DIY stage 8: Continuous improvements...
- Thread starter daniel.weck
- Start date
I don't know much about these Garmin devices, other than they have a good reputation. They seem ideal for hiking / cycling: sturdy, low power consumption, usable in outdoor conditions (screen visibility, waterproof), etc. A friend of mine has one and I saw him buying maps for when he did new mountain walks...so I suppose it's quite easy to use.
I wouldn't touch the cheap chinese multi-function devices (last link) with a barge pole, unless they use a proven SiRF Star III chip (which I doubt).
Yeah...these things don't come cheap, I hope he will be generous this year !!
Hi Bob, I'm not sure I understand your question...Could you clarify please ?
Regards, Dan
A few more geeky facts:
The Meter-Development at highest 6th gear on my stock Brompton M6R+ is 6.7m.
That's with a 50T chainring, 13/15 derailleur sprockets, SRAM/SACHS 3-gear hub (and 170mm cranks).
(from Sheldon Brown's Bicycle Gear Calculator )
From the same webpage, I can immediately calculate that 120rpm at the pedal corresponds to 48.3 km/h.
Some simple arithmetics can be used to find-out the rpm value for 50km/h:
50km/h = 50,000 m / 60 mn => (50,000 m / 6.7m) / 60 mn [rpm] ==> 124.3rpm
I'm not a strong cyclist, so of course those values are achievable only going downhill.
Cheers, Dan
The Meter-Development at highest 6th gear on my stock Brompton M6R+ is 6.7m.
That's with a 50T chainring, 13/15 derailleur sprockets, SRAM/SACHS 3-gear hub (and 170mm cranks).
(from Sheldon Brown's Bicycle Gear Calculator )
From the same webpage, I can immediately calculate that 120rpm at the pedal corresponds to 48.3 km/h.
Some simple arithmetics can be used to find-out the rpm value for 50km/h:
50km/h = 50,000 m / 60 mn => (50,000 m / 6.7m) / 60 mn [rpm] ==> 124.3rpm
I'm not a strong cyclist, so of course those values are achievable only going downhill.
Cheers, Dan
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Now I understand the crank-rpm figures better, it puts things in perspective. If I had the skills and tools, the Tongxin motor I have in stocks (36V 180W 190rpm 80mm) could be coupled to the crank via some reduction gear and with a freewheel interface...just like what has been done recently on pedelec.de (on a full-size bicycle). The main problem would be calibrating the controller so that the PAS (Pedal Assist Sensor) could be used smoothly. In the meantime, the throttle could be used for testing the setup...
- EDIT - video of the freewheeled crank:
YouTube - Tongxin als Kettenantrieb 3
- EDIT - video of the freewheeled crank:
YouTube - Tongxin als Kettenantrieb 3
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Wow ! Some guy in Germany built his own carbon-fiber layered bicycle frame with a custom-made Tongxin crank adapter. Awesome work, very lightweight e-bike:
Tongxin Kettenantrieb am Carbonrad - Pedelec-Forum
!
Another calculation tool, this time from Ben @ Kinetics:
A few more geeky facts:
The Meter-Development at highest 6th gear on my stock Brompton M6R+ is 6.7m.
That's with a 50T chainring, 13/15 derailleur sprockets, SRAM/SACHS 3-gear hub (and 170mm cranks).
(from Sheldon Brown's Bicycle Gear Calculator )
From the same webpage, I can immediately calculate that 120rpm at the pedal corresponds to 48.3 km/h.
Some simple arithmetics can be used to find-out the rpm value for 50km/h:
50km/h = 50,000 m / 60 mn => (50,000 m / 6.7m) / 60 mn [rpm] ==> 124.3rpm
Here's a place to source Bottom Bracket / chainring freewheels:
Sick Bike Parts LLC - Performance Parts for Your Motorized Bicycle
There is not much choice unfortunately (note that 36 holes are currently out-of-stock):
Sun CR18 16 x 1 3/8 / 349 Side Wall Rim 36 Hole
Sun CR18 16 x 1 3/8 / 349 ABT Side Wall Rim
I used to be a rave organiser and have been using GPS since the early 2000s for various purposes
(for the benefit of any coppers on this forum I knocked this activity on the head over 3 years ago as things were getting out of hand) I've had one of these on my bike for about a year now - I think you have to buy the handlebar mount as an extra though. Its good for monitoring tracks and speed but not a street-level satnav if thats what you want.
