Sorry if this isn’t the right space, but I’m not having much luck on Reddit or another forum I frequent. I’m switching to a one piece road bar and hoping to keep my fit as close as possible. Just looking for a second set of eyes on this to make sure I’m not missing something.
Bike: Cannondale SSE4 54cm
Current setup: 100mm/-6 deg stem. Bars are 380 wide with 64 reach. Bike head tube 71.2. 35mm of spacers under stem with ~7cm of spacers above the stem.
Option 1: Tavelo Avro 380/90mm/-10 deg. These have 77mm reach. Would mount to the top of the steerer tube, so about 40-42mm of spacers. Math tells me about 3-5mm increase in both reach and drop.
Option 2: EXS Aerover 380/100mm/-10deg. These have 70mm reach. Would mount to the top of the steerer tube, so about 40-42mm of spacers. Math tells me about 6-7mm increase in reach, with a 2-4mm in drop.
The handlebar drop is all within 4mm of all three bars, so I’m not concerned there - I rarely ride in them sans a few sprints on a weekly group ride. Am I right that the Tavelo would get me closest to my current setup with the added benefit of a less cramped bar/hood transition area? And while the hoods will be within a few mm, I get the tops will be 10mm closer. I can’t imagine this would have a huge affect on handling at all, and really only be noticeable (if at all) while riding with hands on the tops? Thanks!
Jokes aside, even if it were mms you meant, that’s still a lot of spacers. Rule of thumb I’ve heard passed around is no more than 30mm on carbon steerers, but I’ve never seen it written anywhere.
Here’s how I compare stack and reach numbers to work out what stem/spacer combination I’d need when buying a new bike. Feel free to download a copy and stick your own comparison numbers in there if that helps (it’s read-only and the numbers in the sheet aren’t even mine - I think that must be the bikes that some other forum member was looking at when I decided to make a version of it available on google drive).
It just plots the XY of the centre of the handlebars at the stem clamp - I decided that since bar reach can be affected so much by how they’re rotated and where you put the shifter clamps I’d just guesstimate that part of the equation in my head when comparing different types of handlebars.
Put your current fit in the top line (row 5), then edit/replace/add as many other options as you like from Row 7 onwards. You just need to fill in the first two sections to get handlebar XY (blue/purple and orange). The yellow columns will tell you how different that row would be from your reference measurements.
Headset Cap is the mandatory spacer / bearing cover (if this isn’t already accounted for in the manufacturer’s geometry numbers).
Stem Stack is the height of the clamping area of the stem (this finds the midpoint of that)
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One disclaimer: a bike fitter told me I oversimplified some of the trigonometry somewhere in my formulas. I’ve never been able to find any shortcomings with the data it returns though, and I’ve bought several new bikes sight-unseen based off of fit numbers generated by this spreadsheet, so I trust it completely but just feel the need to say that to anyone else I share it with!
As far as I can tell, it’s just that I did it like a carpenter rather than a scientist - I used comparative angles where I think a good fitter does all their angles with reference to the same zero points (so I think I’m doing math on lots of little triangles where a scientist would do everything in reference to the absolute zero point).
I have a very simple excel sheet that does the same thing and just as a double check on yours mine comes out to within .01mm of yours so I think your math is good.
One note: it might make sense to add bar reach to it since that tends to vary pretty frequently.
Ape hangers, Harley Davidson style.. Yes, mm. Its a curse of body shape- kyphosis mixed with ME/CFS makes for a unique fit. The bike comes with nearly 70mm of spacers and Cannondale says it’s perfectly safe, so I have to think 35-40 is fine.