Front forks and more efficient bikes

[urstu]

I have been reading the threads on this forum for quite a while now and every now and then feel the need to have a go at what i consider is misleading information put out by some members.First if i was new to electric bikes i would assume by Fleccs information that suspension forks were a loadlof rubbish and a waste of time. Admittedly the forks on my Sprint are not up to much,but last month i purchased a focus city bike from Wiggle to which i have fitted my own motor kit with suspension forks.The ride transformation was amazing compared to my Torque and Sprint the comfort and handling superb.My point is Fleccs gives a lot of valuable advice but some of them are personnel views which should be taken with a pinch of salt.Second point a few weeks ago it was stated<not by Flecc as far as i know> that hub motors are more efficient than gear drives Please inform me has some great event taken place that i have missed what new and ground breaking product are we talking about.Until a few months ago the Giant range of bikes could not be beaten, climbing just about any hill because it drives through the bikes gears and that is on a 24v batt.I can only assume you were talking o f the new Forte and Forza with there uprated 250 watt motors ,and have a wider powerband, but nothing is free and must consume more juice ,plus a hub motor going up a steep hill cannot possibly stay within it's comfort zone ,and therefore must start to consume amps ,while a geared drive will not be as efficient through its drive but it will always be in the motors powerband if driven correctly.

[flecc]

Originally Posted by urstu

I have been reading the threads on this forum for quite a while now and every now and then feel the need to have a go at what i consider is misleading information put out by some members.First if i was new to electric bikes i would assume by Fleccs information that suspension forks were a load of rubbish and a waste of time.

I have never said this. What I have remarked on is the fact, not personal opinion, that suspension forks are much less efficient on a bicycle because they waste rider energy, and in some circumstances also waste motor energy. Of course, if you feel you know better than all the world's top cycle designers, so be it. I'm always pleased to receive criticism, but it should be based on what I've said, not what was imagined with different words used to add emphasis to the implication of rubbish.

Originally Posted by urstu

The ride transformation was amazing compared to my Torque and Sprint the comfort and handling superb.

Of course it was more comfortable and I have said as much in postings here. I have never argued that they aren't comfortable, and indeed I've posted several times that with front hub motors suspension forks are necessary for a comfortable ride. I've also clearly stated why, to cope with the high unsprung weight of the hub motor. But that fact on comfort does not make these forks efficient.

As for the superb handling, you must have been very lucky on that bike, and I hope it stays like that for you. In general, for weight reasons the implementation of cheap suspension forks on bikes is very poor compared with motor cycles. They can be initially good but then seize with use, those that don't seize often being very sloppy and giving poor handling. There are some very high price exceptions. That's been my experience, the experience of many in the trade, and something commented on by A to B Magazine. In this forum, the highly experienced Ian has also posted on the rare legitimate use of suspension on competitive mountain bikes, stating correctly that they have hardly any movement and are only there for the most extreme shocks. [/quote]

Originally Posted by urstu

Second point a few weeks ago it was stated<not by Flecc as far as i know> that hub motors are more efficient than gear drives Please inform me has some great event taken place that i have missed what new and ground breaking product are we talking about. Until a few months ago the Giant range of bikes could not be beaten, climbing just about any hill because it drives through the bikes gears and that is on a 24v batt.I can only assume you were talking of the new Forte and Forza with there uprated 250 watt motors ,and have a wider powerband, but nothing is free and must consume more juice ,plus a hub motor going up a steep hill cannot possibly stay within it's comfort zone ,and therefore must start to consume amps ,while a geared drive will not be as efficient through its drive but it will always be in the motors powerband if driven correctly.

First you say this was not said by me as far as you know, then you say that you assume I was talking about the Forte and Forza, which again indicates a somewhat muddled approach to your criticism. Let me put you wise.

I read just about everything in this forum, and have never seen another comment in this way. The only time I've said anything about this was in reference to my Q bike which for the first time was a hub motor bike which exceeded the efficiency of the Giant Lafree Twist. It did that by having a minimum of 14% more performance in any factor for a 9% higher consumption.

That's the correct way to judge efficiency. You've fallen into the common trap of not considering the performance given. That view would mean that only the smallest and lowest powered of anything would be efficient, making something like a Daihatsu 600cc car the most efficient, clearly a nonsense.

As far as I am aware, no commercially available hub motor can exceed the efficiency of a good bike equipped with the Panasonic geared motor system, but as I've shown, it is possible. What isn't possible, and I've never stated otherwise, is that a hub motor can beat any motor driving through gears, it can't, and the fact that the Q bike has done so against the Panasonic equipped bike is merely a statement that the latter isn't as good as it could be, while the former is.

What I have stated is that a Hall effect motor driving through the bicycle gears is a mistake, done just for convenience and economy. A motor covering the useful legal range of 5 mph to 15 mph with the legally required power phase-down from 13 mph is covering a band of 8 mph only. To cover that through 5 to 8 gears is ridiculous. Only the rider needs those multi gears, a Hall effect motor's power and torque band characteristics needing only two gears to cover that 8 mph band at optimum efficiency. Gears themselves lose efficiency, so volunteering more loss for an inadequate gain is foolish.

The optimum therefore is a motor driving though two automatic change gears and the rider with their gears suited to their use and conditions. Such a motor could be hub or driving a secondary chain.

