Front suspension, is it really that inefficient?
 

Hi all,

I've been here a little while now, and one thing I've noticed is a lot of people comment that for road cycling, a rigid front fork is the best approach, and the most often cited reason has been efficiency.

On Wednesday I had a front basket bracket break on my main commuter ('09 Giant Boulder), so for the past couple of days I've been commuting on my mountain bike ('12 Giant Talon 29 ER 0). Both are actually hard-tail mountain bikes with front suspension, the difference is the one I've switched over to has the ability to lock the front suspension, basically turning the front fork rigid. The bike doesn't get any lighter, but the front fork now shouldn't be absorbing any energy. The other one has an adjustment for the hardness of suspension but can't be locked out completely.

I tried this Thursday afternoon and Friday morning on my commute. I didn't notice any additional power, but one thing I did notice is just how rough Brisbane roads are without suspension. I wound up getting fed up of it yesterday afternoon and after climbing the first major hill, reached down to open the front suspension back up again for a more comfortable trip.

Is it just me, my set-up, or is there something I'm missing?

Well, when I get out of the saddle to sprint, front suspension really soaks up my energy. Not good. But, if your suspension is not bobbing up and down, it isn't hurting anything.

Another option - most bikes have a 40/60 (F/R) weight distribution. That means you can usually run your front tire at its minimum inflation pressure and have the same rolling efficiency as your rear wheel. Detailed power measurements show this has no affect on rolling efficiency. Plus, your bike will have a lot more traction on rough roads or loose terrain. Just ask the mountain bikers or cyclocrossers.

Try putting 10-30% less air in your front tire than your rear. It will improve both the ride and the traction with no drawbacks.

Not missing anything. A rigid may be lighter. Also font sus is great for ruts and ice on the trails,

I like it stiff and responsive on the road, but obviously opinions differ.

if you find it necessary to have suspension on the roads you ride, there's a good chance it may actually be more efficient that way.

My personal opinion on suspension forks is that they suck for road riding and I don't like how they feel. I never enjoyed riding bikes with suspension forks ... My arms and legs make the best suspension. Bigger wider tires also help to soak up the bumps.

Ahh, that might be it then, I never stand on the pedals, I'm always sitting down. If it gets too steep for that, I get off.

I can see how they'd soak up the energy when standing up since you're basically putting your body weight in for them to operate, and in that situation, having the lock-out feature would mean the best of both worlds (suspension when you want it, but then you can turn it off if going into a sprint).

However I've never been that steady, and my bike is rather top-heavy, so I never stand on the pedals.

When I bought the Talon, it was suggested that I look into a commuter bike; the Seek 0, which had rigid forks, and at the time I wanted something for off-road. However, the question as to whether a rigid fork would be better on a commute has haunted me a little. By the sounds of things, I have my answer. :-)

A properly set front suspension really only effects efficiency for out of the saddle efforts. Even then the difference is greatly over-stated. The trick is most hybrids and light trail bikes have coil forks which have only minimal pre-load adjustment. If you're too heavy for the spring, it will be very inefficient and bouncy. If you're too light, they don't really do much, and they're effectively locked out.

The main drawback is that they're 2-3 lbs heavier than a standard fork. Personally, my next commuter bike will be a 29er with a decent suspension fork so I can take "shortcuts" on the way home.

I have an elastomer Suntour fork. I maxed out the preload and I don't think it moves much under normal pedaling, but it still takes harder impacts. I had a chance lately to ride a higher level and newer version of my bike and the plush Marzocci fork was the most notable difference. I almost think it would be worth it. Expensive forks have features like valves that open for bumps but not slow movement, to reduce pedaling losses. Like so https://www.sram.com/rockshox/techno...charger-damper

Out of the saddle I notice a difference, but not when seated. I like suspension forks. I even read that they are being considered for CX bikes in a recent article.

Indeed, I've been told the front forks on the Boulder are actually starting to wear out (she's done 11400 km since 2012 alone, probably close to 18000 km total) and I might need to look into replacing the front fork.

So there's an opportunity to swap it out for something different, if it's not too expensive. (I don't fancy spending much more than AU$400 on a fork for a bike that was $500 brand new in January 2010.)

Given my experiment the other day, I think I'll rule out the rigid forks, because feeling every bump in the road and having everything in the front basket shuddering didn't impress me at all. The thought is do I go one of the same, or do I go for something a little more up market. I guess I'll talk to the local bike shop and see what they can source.

The other option is of course, to retire the Boulder and either get a new commuter bike, or to go for something more optimised for touring and make the Talon my commuter. Again, I'll have to do some research. For sure there'll be front suspension, while the roads around here aren't what I'd call "bumpy", a velodrome they are not!

I think it varies with both fork and conditions. My dual suspension MTB has an air fork and on pavement I really notice a difference between locked and unlocked. My hardtail MTB commuter had a less noticeable difference between locked and unlocked, but the main reason for converting it to a steel rigid fork was weight.
If your commuting route resembles a blasted moonscape then suspension makes sense , as do fat tires. On smooth pavement suspension is mostly just weight and complexity.