Chalo
100 TW
The energy lost to suspension damping has to come from somewhere. That's why most racing bicycles don't have suspension.
Hi All
- Thread starter outofsquare
- Start date
full-throttle
1 MW
Is that so :lol:Chalo said:
Are you saying mountain bikes are not for racing? What about cross country, down hill, slalom, 4-cross, slopestyle, enduro.. etc
Enlighten us then - if this energy wasn't lost in the damper, where will it go? Will it be somehow converted into forward motion. Will it help with traction? Will it delay fatigue?
Chalo
100 TW
full-throttle said:
We're not talking about a bike that will be used for racing on rough singletrack, but for regular transportation on paved streets. For that, unsuspended bikes are proven to be more efficient. Even on the formidable cobblestones of Paris-Roubaix, mechanical suspension has been tried and rejected. Do you think an economy car or an F1 racer needs as much suspension travel as a Baja 1000 racing truck?
My point was that tires inflated to modest pressures may cost some rolling resistance, but mechanical suspension dissipates energy even more directly. That's what it's designed to do, whereas rolling resistance in pneumatic tires is just a side effect.
Yes, energy stored in rolling surface irregularities can be restored to a vehicle's kinetic energy if it's not thrown away in suspension dampers. It's only very abrupt shocks, vibrations, and displacements that can't be recovered. Undulations, such as are common in paved surfaces, are mostly absorbed by suspension, but largely restored to an unsuspended vehicle by its elastic tires.
outofsquare
10 mW
All I can say its going to be my every day work bus come rain or shine, the roads I will be travelling on are all perfect bitumen roads, no billy goat tracks I have to maneuver around Lol, the bike I selected has got front suspension forks, I f I have to ride over a lame kangaroo or a wild feral alley cat I will lift my but so it does not absorb the shock 
but what has been really important to me is getting the right battery pack set up, and someone has brought to my attention that i really need a 36 volt pack to do my 30km round trip, not the 24 volt 15 ah battery pack I was going to use (well I already ordered the cells from Headway) so just going to order a few more to get the 36 volt pack I should use.
Cheers
Tom
but what has been really important to me is getting the right battery pack set up, and someone has brought to my attention that i really need a 36 volt pack to do my 30km round trip, not the 24 volt 15 ah battery pack I was going to use (well I already ordered the cells from Headway) so just going to order a few more to get the 36 volt pack I should use.Cheers
Tom
full-throttle
1 MW
What sort of increase in efficiency? 10%, 1% 0.001%?? You are missing the point - most people especially ebike users are happy to trade a miniscule decrease in efficiency for gain in comfort. If it wasn't a race would you ride Paris-Roubaix with or without suspension?Chalo said:
So.. what's the punchline? Tyres on a suspended bicycle are exactly the same as on an unsuspended one. The suspension doesn't react to small irregularities you're referring toChalo said:
outofsquare
10 mW
Excellent comments on suspension bikes, Im learning heaps from reading the replies, actually I have to be honest, would have liked a full ssupension frame if I could have afforded it, but my budget had been increased as it was, I wanted to spend the additonal coin in getting a good battery set up, the bike shop let me take a suspension bike for a whizz & I have to admit it was flippin nice, real nice, but then I asked what it cost & that closed the door on me, he gave me another to try which would have been in my budget, but it was awfull comapred to what I rode just before, the whole suspension set up just looked flimmsy & felt I dont know how to expail it squishy, so I just bought a know brand hard tail with front suspension forks, but I have to admit it would have been nice & given me some more scope on where I could have gone with it
I will wait until I finish my very first build & see how I enjoy the whole E bike thingy, but I think another build is looming in the not to far distance, I read a psot on a suspension frame build where they chopped the frame up & inbuilt a battery comaprtment into it, now that looks like a good intresting build for me, first have to learn how to put the battery pack together though Lol
Cheers all
Tom
I will wait until I finish my very first build & see how I enjoy the whole E bike thingy, but I think another build is looming in the not to far distance, I read a psot on a suspension frame build where they chopped the frame up & inbuilt a battery comaprtment into it, now that looks like a good intresting build for me, first have to learn how to put the battery pack together though Lol
Cheers all
Tom
Rodney64
100 kW
Keep an eye out in gumtree. Always plenty of second hand bikes going there.
