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One more in need of fit help!(11 posts)

One more in need of fit help!Triphop
Aug 19, 2003 8:21 PM
If you knowledgeable folks here wouldn't mind assisting another in need of fit help, that would be greatly appreciated.

I am looking into purchasing a Fondriest 60cm frame and am unable to test ride one first. I am right on the cusp for this size and am nervous it may be too small. I have seen that a number of you have bought frames without test rides, and to be honest, I am a bit nervous of doing the same.

The top tube length of the frame is perfect, with a 110 stem my reach would be ideal. The problem is the seat tube, the frame measure 62.5cm c-t, and 58 c-c. My inseam is 90cm, long legs. My calculations show that a 62.5 c-t is correct, but that in c-c measurements I should be looking at a 59 or even a 60cm c-c.

I suppose my question is will a 60cm frame be too small? I understand the problem with too small a frame results in having to jack up the seat, creating a large seat to bar drop. Here are the dimesnions of the frame.

any help is greatly appreciated!

Seat Tube C-C 58
Seat Tube C-T 62.5
Top Tube C-C 58.5
Seat Tube Angle 72.45
Headtube Length 192
BB Height 26.5
may be too big....C-40
Aug 20, 2003 5:32 AM
You cannot apply normal formulas to sizing a sloping TT frame. The Fondriest has a 5cm slope on the TT. The c-t seat tube length will be a full 5cm less than normal formulas suggest for the frame size.

For example, I ride a 54cm (c-t) conventional frame and a small size, 49.5cm (c-t), Fondriest.

What you should take a careful look at is the head tube length, with the headset (220mm). Compare it to the head tube length of your current ride (if you have one). The problem with a small frame is not "jacking up the seat" - the saddle height, remains the the same (from the bottom bracket) regardless of frame size. The problem with a small frame is a short headtube length that drops the bars too low.

Another way to determine frame size is to measure saddle height and subtract 17-18cm for a conventional frame. For a 5cm sloping frame, subtract another 5cm. An XL size Fondriest would be good for a saddle height of up to 82cm. An L size would accomodate up to a 78cm saddle height.
may be too big....Triphop
Aug 20, 2003 6:24 AM
C-40...thanks for the reply, I was hoping you would, as I have read many of your responses regarding fit, you seem to be very knowledgable.

The Fondriest I am looking at is the Status Carb which according to their website is standard geometry not sloping. That being the case, what are your thoughts?

Using your method of determining frame size by subtracting 1-18cm from saddle height, which for me is 80cm, puts me at a 62cm frame.
the headtube is shorter....C-40
Aug 20, 2003 9:01 AM
The Status Carb does have standard geometry. Conventional frame sizing would suggest a c-t frame size of 90cm - 29cm = 61cm. Subtract 1.5cm for a c-c size of 59.5cm. The size 60 only measures 58cm c-c. Big guys with long arms can often ride a least another cm smaller. IF you have properly measured your inseam to hard crotch contact in bare feet, then the 60cm is on the small side, but may be tolerable depending on how agressive and fit you are. If you're on the recreational side of fitness, it's probably too small.

The sloping frames in the XL size are actually 2cm larger (vertically) due to the 2cm longer head tube and would probably fit better.

The critical thing is your inseam measurement and a saddle height measurement. People often make errors of 1-2cm when measuring inseam (usually low). This can result in a frame that's too small. A saddle height measurement may be more reliable.

Taking measurements on an existing bike that you have been riding is another good way to determine if a new frame will fit. If there's something not right with an existing bike, now's the time to find the geometry that will correct the problem.
Based on what I just went through..........davet
Aug 20, 2003 6:44 AM
..the 60cm Fondriest may be a tad samll. I just had a custom frame built for me, it fits perfectly. My inseam is 88.5cm and my bike is a 61cm C-C with a 58.5 top tube. Looking at the geometry charts it doesn't appear they offer anything larger than a 60cm. It actually sounds like you should be on a 61 or 62cm C-C frame.
I think(?) something is not adding up correctly...B2
Aug 20, 2003 3:58 PM
If you have a 58cm c-c & 62.5cm c-t seat tube, that means that the radius of your top tube is 4.5cm and the diameter is 9cm???

At any rate, with a 90cm inseam, wouldn't you want to start looking at something around 62cm c-t? If the ST is in fact 62.5cm c-t it sounds like you're in the ballpark. Have you attempted to calculate the saddle to bar drop?

To add to the uncertainty...Triphop
Aug 20, 2003 6:50 PM
..I have been in contact with Fondriest, and gave them my measurements. They are saying that the 60cm may be too big and that I should consider the 56cm! They are basing their suggestion on reach rather than standover, so with a 56c-c TT plus a 120mm stem that gives an overall reach of 68cm. Then further compensate by sliding the sddle back 5mm from center..which isn't so terrible as I like my knee behind the spindle anyway.

Ugh! I ride a 58cm c-c TT bike with a 110 stem now, and feel it's too small, I feel cramped in the cockpit. Well, I figure I will go down to Fondriest in Denver and try out a 56cm, let them fit me to a frame and see how it feels. I'll let you all know what I find out.

Thanks for the responses, I appreciate it.

for anyone who wants to mess with the numbers my measurements are below, and the frame dimensions for the Status Carb can be found here:

6'1/2" tall
90cm inseam
26.25" arm (rib cage to web b/t thumb & forefinger)
61.5" from ground to sternum notch
Good flexibility - can touch my toes
Aug 20, 2003 7:03 PM
...sternum notch measurement is actually 60".
forgetting the head tube length???C-40
Aug 21, 2003 8:44 AM
Don't let some guy talk you into a too small frame, based solely on TT length. When you correct for the difference in seat tube angles between the 58 and 60 sizes, the 60 has a 1cm longer top tube than the 58. As you noted, the saddle will be pushed back a bit more on the 58 (more like 7mm) to achieve the SAME KOP postion as the 60. Moving the saddle back 7mm on the 58 will not move the knee further back relative to the bottom braket.

The big difference is in the head tube length. Get a head tube too short and you will have a stupid looking bike setup with lots of steering tube spacers and/or a high rise stem.

If you can actually get on a bike, check the height of the saddle above the top tube, with the saddle height set correctly. It should be in the range of 17-19cm. A saddle set at 17cm above the top tube will produce a 9cm drop to the bars with an 84 degree stem and no spacers. If the saddle is higher than 17cm or you need less drop, then you're into spacers or the high rise stem.
forgetting the head tube length???Triphop
Aug 21, 2003 9:19 AM
C-40 -
I think you are right on with your concerns about HT length. I ride a 58cm c-c ST & TT frame currently, with a 110 quill stem. I feel it is too small due to having to raise the seat to a height to accomadate my long leg length (didn't measure the seat to TT), which in turn has forced me to raise the stem as high as it can go, so my drop isn't absurd. My current drop is 3.5". But raising the stem has shortened the effective top tube length, making me feel cramped in the cockpit. I suppose I could always get a 120mm stem to correct for this.

I am going to get a proper fit saturday morning, so I can make a fully educated and confident decision on buying a frame. This is too much $$ to not come out 100% satisfied. I am thinking I may just scrap the Fondriest idea (although I do so like it) and search for a comparable alternative, that I can hopefully test ride!

What are your thoughts about the Torelli Express?

btw - they were telling me to look at the 56cm not 58cm!
seat tube extension !!!C-40
Aug 21, 2003 8:33 AM
The frame can be 58cm c-c and the seat tube can easily be be 62.5, if it's extended above the TT, which is very common these days.