different bikes, same position

[Climb01742]

what's the best way to replicate the same position on different bikes? i have my three points of contact dialed in pretty well (saddle height, saddle to bar reach, and saddle to bar drop.) but that "triangle" can slide around a bit, based mostly on different seattube angles. it seems like the best place to begin is setback. since i use the same saddle on all my bikes, i'm measuring it-- the distance from center of BB to tip of saddle. on the frames that fit me the best, the setback is 80 mm, give or take 1 or 2 mm. is setback the best place to begin? if not, what is? many thanks.

[e-RICHIE]

80mm!??

are you sure? that's lots, unless you're really tall, have longer than average femurs, big feet, and/or a woman's saddle.

go check it again while i watch Inside The Actor's Studio.

e-RICHIE

ps

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[jdesalvo]

Here is a method that works pretty well. It assumes that you use the same kind of saddle, the same length cranks and the same pedals on each bike and that you start by measuring from the bike that you want to replicate on the others. First, make sure your bike is on level ground. If you have a horizontal top tube, you can simply place a level on it to verify that the bike is level. If you have a sloping top tube, you must measure the distance from the center of BOTH hubs to the ground -- if the bike is level this measurement should be the same. Next place the cranks in line with the angle of the seat tube. The bottom pedal will be the farthest distance from the seat in your pedal stroke. Let's call this your "saddle height" and can be measured from the middle of the pedal spindle to the top of the saddle. Next you'll need to rotate the pedals into the "3 and 9 o'clock" positions. Drop a plumb line from the tip of the saddle down to the pedal. Measure the distance behind the pedal that the plumb line falls. Now place a yard stick on the sadlle going forward towards the handle bars. Make sure that the yardstick is level. Determine the height difference between the top of the bars and the top of the saddle. Finally measure from the tip of the saddle to the point of each brake hood (make sure that the front wheel is aimed straight ahead). These two numbers SHOULD be the same if the brake hoods are set up right. Match these measurements on all of your bikes and you are as dialed in as you can be...GOOD LUCK!

[CarbonTi]

The best single measurement combo would be the saddle height and the saddle setback from the BB. If you use different saddles you might have to fiddle with the setback to get the position where you perch to match across different bikes. Once you have things squared away in the engine room there's a lot more leeway in how the other dimensions are set.

The other dimesions that I find important are:

a) the reach measurement from the saddle tip to the point of the brake hoods. I don't use the point where the bars clamp on the stem to measure because different bars differ in reach and also ignores the reach to the brake levers in riding the hoods.

b) saddle tip to the handle bar drops. To make sure that the drops are actually useful. I can run more reach (and drop) on the stem dimensions with modern shallow bars than on Cinelli 66-42's of yore but the overall reach measurement is basically the same.

80cm of saddle setback is a fair amount but it may work for you. Hinault's position was given by Genzling to have 7.5cm of setback for the 54cm frames ridden by Le Blaireau. So he had long femurs or liked to motor sitting way back there.

[Climb01742]

richie--i rechecked it. 80mm it is, at least how i'm measuring it. i do have long femurs. aliante saddle. and size 45 tootsies. the frames this setback is from all have 72.5 ST angles. two are custom serottas. according to the build sheets, serotta's calculated setback is 16.69. i do like to be back. i'm taking one of my frames to my LBS today and have someone other than me measure the setback.

[Kevin]

Climb,

You think that you have long femurs, the calculated setback on my two Serottas is 18.75. Considering that I am only 6 feet tall, you could say that I am all legs. It does make buying a bike rather difficult. Thankfully there is Ben.

Kevin

[David Kirk]

I've got a dollar that says that Climb and Richie are measuring set back differently.

I'll bet Climb is measureing with a plumb bob from the tip of the saddle and Richie from the seat lug center.


Am I right ? Do I get a treat ?

Dave

[e-RICHIE]

negative.
his saddle is 8cm behind the bb vertical line.
he followed up with his actual setback of the frame. it's 16.69cm.
i had 5 years of french in high school. this was too easy.

e-RICHIE

ps

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[csb]

[e-RICHIE]

there's :no: fooling you, eh?!

e-RICHIE

ps

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[Climb01742]

dave is right. as is richie. went to my LBS last night and my measurements were accurate. 8 cm back from center of BB to saddle tip. but man, using plumb lines accurately is tough. we also tried it with a laser level thing. but anytime you use human hands, being accurate ain't easy. here's a weird idea: i bet you could design a neat pattern to go on the top of the toptube where the builder could mark the center of the BB. kind of a bullseye thing to help setting up saddle position. overkill probably but could be helpful.

[e-RICHIE]

snipped:
" here's a weird idea: i bet you could design a neat pattern to go on the top of the toptube where the builder could mark the center of the BB."


climb-issimo,
don't ever assume that the top tube is level or that the ground is. even using a level will not dial in the setback measurement to the mm dimension that is critical for the comparisons you are seeking. my setback measurements are fixture specific, and if i didn't know what i set it to, it would only be a guess to determine it after the fact.

e-RICHIE

ps

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[Climb01742]

so richie--any suggestion(s) for getting the same position on different bikes other than beginning with setback, or is that, despite its flaws, the best place to begin? and no, buying only e-richie frames isn't an option. :p i haven't got a million years to wait.

[e-RICHIE]

yes - i think the fit-stick tool is a good "aid".
i've only seen pics, but it looks workable.

e-RICHIE

ps

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[Climb01742]

richie--i'm not familiar with it. what does it do? thanks.

[e-RICHIE]

here:
http://www.cyclemetrics.com/

e-RICHIE

ps

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[sharky]

here is another one for you to play with climb-- since your triangle moves around a bit, check it out and compare it on different bikes by measuring the distance from your front axle to a plumb line down from the tip of your saddle. take this as a percentage of your wheel base. my best balanced bikes have 59.5 to 60% in front of the saddle. any more than this and the front end gets a little twitchy.

[Matt Barkley]

Climb,
Oh Boy... Fit stick is your solution. We have 2 down here - but I suggest you buy your own and - hell, buy 2 - and laser levels, etc. There is one way to do this - the right way. Get all you bikes dialed in the same - or better yet - sell all your bikes and have E-Rich build you 2 - one for sunny pleasant Sundays and one for salt and sandy Saturdays. - Matt (I may have to email you or call direct on this one - it ain't rocket science)

[Climb01742]

matt, any and all help appreciated. what i don't know could fill an encyclopedia. a blank one, of course.

[zap]

Climb,

My Look Monoblade has a decal on the top tube indicating the BB position and markings every 5mm fore and aft. It doesn't look to bad in a high tech sort of way. The Look Monoblade was and still is the best bike (sorry Smiley), at least when it comes to adjustability. And you gotta love that full carbon fork with external aero steerer tube.