full-throttle
1 MW
Good choice. Rear suspension doesn't make as much difference as the front.outofsquare said:
If you want an example of good, reliable setup have a read through my commuter's build. 20,000km on it and counting. Started as rigid, put front fork later on. Singlespeed 8)
The bill:
donor bike: $400
motor: $180
spokes: $60
rim: $60
decent tyres: $40
fork: $50
44t ring: $20
SS sprocket: $10
chain: $10
---------
total $830
controller was donated by voicecoils
BMS homemade
throttle $5
charger $20
cells free 8)
dogman dan
1 PW
In general, Chalo is right. Pedal bob eats up your pealing power alive. And nothing wags the tail as bad as a cheap wallmart full suspension bike, those bike shaped objects are quite floppy.
But a good FS bike can be a dream to ride. Screw the pedaling efficiency, that's why you put the motor on it. So what if your pedaling is just for show, keeping your ass from falling asleep, and a bit of light cardio exercise.
You don't set up a FS bike super cush for the street. Set it up fairly stiff, and you get a decent ride with only about a half inch of pedal bob if you do pedal hard. Yet when you hit a speed bump at 30 mph you didn't see in the dark, you still get several inches of great suspension travel. Super cush is for riding up the stone staircase up in the mountains.
Yeah, as for rain, riding through 6" puddles could be a problem. Though I've done it too with no problem, on my dirtbike after a big rain. I was refering to riding in moderate rain, with good fenders. Lots of hubmotors have functioned for quite some time with water inside them, eventually rust stops em. Oddly enough, the solution is to drill holes to let vapor out as steam if the climate is really wet. Waterproofing coatings on the inner parts are also advised. Connectors and controllers need to be kept dry somehow.
But a good FS bike can be a dream to ride. Screw the pedaling efficiency, that's why you put the motor on it. So what if your pedaling is just for show, keeping your ass from falling asleep, and a bit of light cardio exercise.
You don't set up a FS bike super cush for the street. Set it up fairly stiff, and you get a decent ride with only about a half inch of pedal bob if you do pedal hard. Yet when you hit a speed bump at 30 mph you didn't see in the dark, you still get several inches of great suspension travel. Super cush is for riding up the stone staircase up in the mountains.
Yeah, as for rain, riding through 6" puddles could be a problem. Though I've done it too with no problem, on my dirtbike after a big rain. I was refering to riding in moderate rain, with good fenders. Lots of hubmotors have functioned for quite some time with water inside them, eventually rust stops em. Oddly enough, the solution is to drill holes to let vapor out as steam if the climate is really wet. Waterproofing coatings on the inner parts are also advised. Connectors and controllers need to be kept dry somehow.
outofsquare
10 mW
Yeah definetley going to go Gumtree searching if Im going to try a full suspensions bike build later, nice practical bike Full Throttle, its pretty much what I will end up with except for front suspension & mine will be mid mount, all the parts should be here early Jan, plan to get it built before I start work on the 31st Jan if all goes according to plan. well it has to be done before I start work again as I have sold my car & shes gone in a week, im looking forward not to having to go to the servo and handing over those redbacks anymore every week, if I calc it right I wont even be charging my batteries up at home (oh well not for the first charge) checked & the storeroom has a GPO just waiting for me
Cheers All
Tom
Cheers All
Tom
Chalo
100 TW
full-throttle said:So.. what's the punchline? Tyres on a suspended bicycle are exactly the same as on an unsuspended one. The suspension doesn't react to small irregularities you're referring toChalo said:
Sure it does. Stack a suspension on top of a tire and the one that moves more will be the one that's softer at that moment and mechanical state. Boingy bikes get less action and benefit from their tires than rigid bikes (which is still a lot more than nothing at all).
The action of a pneumatic tire is mostly elastic and only slightly damped by the rubber, so much of the energy stored can be released as it relaxes. Mechanical suspension is designed to turn that same energy into heat at a much higher proportion.
