waynesworld

I don't understand much about bike geometry, and was wondering if someone who does could compare these two bikes and give me feedback. The first is a 2011 BMC Streetracer, which I own in 57 cm size:

https://www.bmc-racing.com/int-en/bik.../standard.html

The second is a Cannondale Synapse. I'd guess a 56 would probably fit me (I'm 5'11", with a cycling inseam of, I think 34. Pants inseam 32. I wear a 34/35 sleeve length dress shirt.):

https://www.cannondale.com/2013/bikes...mpact-crankset


Basically, I'm wondering if anything about the Synapse geometry makes it a more 'relaxed' bike than the Streetracer. I love the BMC, but I get neck pain after a while. I've tried different bars and stem, which helped, but I'm still not there. I'm considering an even higher stem, but wondering if I just need a new bike. Of course I need to ride more, get in better shape, and HTFU, but when I ride my Kona Jake I don't seem to have this problem. TIA for any help.

valygrl

Look at stack and reach. Stack describes how tall it is, reach describes how long it is, when measuring from the bottom bracket - so with the assumption that your saddle position is adjusted to be the same relative to the BB. There's some good articles on slowtwitch.com explaining the concept.

From your geometry charts:
BMC: stack 574 reach 395
Cdale: stack 580 reach 387

You would describe the Synapse as more relaxed than the BMC.

The Cannondale is 6mm taller and 8mm shorter, if you put the same spacers, stem & bars on it. If you already have a super short upwards-pointing stem and a huge stack of spacers, this frame might help a little, but the two bikes are within a CM of each other in both directions, so unless you are at an adjustment limit on the current bike, it's a lot of $ to pay compared with getting a higher stem and maybe some shorter-reach bars.

In any case, a good professional fit might be the place to start - I would definitely invest in a fit before a frame, or the chances of ending up with a second bike that doesn't fit are non-zero.

Bacciagalupe

I'd start by getting a real bike fit.

Buying a whole new bike, when you don't know what's causing the problem, is not a real solution.

Looigi

Correct. The numbers don't lie. The difference is less than a 1cm spacer and less than the available increments in stem length. The fits on these two frames can be made to be functionally identical as long as your not exceeding reasonable limits.

waynesworld

Thank you. I've been trying to understand stack and reach. That helps.

waynesworld

Thank you.

waynesworld

Thanks. I'm trying to avoid paying $200 or so for that if I can.

mac75

Your trying to avoid spending $200 on a fit, but your purchasing bars, stems, and now even considering a new bike?

The fitting was absolutely the best money I ever spent on my bike. I went from being in pain at 25-30 miles, to immediately being able to do 40-50 miles comfortably. ( exhausted, but not in pain)

Campag4life

mac is right. If you don't want to dig in and study geometry or experiment yourself by changing your position on your bike, then go to somebody that knows more. You have very average proportions OP which is a good thing for bike fit. Neck pain is a function of many things...bad posture...maybe your reach isn't enough (counter intuitive)...not enough setback...or too much which is overly closing your hip angle...bars either too high or too low.
Bad posture and riding position generally leads to neck pain and it generally can be traced to poor fit...many times not enough reach to the bars...cramped bikes are hard on the neck...arms in compression, pressure into the traps and neck.
The BMC you have isn't a bad size for you and a very good bike. I would experiment with your position before you consider another bike.

waynesworld

Thanks. I don't have a problem with experimenting, but I wanted opinions, since I don't know bike geometry well. Your suggestions give me some more ideas.

Campag4life

Thing I will leave you with wayne... When you see somebody who is fast and just looks right on a road bike, there is very little chance to it. Trial and error and a lot of hard work to dial the fit. I personally over many years have gone through countless fittings and experimentation and to this day, I still tweak my set up. 1 degree of saddle tilt...even changing the handlebar..ergonomics vary...position of the shifters...a spacer here or there...small changes can make a big difference. Also a camera doesn't lie. Get a trainer and take pictures of your position if you need more feedback.
Neck pain is perhaps the no.1 issue with a road bike for the simple reason that you are trying to cheat wind the best you can to maximize your speed. A very common newbie mistake and I still work on this decades later is proper pelvis rotation. A simple 'commitment' to proper position of the pelvis on the bike makes a road bike so much easier to ride in an aero position. Rotating your pelvis allows you to maintain good posture without high back flexion or a hump back which makes neck extension much more difficult which leads to neck pain. Satisfactory reach promotes better posture. Its hard to ride a short cockpit road bike properly with good posture. If you have to reach a bit more for your bars, you will be more inclined to rotate your pelvis properly forward.
See below.

waynesworld

Thanks so much! I really like the bars I switched to (some sort of Ritchey) but I do think I need to move the shifters just a hair higher. I'll work on the rest.

Thanks again for all of your help.

willawingwong

Try this bicycle geometry comparison tool out. You can see how they compare if you have most of the dimensions. https://gearinches.com/blog/misc/bike...try-comparator

waynesworld

Thanks!