-/+6 degree vs -/+17 degree what effects will it have?

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G6612
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Joined: Tue Aug 17, 2010 4:20 pm
Location: Pittsburgh, PA

by G6612

I have a cannondale supersix evo and I am running a 6 degree stem 100mm pointing down. I would like to get my bars a little lower as I am already against my top cone no spacers. I am thinking my reach is good so going to a 17 degree stem at 100mm how will this effect my reach. Will it make it longer or shorter? If I want or close to the same reach what length Stem should I get. I am running a 3T arx pro.

by Weenie


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eric
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by eric


numberSix
Posts: 124
Joined: Sun Sep 23, 2012 1:53 pm

by numberSix

Stem comparison tool link answers your question, so here's my trolling.

Under the 25mm high cone is a flat aluminum slam cap. You can delete the cone and drop 25mm without spending money.

Be aware, Cannondale wants the expander cap assembly to support the area inside the steerer clamped by the stem. This is only possible if the steerer is cut so the top cap is flush with the top of the stem. So no stack of spacers above the stem. You can test without the cut to see if you like the fit, but should probably avoid big sprint or standing efforts.

More trolling: this is your bike, right? http://weightweenies.starbike.com/forum/viewtopic.php?f=118&t=122990&p=1049307#p1049307
I have the same frame and am only a little taller and longer legged than you. I have way more seat post showing. So my question is has your fit been checked? Because that seat looks awful low.

ToffieBoi
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Location: Krakow, Poland

by ToffieBoi

Having a flat bearing cap, cutting the steering tube and slamming the stem down will give you a more rigid front end plus lighter bike.
Also you will spend almost nothing for the cap.

If your bars are still too high for you, then consider spending much money and going for -17 degree stem.

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G6612
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Location: Pittsburgh, PA

by G6612

numberSix,
I have always thought my seat looked very low, I am 5' 8" tall and have about a 30.5" inseam so in cycling terms I guess I am a little short. Every fitting I have had done and every calculation kind of puts me where my seat is. I have checked based on my height and it appears I should be on a 52cm frame, I am not sure I should be on anything smaller and honestly how much would that change. I would agree that my bikes have never had a lot of seat post showing do you think I should move it up? Appreciate you thoughts and may I ask what your measurements are and bike size.

numberSix
Posts: 124
Joined: Sun Sep 23, 2012 1:53 pm

by numberSix

5'9, 32" leg length, 52cm Evo HM
BB center to saddle top, through the seat rail clamp centerline, 745mm for a flat saddle (Selle Italia SLR) 750mm for a rounded or padded saddle (SLR Gel Flow, etc). Speedplay pedals. 175mm cranks.

Fit is of course way more complicated than saddle vs bottom bracket location, but the stem and bar location look reasonable. I doubt it's a frame size issue.
when you write 30.5" inseam, is that your true leg length?
what is the measurement from bottom bracket center line to saddle top horizon line? Run the tape measure through the center of the seat post's saddle rail clamp.

eric
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by eric

You need to measure your inseam the cycling way:

http://www.coloradocyclist.com/bikefit/#inseam-b

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G6612
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Joined: Tue Aug 17, 2010 4:20 pm
Location: Pittsburgh, PA

by G6612

30.5" is my true leg length against the wall with a book. Also I measured center of bottom bracket to saddle could not run a tape measure thru the seat. But from the side it measures 26.5".

numberSix
Posts: 124
Joined: Sun Sep 23, 2012 1:53 pm

by numberSix

Diagnosing fit over the internet is just a bad idea, but from the photo it just doesn't jibe with the measurements you've provided.

One of the old 'get in the ballpark' formulas is legLength X 0.883 = seat height, BB c/l to saddle top, measured up the seat tube.
I'm at 745mm / 813mm = .916
you're at 26.5" / 30.5" = .869

If you have someone local that's good at fit, IMO it would be worth your time. Coach, UCI mechanic, etc.
my $.02

Megaclocker
Posts: 150
Joined: Wed Dec 17, 2008 5:39 pm

by Megaclocker

I ride a 50cm supersix and I am about your height with same insearm.

Seat is about 1.5cm too high in the picture.

I think you want your handlebar lower because the headtube is most likely to long. (bike too big)

Image

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G6612
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Location: Pittsburgh, PA

by G6612

For ballpark figures I should do 30.5 x .883= 26.93". That should be my measurement from center bottom bracket to top of saddle correct??

Megaclocker
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by Megaclocker

G6612 wrote:For ballpark figures I should do 30.5 x .883= 26.93". That should be my measurement from center bottom bracket to top of saddle correct??


No idea to be honest.

I ride at 71.5cm seat height (Top of saddle - to BB axle).

sijray21
Posts: 5
Joined: Wed Jan 29, 2014 8:45 pm

by sijray21

OP - generally speaking, going to a 17* stem from a 6* stem will increase your reach slightly using the same length stem. Your bar-to-saddle drop & angle will increase (obviously) . If you go 10mm shorter on the stem it will likely bring your total reach closer than the current stem with 6* set-up.

numberSix
Posts: 124
Joined: Sun Sep 23, 2012 1:53 pm

by numberSix

G6612 wrote:For ballpark figures I should do 30.5 x .883= 26.93". That should be my measurement from center bottom bracket to top of saddle correct??


and typically add for the stack height of your shoe and pedal system. Sticking with inches that's about .375-.5".

I have no idea how many miles you have on your current fit. Changes of 4-5mm at a time is a lot. Put the bike in a trainer, move the seat height a little at a time, and see if higher works for you. Personal fit changes over time and fitness level. Keep of a diary of your present fit. If you do wind up almost an inch higher, the saddle will likely need to come forward a little.

The whole reason I dinged you on this is I can't believe you're not having knee pain issues on the present fit. You've got a great bike, it'll be worth it to get skilled help getting set up. WW has got some seriously knowledgeable cyclists, hopefully someone can suggest a fitter in Pittsburgh, PA to help you out.

best wishes
6

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Getter
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Location: So Cal

by Getter

I am also 5'8". My inseam is ~30in. My post is 69.4cm (measurement from fitter) from the center of the bottom bracket to the top of the saddle.

From what I've read...the .883 method sets your saddle too low.

My old and sold 52cm System Six, same geo as the Evo. I don't have much post showing either.
Image

by Weenie


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