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-   -   Copying Fit From My Old Bike (https://www.bikeforums.net/fitting-your-bike/1229646-copying-fit-my-old-bike.html)

Sojodave 05-03-21 08:52 AM

Copying Fit From My Old Bike
 
I built up a Roubaix 2017 Pro frame over the winter. I got a bike fit on my old bike and I'm trying to copy the same measurements onto the new bike. Both bikes have a Specialized Power Expert saddle and I copied length from the hoods to the front of the saddle to 31.5". I have the exact same handlebar height and yet the bikes feel completely different. On my old bike, I have no pressure on my hands and feel super comfortable. On the Roubaix, I feel more pressure on my hands and shoulders. I'm 6'4" and both frames are 61cm. The reach on my old bike is 411 and the Roubaix is 396. I added a 130 stem to the Roubaix to get the same measurement to the end of the stem because the old bike has a 120 stem. The only thing I can figure out is the stack in the Roubaix is longer than my old bike. The stack on the Roubaix is 650 and my old bike is 617. Can someone help me figure out how to compensate for the difference in stack?

Carbonfiberboy 05-03-21 09:28 AM

Do it this way: Start by using a long level (or a short one taped to a straight edge) to measure the horizontal distance between the saddle nose and the center of the bottom bracket on the old bike. Transfer that measurement to the new bike. Then measure saddle to hoods.

Iride01 05-03-21 10:23 AM

If the seat tube is a different angle from the other, then you may never feel quite the same on it. That's not to say you can't make it just as comfortable.

Sojodave 05-03-21 11:23 AM

I just checked and the seat angle for my original bike is 73 and the Roubaix is 73.5...pretty close. The head angle is exact for both at 74.

Iride01 05-03-21 02:47 PM

Are the handlebars the same reach and drop? And if you don't have your STI's at the same position or the bend profile of the handlebar is different, that might be putting you in a slightly different position that alters where you put your butt.

You are riding both and deciding about fit aren't you? Don't just sit on them and think bad of one.

Sojodave 05-04-21 09:18 AM

Update: I measured my bottom bracket to the saddle setback on my old bike and I moved my saddle on my new bike to match the setback. I had the saddle on my new bike all the way back on the rails and it now sets halfway on the rails. I went for a ride and there is noticeably more comfort. Being 6'4", I've always had my saddle back as far as it will go to accommodate my long torso.

tomato coupe 05-04-21 12:36 PM


Originally Posted by Carbonfiberboy (Post 22042395)
Do it this way: Start by using a long level (or a short one taped to a straight edge) to measure the horizontal distance between the saddle nose and the center of the bottom bracket on the old bike. Transfer that measurement to the new bike. Then measure saddle to hoods.

Easier to put the bike in a corner, with the back wheel against one wall. Measure from the wall to the saddle nose, and then from the wall to the bottom bracket, and subtract. Use the floor as reference for vertical measurements. No fussing with levels or plumb bobs.

Sojodave 05-05-21 03:49 PM


Originally Posted by tomato coupe (Post 22044478)
Easier to put the bike in a corner, with the back wheel against one wall. Measure from the wall to the saddle nose, and then from the wall to the bottom bracket, and subtract. Use the floor as a reference for vertical measurements. No fussing with levels or plumb bobs.

That is the method I used.


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