PS: I forgot to add that the way I use my GPS terminal is much more the "old skool" way by logging grid references / waypoints of noteworthy areas and either using electronic or paper OS maps to look more closely at them - in other words I am investigating a place where I already have a rough idea where I am going (or saving a location for later reference) rather than using it as the main method of navigation to an unfamiliar area. For this I tend to use real maps - I don't want to be squinting a pokey little screen whilst riding, that way a nasty prang could well happen
Its a bit like how most of use were quite correctly taught basic arithmetic first before being allowed to use pocket calculators.
Its a bit like how most of use were quite correctly taught basic arithmetic first before being allowed to use pocket calculators.
This SIRF III device looks like a perfect companion for logging GPS tracks (working off standard AAA batteries is a good thing, IMO):I used to be a rave organiser and have been using GPS since the early 2000s for various purposes
I've had one of these on my bike for about a year now - I think you have to buy the handlebar mount as an extra though. Its good for monitoring tracks and speed but not a street-level satnav if thats what you want.
Amod AGL3080 GPS Photo Tracker Mac and PC: Amazon.co.uk: Electronics & Photo
Amazon.com: AGL3080: Amod AGL3080 GPS Data Logger (SiRF III Driverless 128MB Push to Log) (Windows and Mac Image Software included): Electronics
The Holux GPSport 245 gets good reviews:
Holux GPSport 245 review -- NaviGadget
Review - Holux GPSport 245 — Vancruisers.ca - Vancouver Cruiser Calendar, Vancouver Cruiser Rides and more!
Holux GPSport 245 Review :: chinamtb
...and its firmware is updated:
HOLUX - The Pro Name in GPS
Holux GPSport 245 review -- NaviGadget
Review - Holux GPSport 245 — Vancruisers.ca - Vancouver Cruiser Calendar, Vancouver Cruiser Rides and more!
Holux GPSport 245 Review :: chinamtb
...and its firmware is updated:
HOLUX - The Pro Name in GPS
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The Q-Starz BT-Q1000P-F unit is both a pocketable standalone GPS tracker and a bluetooth-enabled receiver. Its high sensitivity means that it's ideal for hiking/cycling.
http://www.qstarz.com/Products/GPS Products/BT-Q1000P-F.htm
http://www.qstarz.com/Products/GPS Products/BT-Q1000P-F.htm
Dan can I just check I've understood your throttle and pedelec set up.
You can run without pedelec attached and just use throttle on its' own, or you can install pedelec as well. With pedelec installed you can;
1. Use throttle as normal, with or without pedalling at any cadence.
2. Leave throttle alone and use the 3 position switch to choose max level of power input, with the actual power up to the max chosen being determined by cadence.
3. At any time you can over ride the pedelec system by using the throttle.
If you do over ride the pedelec system by applying the throttle (you gave example of shifting hub gear requires backing off pedals causing pedelec to stop and then restart which is not what you want when riding up hill!) does it also over ride the 3 position switch as well and just operate as if the there is no pedelec system at all.
Oh and thanks for BBB ergo grip idea I had some in the shed and replaced the Ergons I had on previously. Much better
You can run without pedelec attached and just use throttle on its' own, or you can install pedelec as well. With pedelec installed you can;
1. Use throttle as normal, with or without pedalling at any cadence.
2. Leave throttle alone and use the 3 position switch to choose max level of power input, with the actual power up to the max chosen being determined by cadence.
