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Discussion Starter · #1 ·
I'm 175cm/5'9, and have the possibility of buying a Look 585, medium (53) or large (55). The problem is that I have for a long time been using what was my brother's bike that was too big, so I don't really have any of the measurements everyone talks about accurately: drop, saddle height, etc. If it helps, I do know I usually ge the short 30 inch lenght for jeans and pants. So, 175cm, and legs on the short side, perhaps. I know I don't want a huge drop to the handlbars, but a racy position is fine. So, medium or large? I am asking about the frame, and then I can make adjustments to things like stem, etc. Would that be the right way to think bout it?

Any quick replies would be great cause the decision will have to be soon here.
Thanks.
 

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dumalam said:
I'm 175cm/5'9, and have the possibility of buying a Look 585, medium (53) or large (55). The problem is that I have for a long time been using what was my brother's bike that was too big, so I don't really have any of the measurements everyone talks about accurately: drop, saddle height, etc. If it helps, I do know I usually ge the short 30 inch lenght for jeans and pants. So, 175cm, and legs on the short side, perhaps. I know I don't want a huge drop to the handlbars, but a racy position is fine. So, medium or large? I am asking about the frame, and then I can make adjustments to things like stem, etc. Would that be the right way to think bout it?

Any quick replies would be great cause the decision will have to be soon here.
Thanks.
If you are going to buy a quality bike like a LOOK then it would be a good idea to have a quality fitting. Its like buying a $10,000 suit without getting measured up for it. That being said and you want to take a chance, then i am 177cm tall and ride a Medium and won't even look at a large.
 

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Discussion Starter · #3 ·
I just tried a Medium 555 and it felt pretty good. Certianly not too small, though now I am even wondering if a Small would be good. The saddle on the M was lowered a bit for me. Would a Small defintely be too small? I saw and I think I'm right that the 555 is pretty much the same geometry as the 585 right? I will try to get fitted as/before I buy the actual frame too. Any more thoughts?
 

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I am 5'9" and am riding a Small (51cm) 565, and the fit is perfect. I discovered that the head tube on the Med was too tall and would not allow the proper seat to handlebar drop. For me, setback is fine even with a Thomson zero setback seat post.
 

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the problem...

Most likely, the small size fits your leg length best. To know for sure, you at least need an accurate saddle height. Even then, the choice boils down to how much saddle to handlebar drop you can tolerate. Both sizes can be made to fit the same. The size M will require one size shorter stem and the head tube is 23mm taller.

FWIW, if your saddle height is around 73cm, then the small could be setup to produce a drop of 7-8cm with the maximum 3cm of spacer, 5-6cm with a flipped stem. If your saddle height is more than 73cm (not likely) then the medium frame would be the best choice. The medium would also be the better choice is you want a handlebar drop in the 5-6cm range.
 

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Discussion Starter · #8 ·
Well, I had some measurements done and recomendations from the program the shop was using. It said that I need a 71cm saddle height (saddle to bb) with a 170mm crank length. That seems to suggest a small would be good, from what I understand from you, C-40.

However, and I don't remember the specific measurement, but the conclusion was that on the medium, I would need a 120mm stem. The medium has a 545mm top tube. They said that the small would have too short a top tube for me, meaing I'd have to use a 130/140 stem. And that is for a not so racy position, with a 2-3cm drop. With a race position, the recommendation was a 7-8cm drop and an even slightly longer stem (still on the medium). And I am not looking for a huge drop, maybe in between, about 5, but I would need to play with that.

Any thoughts? It seems that for height I could do both, probably somewhere in the middle, but the medium seems better for length. What's more important for fit, height (seat and head tube) or lenght (top tube)? And is that the right question? Hmm, how philosophical.
 

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thoughts...

Figuring the proper saddle height is not hard, but programs that attempt to estimate stem length are usually not accurate. Did someone take an accurate measurement of your upper leg as part of the fitting? If not, then they have no idea where the proper saddle fore/aft position will be and that greatly affects stem length.

If your saddle height is only 71cm, the medium size is too tall. It would be on the large side even for my 73cm saddle height.

Other factors that affect stem length and usually overlooked in fittings are the handlebar reach and the brand of brake/shifters being used. There are a few models of handlebars that can add up to 10mm of reach and Shimano brake/shifter levers have about 10mm more reach than current Campy models.

The small size only has about 8mm less reach than the medium, due to the difference in the seat tube angle. I would get the small and use longer reach bars, but only if a 130mm stem proves too short, but I doubt that it will. When setting the saddle fore/aft position, go for a little further back position, rather than a strict knee over pedal setting. KOP is only a starting point and not something that's a must for efficient pedaling. With the 74.5 degree seat tube angle on the small size, be sure to get a seatpost with 25mm or more of setback. I like the FSA K-force light models, that can be had in 25 or 32mm of setback.
 

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Discussion Starter · #10 ·
C-40, I appreciate your advice. After speaking with and seeing more people, I understand that, like you said, it it boils down to how much sadde-bar drop I want. Reach (TT) works with both. The problem for me is that I don't know how much drop I want. But what, according to the geometry and my numbers (saddle height of 71/72cm), is biggest drop I can get on the M (without spacers and a horizontal stem), and what is the smallest drop I can get on the S (with say 2 or 3 spacers and an angled stem, but not a crazy angle)? Any ideas?

Now, how would be the best way to determine what kind of drop I need? Unfortunately I have been riding bikes that have been too big for me for years, which gave me small drops. They were fine and comfortable, but now that I'm investing a lot of money in a new bike, I want to get it right. Ideally, I suppose, would be to have a frame, that with my saddel height, would have a range of say 3-9cm, where I could use trial and error, even after buying the frame and bike. And that I could change as I improve flexibility and competitivness. But from what I can see, the M would give a max of about 4 or 5, and the S a min of about 6 or 7. What do you think?
 

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answer...

Assuming a 71cm saddle height, the small size could produce a saddle to bar drop of only 5cm with the maximum 3cm of spacer and an 84 degree stem. That's not much drop at all.

The medium size frame can provide a maximum drop of 8.5cm, if you install a headset with a shorter 8mm top section, use no spacers and a 73 degree stem.

Another way to think of the bar drop situation is to compare the head tube lengths. The small size maximum HT length is 170mm with the headset and 30mm of spacer. The medium size has a minimum length of 156mm, if you install the shorter headset, otherwise, the minimum is 163mm.

FWIW, I only use a 145mm total length with an 84 degree stem and my saddle height is 74cm. Of course that produces a drop of about 10.5cm. I raised my saddle about 1cm this year and never changed my bar height. It's caused me no discomfort, but I make sure that my saddle is far enough back so I'm balanced with little weight on my hands.

I still think the medium is too large for your saddle height.
 

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Discussion Starter · #12 ·
Thanks for the help. If nothing else, I finally feel I have a pretty good understanding of bike geometry and fit. Much more than before, anyway. Thanks for all your advice. I'll let you know what happens.
 
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