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Does Wrenchscience.com sizing work?(12 posts)

Does Wrenchscience.com sizing work?Herms
Sep 8, 2003 5:33 AM
I am ordering a new Fuji road bike sometime this week. I am in between the 61cm (c-t) (59cm tt) and the 64cm (c-t) (61cm tt). I am 6'3.25'' with a 36in. inseam. I went ahead and did the wrenchscience sizing and it sized me for a 62 or 63 center to top frame size. As for the overall reach length: with the 61 I would need a 13cm stem and with the 64 i would need a 11cm. I could easily make either frame fit by making adjustments, but I'm just unsure which will be best for me. I have ridden a 61 fuji with 13cm stem and it feels great but I havent ridden the 64, so I can't tell which one will feel better.
-Also, I'm 18 yrs old and i suppose might grow a little more, but I doubt it.

Does anybody find wrenchscience's sizing to be wrong?

Anybody my size riding a fuji in either of these sizes?

thanks for the help
re: Does Wrenchscience.com sizing work?jzinckgra
Sep 8, 2003 5:52 AM
Funny you should post this. I used their fit system last week and I was surprised what frame size the program recommended. I'm 6'2", with a 33" inseam and currently ride a 56.5 C-C Klein, which fits me perfectly. After putting in the rest of my info, it recommends I need a 55cm C-C or a 56 or 57 C-T frame size. I was like WTH? This is way too small for me. The handlebar width suggestion was 46cm, which, again is too small (i use a 44cm and feel this is adequate). I decided to call wrenchscience on the phone. I told the guy about the overly small frame size that was suggested and he was like " Well we've been fitting hundreds of people using this system..blah, blah...". I guess that was some sort of sales pitch. Anyways, he said I must have made some incorrect measurements. Well, it's not too hard to make the measurements they need, so I remeasured and came up with the same #'s. I'm doubtful about their "system". Maybe for a new road rider, this may be a good starting point, but for me, having ridden about 5 years now, I knew this was way off. Anyways, if you can get yourself to a reputable shop and get fitted on a real bike, that would be the best way to get fitted.
6'2" with a 33" inseam? Are you sure?ET
Sep 8, 2003 10:43 AM
I'm 5'9" with a 33" inseam. OK, I'm a bit more leg than torso, but yours, if true, is way extreme. Plugging your height into ergobike's program gives an (average) inseam for that height of over 35". Even if true, that's so extreme I can't fault the program.
6'2" with a 33" inseam? Are you sure?jzinckgra
Sep 8, 2003 12:59 PM
Yes, I have a long torso (60"),but legs are out of proportion with my legs. And I'm more like 6'1.5" in height.
Oopsjzinckgra
Sep 8, 2003 1:00 PM
I meant to say that my torso is out of proportion with my legs.
Oopsjzinckgra
Sep 8, 2003 1:04 PM
Also, my 60" torso length is from the floor to the top of my sternum.
With the caveat the precise frame sizing is probably overrated:MXL02
Sep 8, 2003 5:57 AM
In general, for road racing, most people try to get the smallest frame possible, to increase stiffness and reduce weight. From my calculations, the 61 will probably fit you fine, especially if you've ridden it and liked it...go for it.
re: Does Wrenchscience.com sizing work?geeker
Sep 8, 2003 6:17 AM
Seems ballpark, though maybe biased to small "racing fit" frames (as opposed to Rivendell approach). One thing: when I tried the package, it didn't consider femur length (thus seat tube angle) at all, so it can't be comprehensive. I thought competitivecyclist.com's fit program was better. The Cyfac USA site also gets mentioned, but I haven't tried it.
not often...C-40
Sep 8, 2003 6:19 AM
About the only body dimension that can be measured with enough accuracy to be valuable is inseam. I use a bike with a horizontal top tube and block up the wheels until the TT exerts saddle-like crotch pressure when standing over the bike in bare feet. The distance from the floor to the to of the top tube is an accurate inseam.

Trying to predict stem length based on inaccurate body measurements is worthless. You need to get on the bike and try it. Stem length is greatly affected by saddle fore/aft position and the wrench science website does not take this into account. The starting position for the saddle places the knee directly over the pedal spindle. With riding experience, you may find that a position that is 1-2cm behind the pedal spindle is more effective. This amount of saddle movement makes a big difference in the stem length required. As a rough guide, be sure that you have some small amount of knee to elbow clearance when riding with your hand in the drops, fingers on the the brake levers and the uper back horizontal.

Another thing to measure is the vertical distance from the saddle to the top of the handlebars. Measure from the floor to the top of the saddle and the top of the bars and take the difference. If it's over 10cm, then the 61 is probably too small. You don't want to use a lot of steering tube spacers and a high rise stem to get the bars up to the necessary height.

There is a big 3cm difference between these two frames. It could be that neither one is a good fit. Another brand that has an in-between size may be worth trying.
biased toward small size framestarwheel
Sep 8, 2003 8:27 AM
Based on my experience, the Wre
biased toward small size framestarwheel
Sep 8, 2003 8:29 AM
Based on my experience, the Wrenchscience fit program is biased toward smaller frames -- that is, it will recommend a frame on the small side. In my case, this doesn't work because my bikes are set up with handlebars relatively high (small drop from saddle to handlebar). If I remember correctly, Wrenchscience recommended a 54 or 55 c-c frame for me and I am most comfortable on a 57 c-c frame. I think their program is OK if you are very flexible and/or racing and prefer a smaller frame for stiffness, light weight, etc. However, if you are more interested in comfort, I would take their recommendations with a big grain of salt.
Agreed, they like small framesJervis
Sep 9, 2003 7:44 AM
I'm 6' 2 1/2" and they say I need a 57 c-c, which is totally wrong. That's the frame size I ride now and it's way to small. I'm much more comfortable on a 58 or even a 61. Depending on whether or not you race of course, ride what's comfortable.