In conclusion, I hope I've shown you that I have not posted any misleading information, but if you find some you do consider is misleading, please cut and paste it in a response and/or give the permalink to where I've posted it.

Thanks Urstu
.

[urstu]

Sorry i personally think you are splitting hairs an ordinary person coming to on to this site wants to know if decent!suspension forks make for a better bike,in my case 100% yes whether this will be so in 6 months time i will have to wait and see.On the subject of hub motors against geared bikes from memory i am pretty certain that it was someone else ,you had not posted much that week,the person stating we had gotten to a stage were hub motors were the way to go as they are now more efficiant,it was sometime around the discussions on the Nano motor,but i will now try, and find the discussion in the postings.

[flecc]

No, I'm not splitting hairs Urstu, just stating fact. Suspension forks do not make a better bike and you are wrong to say so, they make for a more comfortable bike which happens to suit you, since you are obviously unaware of the disadvantages.

What I do say is that suspension forks are necessary on a front hub motor bike if comfort is a priority.

If I posted that they do make a better bike I would immediately come under attack from the knowledgeable members of this forum for saying it.

Suspension for bikes was invented back in the 19th century, but in the following many decades when all the world cycled and few could afford a car, they knew too much about bikes to adopt it. Suspension finally gained ground from the early 1980s once most of the western world owned cars and no longer knew what made a good bike. In the markets where most people still cycled they still didn't adopt it for their own use, they just made it for westerners who knew no better.

It's up to you Urstu, have an open mind and learn more, or close it and stay stubbornly believing that what suits you is always the best.

[nigel]

I think on some electric bikes front suspension is needed powabykes and other heavy machines but it comes at a cost with ref overall weight i wonder how the torq might perform with suspension maybe take out some of those bumps.

[Ian]

Do suspension forks make a better bike. Yes, if the bike is to used for downhill mountain biking where the alternative would be a buckled wheel or frame and Yes if comfort at the expense of efficiency is the objective. In almost all other cases the answer has to be no for the following reasons.

Suspension absorbs energy from the riders pedalling effort. Observation of a person riding a bike with suspension will show the suspension expanding and contracting in time with the riders pedal thrusts, most of this energy being wasted in the damping mechanism. This is particularly true of rear suspension but also applies to a lesser extent to forks.

Suspension absorbs energy from road bumps, this is what its designed to do, but the energy lost in the damping has to come from somewhere and results in a loss of forward momentum.

Suspension adversely affects handling. This can be because of slop in the telescopic portion, or just the fact that a telescopic fork can never have the stiffness of a rigid fork. Another more serious handling issue is the change in geometry and resulting reduction in ground clearance when the forks compress under cornering forces, particularly when a bump is encountered at the same time. Properly designed mountain bikes take this into account but enthusiastic riders on lesser machines often come to grief after grounding a pedal. I speak from experience.

Suspension forks increase weight.


It's because of the above and other reasons that designers trying to achieve efficiency and performance never consider suspension forks and they are simply never seen on serious road bikes, even those used in long races where riders spend 40 hours a week or more in the saddle.

[coops]

Everyone has different preferences & often choose bikes & ebikes accordingly, like you said urstu 100% your bike is better, for you, with suspension. Comfort is one thing, but the facts about what make efficient bikes are there for all to see .

I find it very useful to learn here about firstly what makes a good bike and then how best to motorise it, to help see what to look for in an ebike for my own requirements.

In many cases, especially the last generation or two, I think people may be happily surprised to learn more about how different, and more rideable, most bikes used to be only 15-20 years ago .

[prState]

Originally Posted by Ian

Do suspension forks make a better bike. Yes, if the bike is to used for downhill mountain biking where the alternative would be a buckled wheel or frame

I was suddenly reminded of this (warning: bike crash)

[Ian]

Nice find prState. Seems some riders need more than sus forks to prevent bike failure. I couldn't tell exactly what broke but certainly the forks separated from the frame

[ITSPETEINIT]

I have had my Sprint for 10 weeks and 600 miles now and I can say it is pitched exactly where I need it: Gearing; Suspension; Weight; Range and Carrying Capacity.

I still struggle to crest some hills (Long ones with gradients of about 9% or 10%. Muscles are improving very gradually. So all was joy until I discovered there was a certain 'drag' when commencing to pedal without power. I meticulously checked that all revolving parts were revolving freely (both wheels: they even reversed their revolutions when the imbalance of weight reached the top of the wheel). There was no resistance in the crank bearings. The brakes were not rubbing in the slightest. So I put it down to the bike's weight and wheel base compared with a non-motorised road/touring cycle.
Now I've just read Flecc's commentary on Front Suspension and the 'drag' is clearly the bouncing effect of the downward pedal thrusts. All that effort to drive the front wheel into the tarmac. I think "Lock-out" forks could be a good investment at those times when one has no motor assistance.
However, it must also be happening when pedalling with the motor running which is not good news. Alright when pedalling is light (in my case all the time except on hills), I accept the inefficiency. BUT when giving the bike serious wellie on a serious hill is another matter - you can't lean down and lock out the forks even if you have that facility.
On balance I prefer to suffer the bounce than suffer the shaking.
Peter