Does it really matter if my stem doesn’t block the hub?

Question

6’3” tall Bianchi via nirone c2c Alu carb 2010 bike.

I got hit by a car and am just rebuilding this bike so I can ride (the other one was totaled). The 120mm stem on it made the steering very skittish. I had a spare 130mm stem so I installed it in place of the 120 and it makes the steering more stable.

Nine years ago I cut the steerer tube down leaving x2 1cm spacers under the stem. After eight months off the bike post-accident I’m not as flexible a rider as I once was and would like to raise the bars but I don’t trust those steerer extension gadgets (I’m a big guy and I don’t need more time with the doctors!), so I fitted a 130mm stem. The steering is more stable and my long arms feel ok with the reach. However, I can see 1cm of my front hub while riding in this new position, does that really matter so much? The plum line from knee to pedal spindle is bang on.

I tried flipping the old 120mm stem up, but it was still skittish though. I can’t yet find a replacement suited Bianchi fork that hasn’t been cut either.

So is it really so important to have my position on the bike such that the handlebars are block my view the hub or is the comfort and stability of my current position more important than the "blocked front hub view rule of thumb"? Thoughts?

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Thanks for helping me :)

Im just a Mamil cyclist.

I’ve done some endurance stuff including trans America race and stuff but I’ll leave the wind tunnels to the TDF gang this year I think lol!

This bike is just for local rides to get back in the saddle after getting hit so I no longer have to risk my endurance bike to drivers around here :)

Answer 1

No, it doesn't matter. Riders have different body weight distributions, degrees of upper body strength, body proportions, and sets of priorities for their hunched-over versus upright positioning, even within competitive disciplines. Bikes have different front end geometries. Your firsthand judgments of the comfort and control effects of the change you made are worth listening to. There is always a next level of analysis that could happen that might reveal new information, i.e. what would a wind tunnel say about it, or an individual performance and comfort study over various distances and times with different fits, but if what you have appears functional it probably is.

The "you shouldn't be able to see the hub" rule belongs in the past with the myopic attitudes that gave rise to it.

Answer 2

The plum line from knee to pedal spindle is bang on.

This is a rule of thumb that originated in an era when we were a lot less empirically-minded. The notion that your stem should just block the front hub is another such rule of thumb. Funny enough, the rule that your max HR is 220 minus your age is an empirically-based rule of thumb - and really it should be described as the average max HR for a given age is 220 - age.

Rules of thumb may be correct or close to correct for the average cyclist. But they may not be exactly correct for you. For example, the average person my age should have a max HR of 178. I have observed 187 bpm during ramp tests, which means my actual max HR is probably a bit higher. Either way, that's a prediction error of at least 9 bpm.

Back to the original question, I personally prefer a much more forward saddle position than average. On the hoods, I can just see my front hub. The OP should make of this what they will. The OP also sounds like they are a bit uncertain about their bike fit. This is pretty normal, and this is also a good time to try to find a good bike fitter.

Bike fits given in the store are not what I'm talking about. Sales staff can get you very roughly in the right position, using gross rules of thumb like knee over pedal spindle. However, as I and others have discussed, we all vary a lot in our specific dimensions and preferences. Thus, serious cyclists probably benefit from seeking a good bike fitter. Moreover, our bodies and preferences change over time, so you so often have to repeat the fit sessions. It's true that this can be expensive, but if you are serious about cycling, I feel that it is a good investment - if nothing else, to be comfortable on the bike.

Answer 3

You have to consider the point of a bike fit (whether that's a professional fit or DIY trial and error). The goals are to have an efficient, ergonomic, and safe riding position or positions. The balance of those goals may change with what you're doing, but in terms of what you can see, the only thing that matters is the road - where you're going and where you need to look out for hazards. Arbitrarily saying that if you look in a direction you shouldn't be looking anyway, certain parts should line up, is a spurious constraint.

The person or people who proposed and popularised this view probably found it to be rule of thumb that worked for their bodies, in their disciplines, on the frames they were using at the time. But there's no direct physical reason behind it.

This reinforces points made in other answers, but from a different direction.