Originally Posted by jazzy_cyclist
I am looking at building up a frame over the winter, so another approach that I'm working is frame geometry with a shorter top tube and/or longer head tube. It's difficult to get a sense of how big a difference this will make in the end -- right now it's just a spreadsheet of numbers for different frames compared to my current ride.
Curious if others have gone this route and what the results were...
On actual seating and riding position, it will not matter if you have a shorter top tube and longer stem on the comfort stakes. What it will have an effect on though is the steering. More weight will be on the front wheel. I know that on a mountain bike, where steering has to be effective, I often have to lean forward on fast corners to weight the front wheel to get just that little extra grip, as I have a short top tube and shortish stem for comfort. When I used to race, I would have the bike set up with a 30mm longer stem to that now fitted, and the bars were also 50mm lower. This in effect gave me a heavier front wheel for the higher speeds. For the XC longer rides that I now do, and an older body of course, if I set the bike up in racing mode, it would not be comfortable for long.
Once again in mountain biking frame of mind, The short tube-long stem were an advantage uphill, but I would have to get my butt off the rear of the saddle for the downhills. With my current set up of short tube-short stem, I do not even think about the downhills (Except where grip will be at a premium so I lift the body forward) and take them in a comfortable position, but have to take a bit of care on the steep uphills, as the front wheel has a tendency to lift and hence losing ALL grip when power is put in.
Then the other disadvantage of smaller frame to give the short tube is that it will normally be a smaller frame. Offroad a small frame is an advantage on handling but the length of seat stem means a heavier grade of seat stem to be used, or higher quality/cost seat stem to keep the weight down Then that tight triangle is very stiff. Ideal for power transmission to the back wheel with no frame flex taking power from the pedals, but gives a harsher ride at the same time.
Hate to say it, but look at and try the frames and bikes around in the shops, and see what is comfortable for you. Look at the reputation of that bike, and see if it is noted as being a flatland bike, a hill climber, or a short distance speed bike. Then work out what you think will be the ideal set up for you.