Not getting any play on the General Cycling Board, so I thought I'd throw this out to the salty old grouches on C&V (this is a compliment!):

I used the fit calculator at Competitive Cyclist and I'm confused about something.

For the French Fit, which is what I am going for, it recommends a top tube of ~57 cm, a stem length of about ~11 cm, a saddle setback of ~5.5 cm and a saddle-handlebar measurement of ~57.

My current road bike has a 57cm top tube, the nose of the saddle is setback about 5 or 6 cm from the BB, and it is equipped with a 80mm reach stem that is set level with the saddle.

Now, currently it measures about 48cm from the nose of the saddle to the nearest point on the bars. For me to achieve the recommended 57 cm, I would need an additional 9 cm of reach on the stem. So, I'd need to find a stem with a reach of 17 cm, or 170mm.

Something doesn't compute here. What am I doing wrong? Any clarity on this matter would be gratefully accepted!

If it helps, here are the results as emailed to me from Competitive Cyclist:

The French Fit (cm)
-------------------------------------------
Seat tube range c-c: 58.8 - 59.3
Seat tube range c-t: 60.6 - 61.1
Top tube length: 57.2 - 57.6
Stem Length: 10.3 - 10.9
BB-Saddle Position: 78.4 - 80.4
Saddle-Handlebar: 56.6 - 57.2
Saddle Setback: 5.4 - 5.8
Seatpost Type: SETBACK

Do you feel cramped when you ride it?

In the recommendations, is there anything about seat tube and head tube angles? If the angles are equal and the seat is level with the bar tops it shouldn't matter, but I am just curious. It could impact the amount of seat set back, so I woud hope this would be part of the mix...

I am just guessing here, but I think I see the issue...

For the set back recommendation, it is probably meant that you should have a seat set back 5.5 cm from the center of the top of your seat post, not the cranks... At least this is what is done with a set back seat post. If you have it centered now, this gives you another 5.5 cm of total "length" so you only need an extra 3 cm of stem length.

If it doesn't provide (or ask for) seat and head tube angles, I don't know how it would specify set back, or stem length, so I could well be wrong in this.

EDIT: Looked at the list again. It does specify a SETBACK post... this is where the difference in overall length comes in... however it would be interesting to know what their assumed seat tube and head tube angles are, and they must be making some asumption on that to make a recommendation.

LittleDarwin,

Good points. I didn't find mention of tube angles. Perhaps they believe the range for these angles is close enough that it makes the differences negligible? Their output is a range, so that may account for variations in angle. As far as setback seatposts, I'm using a Laprade, which has a small (~3cm?) setback. The setback they recommend is based on a plumb line from the tip of the saddle nose to the ground. The distance from that line to the BB represents the setback.

I've always ridden poorly fitted bikes. They have always been functional, and they have never caused me any severe pain. However, I thought it might be interesting to try properly fitting a bike!

I don't feel particularly cramped on the bike I just built, and I actually prefer a slighly more upright position. However, I do feel somewhat cramped in the drops. I also think that on longer rides, I might find more comfort if I can stretch out a bit.

The one issue on the Batavus in question: the seattube is 2 cm shorter than recommended above. I know then that the rise in the stem will push the bars back toward the saddle, but the seattube angle is greater than the headtube angle, so it should actually result in an increased distance from bars to seatpost.

I had actually tried their fitting system, but I really had troubles getting accurate measurements without help... The things they wanted were definitely in the realm of only being accurate with someone else to do the measuring.

I also have never had a bike officially fitted. Of course I haven't ridden with drop bars for more than 10 miles total since I was in my twenties... back in the seventies... I will remedy that later this year.

I love reading some of the posts by people over in the roadie forum that treat the measurements as absolute instead of a good starting point... kind of like all the questions about whether a person should ride 175 versus 172.5 crank length... when they are 5' 4" tall with a 33" inseam and size 14 shoes... and people will actually disagree about the right length, and declare the truth for all people of those dimensions. And unless I was to look at the back of the crank arms, I would have a hard time seeing the difference between a 170 and a 175... and would never feel it while riding.

I say that just for the sake of the experiment then, that you need to set your seat back another 2 or 3 cm and then start your search for a 150mm long stem.

Good luck!

Point taken. Not looking for perfection, just wondering about this seeming oddity in fit recommendation. I'll ride it the way it is for now...I'm sick of spending money on this project and the bartape isn't coming off until it falls off! However, I'll likely try a longer stem the next time I change something up front. Just thought if I can peg an "appropriate" size I can keep my eyes open for something.

I agree with Darwin that getting accurate measurements is difficult without someone helping. And even then, I don't think my measurements were all that accurate, but they were closer. Another 7cm of reach sounds like a big jump.