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Help me figure out what size Look 381 to get?(6 posts)

Help me figure out what size Look 381 to get?my327vette
Apr 15, 2003 6:49 PM
Hi, I am going to purchase a 2002 Look KG 381i frame, but I am not sure what size to get. I want to purchase it online, so I will not be able to go to a shop and get fitted for it. I currently ride a size 54 Trek 5200 which fits pretty good but almost a hair too small. I used to have a size 56 Trek 5200 which was a little big for me. Can anyone help me figure out what size to get? Thanks!
re: Help me figure out what size Look 381 to get?Ian
Apr 15, 2003 7:01 PM
Probably a 53 based on what you say about the Treks, but (and this is a really big but), go to a shop and get sized if you do not know what size to get. Frame size is everything. A fitting might cost you $100, but it will be well worth it when purchasing a $2,000 frame.

Ian
re: Help me figure out what size Look 381 to get?look271
Apr 15, 2003 7:41 PM
You know, we went over this several times on your previous post. I gave you the link to the geometry chart for Look. Measure your 54 Trek. Look at the chart. Get the frame that is slightly larger than your Trek's 54. My guess (again) is that it will be 53. Buy the d#$m bike. Build it up. Show us pictures!
Wrenchscience.com fittingpitt83
Apr 16, 2003 4:58 AM
It was really close to the $125 fitting my shop did. That may help. And yes, read the geometry chart and measure what you already knwo. You should get close.

My soapbox answer:
My LOOK was the same price at the shop as on-line. Shipping and tax were a wash. Considering what services the shop gives, it may not be worth buying on-line for a few $.
an accurate comparison...C-40
Apr 16, 2003 5:16 AM
You are comparing frames that have the most extreme difference in geometry as any two on the market. You would need to provide more info regarding you stem length and angle, the amount of head tube spacers that you use, the vertical height of your saddle above the top tube and the head tube length of the Trek to make a truly valid recommendation. You also need to consider the location of your saddle on the seat post. If you get a LOOK, you will have to move the saddle forward by almost 2cm to get the same position relative to the BB. You may not have this much adjustment available.

You might want to consider the new LOOK KG461. It has geometry that is more like the Trek. It's also a lot cheaper and not much heavier.

Comparing the vertical dimensions of the two frames, a 51cm LOOK 381 is equivalent to a 54cm Trek and a 53cm LOOK is equivalent to the 56cm Trek. A 52cm LOOK would be in between.

Comparing the effective top tube lengths is another story. The LOOK top tubes are a lot shorter. The 51cm LOOK has TT length that is effectively 1.8cm shorter than the 54cm Trek. A 20mm longer stem will be required.

The TT lengths of the 52 and 53cm LOOK frames are only 10mm shorter than your 54cm Trek. The head tube lengths are 129 and 143mm respectively.

The LOOK frames have integrated headsets. The headset will only add about 5mm to the length of the head tube. A conventional headset (used on the Trek) will add at least 25mm to the length of the head tube. With an equal head tube length, the LOOK frames could require 20mm more head tube spacers or a 96-100 degree stem to get the bars up to the same height.
Look side question...Spunout
Apr 16, 2003 5:46 AM
Looking at the numbers, the Look has a longer TT, but because of the slack angles, it is actually less.

http://www.competitivecyclist.com/bike_look.htm#Geometry

But, look uses one set of lugs to make two sizes of bikes, look at the 55/56 for example. It is possible to add HT height without lengthening the TT. This is sort of a multi-geometrical line, I like this alot as an option. My Lemond is great, but so short in the HT for the TT length. Spacer city!

One more reason why Colnago geometry looks better all of the time. I'd ride a 58 (C-T) Colnago as opposed to my 55 (C-C) Lemond. Benefit would be 2cm more head-tube for similar effective TT.

Thanks for looking, C-40.