When surfaces are bad and speeds are high, a tire's travel is too short, its spring rate too high, and its damping inadequate. These things are all addressed, to some degree, by lowering tire pressure and using fatter tires if possible. There is only so much you can do, but options are getting better all the time with 26x5" and 29x3" capable bikes and tires now available.
When surfaces are good and smooth, mechanical suspension throws away a lot of energy that could be used to propel the bike, or to keep it rolling. It also introduces porpoising, bobbing, and dive that all impair a bike's controllability. At those times, it helps to have shorter travel, higher spring rate, and lower damping rate. That's why some of the best suspension forks have on-demand lockout. But suspension that is not equipped with a lockout function is a lot harder to modify for good surface conditions like streets than it is to lower a tire's pressure or switch to a bigger tire for rough conditions.
These drawbacks are somewhat less important for e-bikes than they are for pedal bikes-- pedal bob is nonexistent when you're not pedaling, and there is not such a firm upper limit on how much power is available to you-- but when power is in limited supply, higher system efficiency means you get to do more with it.
Pedal bike designers have been chipping away at the efficiency problem for over 150 years, with only the same amount of power available now as when they started out. So the proven solutions have become very good, and radical changes should be regarded as inferior until definitely proven otherwise. There is no other machine, outside of maybe a violin or something along those lines, that is less likely to be improved by a novel development.
onlineaddy
1 W
Newbie question: you can't use the gears on your bike with a hub motor?
Chalo
100 TW
onlineaddy said:
Yes, you can, but a hub motor applies more constraints than a typical modern bike wheel. It most likely uses a freewheel instead of a cassette, for one thing, and that means 8 and 9 speed rear gearing are difficult to implement and 10 & 11 speed can't be used at all. So, for instance, if your donor bike has 3 x 8 speed gearing, it will be easiest to change out to a 6 or 7 speed rear shifter and matching freewheel at the time of your hub motor conversion.
Many rear hub motors have such narrow flange spacing that they can only build into a normally strong wheel if they are built up symmetrically-- which might not allow enough room for even a narrow 5-speed freewheel.
Anyway, most of the rear hub motors used by participants in this forum have a multi-speed derailleur drivetrain.
Chalo
winkinatcha
10 kW
haha Full-throttle... Free Controller and Free battery... awesome score there, considering that would be another $600 ish to add to the build if'n ya had to buy em...
Nice on the 10k + kms Credit to your bike mechanicing knowledge n application
Joe
Nice on the 10k + kms Credit to your bike mechanicing knowledge n application
Joe
full-throttle
1 MW
lol Do you have any scientific evidence to prove that? Not with a well set up suspension and good pedalling technique. Pedal bob is a distant past with modern designs.Chalo said:
I see you have some kind of religious hate for suspension and disc brakes. It's ok - some believe vinyl sounds better than CD, film cameras are better than digital and it's wrong to have sex before marriage. Fine. More fun for the rest of us :lol:
onlineaddy
1 W
Chalo said:
My bike actually currently has 3x7 gearing. However, I was planning on switching out the integrated shifter/brake into standalone shifter so I can use the e-brakes from the kit. The only rear shifter available is at least 8 speeds. Won't that shifter still work with a 7-speed freewheel if I just don't use the extra gear on the shifter?
john7700
100 W
onlineaddy said:
Unless you are doing a lot of big hills or a LOT of stop and go or are building a very high powered rig, I would just forget about regen. It really isn't that useful for what you get back in energy vs. the added complexity. It is effective as a break IF you are regularly riding in conditions that merit it. Otherwise, skip regen and E-break, keep the bike much more simple and not have to switch out your shifters.
Sorry to hijack OP. Sounds like you will produce a nice build with your skill set. Looking forward to seeing the outcome.
onlineaddy
1 W
john7700 said:
I'm not doing it for the regen; it's the extra safety measure provided by the e-brakes that I'm interested in. If the 8-speed shifter works with the rest of the 7-speed system (rear derailleur, freewheel), then I don't mind the extra unused gear marking on the shifter.
