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# The Smart Bike as a Home Fit Tool

Dan Empfield Mon Jun 15 2020

By waxing enthusiastic about smart bikes earlier over winter I stuck my neck out some. I touted the utility of these bikes as personal fit bikes, because of their ease and range of adjustability. They’re not the sorts of bikes a fitter would have in his studio, but each is a bike that you and I could use to tinker with our positions.
I decided to put my position where my mouth is, and constructed an experiment to see how this might actually work. I had a Wahoo KICKR Bike in my studio for a while, and I’ve had a Tacx NEO Bike for the whole indoor season. What I intended to measure was my road position, which pretty much is my gravel position. The only difference difference greater than a centimeter between the two is my drops position, which is shallower on my gravel bike because of the bars I’m now riding. (In fact, I like this position so much better, I’m probably going to put a gravel bar on the new road bike I’m building.)

The experiment was this: Let my stationary position find itself. Raise and lower the saddle by feel; same with setback; same with cockpit distance and so on. I omitted measuring anything on these indoor smart bikes I was riding, so that I wouldn’t bias the outcome. When I knew I was done tinkering, my intention was to measure them, and see if my indoor position informed my actual outdoor bikes. If there was a variance, which position would I favor for all my riding?
First, let me tell you what I measured (which fit coordinates). I’m using a pic of a Cervelo R5 to illustrate. I’m measuring:

Saddle height and setback: I’m using the same crank length on all bikes, 175mm, so, I can measure from the BB.
Cockpit distance: both BB to Web X/Y, and also saddle nose to Web X/Y, because if there’s a variance in BB to Web X/Y then it might be that my whole cockpit is just shifted fore or aft. And, really, what I'm measuring to in this case is just Web X: the horizontal distance from either the saddle nose or BB to the hood trough.
Handlebar elevation: I measure the difference in height between the top of the saddle and the top of that 31.8mm section right next to the stem on the handlebar.
What is Web X/Y? It’s where the web of your hand contacts the hoods, which is at that point (ideally) where the hood makes its abrupt upward turn. It’s the center of the radius of that turn. I measure it with a quick lace like, say, Lock Laces: an elastic shoelace with a lace lock. I place this around the hood, as pictured below, and measure to the centerline, between the two hoods. I add saddle setback to the BB-to-Web X total to get the overall cockpit distance.

The Smart Bike numbers are from the Tacx NEO Bike I’ve been riding. Here’s what I got.
First, the overall cockpit distance:
Saddle Nose to Web X
Road bike: 680mm
Gravel bike: 670mm
Smart bike: 675mm
My gravel bike is what I’ve been riding lately, when I ride outdoors. About a month ago I felt as if I needed to lengthen my cockpit on that bike, so I replaced a 110mm stem with a 120mm stem and it felt better for sure.
Last week I got around to measuring everything, and you see the results. I've got a cockpit distance of 670mm on the gravel bike, close to what I found I was riding on the Tacx NEO Bike. The outlier here is my road bike, which is a bit longer. I now must make a decision here. What am I going to do about this? One decision I’ve made is that I’m going to err toward a slightly shorter bike frame when I choose my new road frame. My current road frame has a frame reach of about 400mm, and I think I’ll move to something like 390mm or thereabouts.

BB to Web X
Road bike: 600mm
Gravel bike: 590mm
Smart bike: 590mm
There's a number of ways to measure this. Bear in mind that this is not HX I'm measuring, which is BB-to-handlebar clamp, and one typical way to do this is to use the SICI tool, pictured above. I'm measuring past the handlebar clamp and all the way out to the Web X, which is to those Lock Laces.
There again, the road bike is the outlier, slightly. Why? Mostly I think it’s because the road bike is set up for climbing. When I’m out of the saddle I like a longer BB-to-Web X. Almost everybody does. This is one reason the Wahoo KICKR Bike is a slightly better smart bike for dialing in your fit: It inclines. This allows you to choose your BB-to-Web X both while riding level and while riding uphill, especially out of the saddle. Because I don’t ride out of the saddle as much on my gravel bike, that bike is optimized for seated riding, as is my Tacx NEO Bike. This is the one difference that might remain between my road and gravel bike: I might go 10mm further out on my road bike just for out-of-the-saddle climbing.

Saddle Setback from BB
Road bike: 80mm
Gravel bike: 80mm
Smart bike: 85mm
This semi shocked me. I spend all this time on that Tacx NEO Bike riding level (no climbing), in structured training and in high-intensity group rides where cadence is relatively high (almost always between 85 and 95), and I was dead sure my saddle would be a bit pushed forward on the Tacx NEO Bike. Basically, I’ve been doing what amounts to crit riding on that bike, just, indoors. However, I’ve also been thinking about this little experiment of mine while doing that riding, make sure that my weight displacement, saddle-to-hands, was right. Of all my bikes my position on the Tacx NEO Bike feels best, but that’s largely because there’s only one thing I’m doing: Riding flat; riding for an hour; high cadence; no climbing; very little riding out of the saddle.

Handlebar Elevation from Saddle
Road bike: 105mm
Gravel bike: 85mm
Smart bike: 95mm
As you see, I migrated to a handlebar elevation on that Tacx NEO Bike that splits the difference between my two outdoor bikes. In retrospect, I probably just should ride my road bike with the bars slightly higher. When I get my next road bike (which is the next bike I’m getting, as my current bike is at least 8 years old), I’ll not require the frame stack to be as low as I originally had figured.

How This Informs My Road Bike Choices
My current road bike, a first-gen Cannondale SuperSix EVO, has a frame stack/reach of 577mm x 399mm. It’s got a -17° stem, 120mm long, and it’s got a single 10mm spacer above 5mm top cap.
I’ll probably go with a frame closer to 390mm worth of reach. I don’t think I can go higher than about 595mm of frame stack or I won’t be able to get low enough, and that’s if I ride the bike with a flat stem slammed atop a 5mm dust cover. I would probably ride a -17° stem on that bike. I could go with a -6° stem which, if also slammed, means I could go as low as 580mm or so of frame stack. Probably that 580mm to 595mm is a good workable range, lots of bikes in that range, and something between 390mm and 395mm is pretty good for a frame reach.
I feel pretty good about my experiment. I think my indoor cycling informed my outdoor bike positions, both the gravel bike (which needed a longer stem) and the road bike, where my indoor riding has convinced me my road bike position is 10mm or 15mm too low.

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