3. At any time you can over ride the pedelec system by using the throttle.
If you do over ride the pedelec system by applying the throttle (you gave example of shifting hub gear requires backing off pedals causing pedelec to stop and then restart which is not what you want when riding up hill!) does it also over ride the 3 position switch as well and just operate as if the there is no pedelec system at all.
Oh and thanks for BBB ergo grip idea I had some in the shed and replaced the Ergons I had on previously. Much better
Not exactly. Here's how it works:
(1) 3 "levels of assistance":
This feature is available at all times, whether throttle or crank sensor is used to control the ride speed. In the real-world, this translates into limiting the maximum speed that is achievable with each of the 3 levels of assistance.
The provided 3-stage thumb-switch is a selector for predefined speed limits, which values are specified in the controller firmware settings as percentages of the maximum power output (these thresholds can be configured using special PC software and a data cable between a USB port and the controller). The default fractional values are 50% 75% 100% but they give the wrong impression because the relationship with the perceived assistance is not linear.
The first level is only good for walking along the bike, or for cycling amongst pedestrians. I use the second level when climbing a serious hill (as the top speed cannot be reached anyway) or when riding side-by-side with slow-moving traffic. The third setting is obviously the most used one. In all 3 cases, the torque is the same so any level of assistance can be used to start from a standstill (as opposed to how mechanical gears work to translate leg power onto the road).
(2) Pedal Assist Sensor
This is a basic "pedelec" feature, because it doesn't measure the torque applied to the crank whilst pedaling, it only picks-up the crank's revolution rate. Assistance is turned on as soon as a certain rotational speed is reached, and it increases gradually and proportionally to the cadence.
The steeper the hill you want to climb, the higher the cadence you need (i.e. pedaling fast results in more power being fed to the hub motor). This contrasts with the throttle mode, whereby cycling at low cadence is possible, uphill or against the wind.
(3) Throttle
With this mode, one can manually fine-tune the assistance within the range of the currently selected assistance (out of the 3 predefined levels). Once activated, the throttle control overrides the PAS signal (Pedal Assist Sensor).
As it turns-out, riding with throttle is sub-optimal because of the mental effort and physical distraction required to "get it right", i.e. to strike the right balance between pedaling effort / choice of mechanical gear / suggested power output. I find it much easier to adjust my cadence to suit the PAS mode, as it's pretty much like a regular cycling pattern.
Furthermore, holding the throttle (thumb or handle) for more than a mile is not comfortable anyway. However, the throttle is very useful to kick-start the bike from a standstill, especially when one needs to quickly get out of the way at a junction with incoming traffic.
To conclude, I like to have both the PAS and throttle control at my disposal, in fact I think that they are indispensable. Whether I use one or the other, I find that listening to the motor's noise helps me determining the ideal human/assist ratio (the more silent Tongxin might be problematic
). Accurate feedback could be obtained from a watt-meter (Watts Up, Cycle Analyst, Turnigy, etc.), as the readings provide live information about power consumption / battery draw.One note about riding steep hills: when I climb a stretch of road with assistance, I never stand on the pedals with a high gear (low cadence), because it produces uneven power surges to the crank and wheels. Instead, I remain seated with a low gear (higher cadence) and I apply constant torque through each pedal revolution (down and up strokes that activate opposed leg muscle groups), so that the motor delivers a constant amount of assistance for a given hill gradient. I consider this good practice, because when I don't follow it, I can hear the motor struggling to operate correctly.
Final note: a crank torque sensor would obviously offer a much better cycling experience, as there would be a direct connection between the rider's intent and the delivered assistance. This, coupled with a tilt sensor (mercury accelerometer, like on the Wii console or iPhone), would create a very natural pedelec feel: an e-bike that reacts instantly to the environment, anticipating our every moves
Cheers, Dan
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You're welcome.
The missing riding mode on my bike at the moment is "no assistance": sometimes I don't want the motor to be turned on at all, for example when going downhill or when I want to remind myself how much effort is actually required to cycle "on my own"
I do not have a master switch, so the PAS signal always kicks-in...Cheers, Daniel
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