Yes, OP, if you'd like us to take this discussion off this post, I'd be more than happy to.
GrayKard
10 kW
onlineaddy said:
Well, he wanted to use the thread to introduce himself, which he did. So I'm thinking he's through with it. :wink:
7 and 8 speed freewheels have slightly different spacing usually. If the 8 speed shifter is indexed it may not work smoothly in all 7 gears (easy enough to limit it to the 7 though). If its a friction shifter, which is unlikely, it will work fine.
Here's a 7 speed twist shifter: http://www.niagaracycle.com/product_info.php?products_id=418256
Here's a 7 speed thumb shifter: http://www.niagaracycle.com/product_info.php?products_id=806091
And a 7 speed trigger shifter: http://www.niagaracycle.com/product_info.php?products_id=449735
They have lots more too.
Gary
Chalo
100 TW
onlineaddy said:
8- and 7-speed systems are incompatible; the spacing between gears is different, not just the number of them.
I think e-braking makes most e-bikes substantially less safe than normal mechanical brakes only. Regular brakes won't tear your dropouts or fork tips open and remove a wheel from your bike while you're moving.
Motor torque at the axle is already tough to manage with bicycle components. Reversing torque steps up the stresses and risks to a higher level.
Chalo
100 TW
full-throttle said:
Only the fact that hydraulic dampers are being moved, and their design intent is to convert kinetic energy into heat. You could convince yourself that dissipating your kinetic energy into hydraulic dampers doesn't slow you down, but you'd be delusional.
Mechanical suspension is for vehicles that have an overabundance of motor power to squander.
full-throttle
1 MW
So, you don't know how much energy is 'wasted'
Alright, let me ask what kind of suspension have you actually tried? Brand, make and settings. Because I can tell you either never tried one, tried one from a dept store or did not set it up properly.
Will you agree that at speed aerodynamics is the biggest drag? So why don't you recommend changing riding position instead? Perhaps switch to drop bars, tubular tyres, disc wheels, wear a lycra suit, teardrop helmet, get rid of gears, brakes and freewheel.
The fastest upright bicycle:
Is it practical? NO
Is it comfortable? NO
Alright, let me ask what kind of suspension have you actually tried? Brand, make and settings. Because I can tell you either never tried one, tried one from a dept store or did not set it up properly.
Will you agree that at speed aerodynamics is the biggest drag? So why don't you recommend changing riding position instead? Perhaps switch to drop bars, tubular tyres, disc wheels, wear a lycra suit, teardrop helmet, get rid of gears, brakes and freewheel.
The fastest upright bicycle:
Is it practical? NO
Is it comfortable? NO
onlineaddy
1 W
GrayKard said:
Thanks, Gary, for the link to the Shimano SL-M310. I did not find the Acera (lowest end, I believe) when I searched online. I did find the Alivio (one grade up), but that is the 8 speed I was writing about.
onlineaddy
1 W
Chalo said:
I'd like to be able to stop safely in an emergency though, Chalo. Is torque stress an issue for a mild-powered (1000w) rear-hub Mac motor? If so, would you recommend installing a torque arm/plate to alleviate the concern?
biohazardman
100 kW
Toque arms are a good idea, safety feature, for 500w and above rear motors. Jumping into the full suspension bike controversy I have, four of them, the three older units bob up and down when you pedal, I hate it, and a newer Giant. My Giant Trance3 is a completely different story the Maestro suspension is great and the pedal bob is not even noticed unless I stand on the pedals and really try to get it to bob up and down. I have held off on my latest build because, I am spoiled and don't like the way the donor bikes handle. You can put a suspension post on your hardtail and add some nice cushy tires to smooth it out a bit though. Although a rear hub will likely limit your gearing to 5-7 on the freewheel don't worry I run my 9 speed trigger shifter with a 7 speed freewheel and it werqs fine after some tuning. I hit 5 gears perfect and do a double click for 1 more I don't use the granny gear but it looks good there anyway. ;^) Good luck on your build and get a good parts your life will depend on them.
