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For C-40 and the geometry Allstars(14 posts)

For C-40 and the geometry Allstarsmainframe
Dec 5, 2002 8:53 AM
Would like comments on the following setup. My cycling inseam is 33". The frame is 55cm c-c, 7cm BB drop, 133mm HT length. Saddle top is 19.4cm above top of TT resulting in a drop of 9.5cm at the bars with 1" of spacers on the steerer tube and a Thomson 80 degree 120mm stem. Standing over in bare feet presses privates/soft tissue gently but definitively against the TT. Reach across the 565mm TT provides good relationship between elbows/knees when riding. KOPS relationship is good, allowing for painfree spinning or power riding. Is 55cm too small?
short head tube, but not too small....C-40
Dec 5, 2002 9:13 AM
A 55cm frame would typically have a head tube length close to 150mm. Do you happen to have a LOOK frame? Your head tube is on the short side, which explains the need for 2.5cm of spacers. It would be better to use a 130mm stem, like a Ritchey WCS, flipped over to a 96 degree angle to keep the bars up and reduce or eliminate the spacers.

The frame is not too small in the vertical direction. Standover height on a 55cm frame would typically be about 81cm, which would yield 3cm of clearance to hard crotch contact. Certainly not excessive.

Your saddle height above the top tube is on the high side. Mine's only 17cm above the top tube and I've got 1cm more standover clearance, a difference of over 3cm. You don't mention the pedals and shoes that you use, but Speedplays with Sidi shoes can reduce saddle height up to 1cm over other combinations.
short head tube, but not too small....mainframe
Dec 5, 2002 9:28 AM
Thanks, as always, for your prompt response. The frame described is a Lemond steel. I have over the past two years of riding determined, as you noted, the TT could stand to be longer. I have in my possession a Look 361 which, when STA is factored in, will yield an effective TT length gain of 4mm. However, the Look HT is 3mm shorter which will increase drop slightly assuming the 1" of spacers remain. Shoes are Adidas and pedals are Look.
..I was just going to say it sounds like Lemond!!Spunout
Dec 5, 2002 9:33 AM
I also ride 55 X 56.5

It is true, the head-tubes are a little less-tall I use a Thomson 80 (or is it 100) to give positive rise, 110mm, with no spacers. This gives me an aggressive riding position for sure(with Look pedals to boot). Lots of drop, I don't need any more for sure!
..I was just going to say it sounds like Lemond!!mainframe
Dec 5, 2002 10:28 AM
I believe Thomson makes only two road stems, one is 80 deg., the other (yours) is a five deg. rise from 90 deg. What is the distance between your saddle top and the top of the TT? Further, with your Thomson riser and no spacers, what is the measured drop to your bars?
Saddle +21cm above TT with 10cm drop, Thomson +5 deg. K? NMSpunout
Dec 5, 2002 6:16 PM
TT length loss, not gain...C-40
Dec 5, 2002 11:26 AM
If you have a 55cm LOOK with a 56.9cm TT and 72.5 STA, you should subtract .6cm from the LOOK's TT length to compare it with the 73 degree angle of your Lemond. The "effective' top tube length would be 56.3cm, or 2mm shorter than your Lemond.
TT length loss, not gain...mainframe
Dec 5, 2002 11:40 AM
Yes, but I was assuming moving the saddle 6mm forward to maintain the same relation to the BB/spindle. Would you not have to re-set the saddle position forward to compensate the 0.5 degree change in STA? As you've stated in the past, 1 degree of STA = 1.2cm, thus 0.5 degree = 6mm?
TT length loss, not gain...mainframe
Dec 5, 2002 11:46 AM
Disregard, I see your point.
re: For C-40 and the geometry Allstarskoala
Dec 5, 2002 10:01 AM
I, too have a cycling inseam of 33, ride a 55c-c and have a bottom bracket drop of 7. My crotch clears my top tube with cycling shorts entirely. What am I missing? Standover is 80.8 cm.
Forgot-headtube is 14cm.n.m.koala
Dec 5, 2002 10:02 AM
Forgot-headtube is 14cm.n.m.mainframe
Dec 5, 2002 10:33 AM
FYI, Lemond geo. table states standover at 803.
re: For C-40 and the geometry AllstarsJohnG
Dec 6, 2002 7:57 AM
Keep in mind the C40 TT is 1 cm lower than the stated "size". I.e. a 55cm frame has a TT that's at the same height as a 54cm steel Colnago.

I have a 32" inseam and use a 54cm CT1 (similar sizing to the C40) and have plenty of standover clearance. With a 33" inseam you'll likely have a BIG saddle to bar drop with a 55cm frame.

I'd recommend a size 57cm C40 for you......... given your huge saddle/bar drop with your current bike.


Mainframe, how do you like the KG361...serbski
Dec 6, 2002 8:03 PM
...compared to the LeMond? I ask because I rode a borrowed 55cm Zurich until I recently purchased a 56cm KG361 and am curious as to your take on their respective fit, comfort, handling and climbing characteristics. My inseam is slighty longer (86cm) so I went up a size but the resulting set-up (saddle height/20.5cm, drop/10.2cm etc) is rather close to yours, however, I'm wondering if I should have gone to the 55cm, just for more clearance and to have a smaller frame. Just interested in hearing what someone in a similar bike scenario has to say... Oh, and any idea on the standover on the Look as that's not printed in any of their geometry charts. (and if you still want to go up a size maybe we can work a swap). C-40, please weigh in here if you'd like...