
Even though we are the same height we have very different proportions with your saddle being over 3 inches higher than mine.
My whole life I have ridden 170mm cranks and I am not going to change that now. The BB is actually lower than my Cannondale by 10mm. Most of the bikes I have had have a 74 STA and it works fine for me. In fact I usually use a zero offset seat post. Making the STA slacker would push my saddle further back which could be problematic. I have pretty much settled on 28c tires as I ride only on the road. I have recently spent a lot of time learning about geometry and have a lifetime of experience adjusting the fit on my bicycles. I have serious doubts that a fitter is going change anything substantial. There are not that many around and how do I know if they are any good? Not trying to be cynical here just putting down my thoughts.