Why two chainrings?? Well, a couple of reasons.
I have played around with 3 different sized chainrings so far but only one at a time can be fitted onto the drive from the Bafang motor. I am seeking the ideal size giving an high enough top gear so 30kph can be pedalled easily but also with a low enough bottom gear to allow hill climbing with spin to stop the Bafang lugging and getting hot. Probably not a concern in winter in Tasmania but necessary in the summer when hill climbing in 30°C plus temps.
Phil (the amazing E-Bike fettler) of Carlton designed a fitting that supports 2 chainrings. I felt that this fitting may assist with getting the ideal ratios. So Phil made me a 45 tooth / 38 tooth double chainring. 45 tooth – that’s an odd number in more ways than one. Apparently it comes from the Mountain Bike scene and is one tough chainring.
On Saturday I mounted the fitting and did a driveway test. “That looks wrong” I thought. Thinking some more; “Ah yes, Phil did warn me to mount them with the small ring on the inside. I see why now!”.
So off the chainrings came and back on they went, swapped around. I set off for a test ride. There is no derailleur as such. The idea is to pull the chain tube to direct the chain. It worked OK to move the chain from high to low gear (large ring to small ring). The attempt to move the other way resulted finding out the tube was worn, it broke, it ran along getting stuck between chain and chainring. Bugger!!
On Sunday I made a new tube from a piece of hosepipe I found in the garden shed. (Shhh! Don’t tell Sue.)
Further testing ensued and the system works but it is clumsy and I suspect changing the front chainring will mainly be done by hand. Note to self : pack some covid gloves to keep from getting oily. I will do further testing before heading off to Gunns Plains next weekend.
Colin and I took a short ride out to Bishopsbourne on Tuesday. The new gearing with the 45 tooth feels good. Yes, it isn’t as fast as the larger 52 tooth I have been using but triking isn’t all about speed – unless it’s a good downhill section. All went well until about 20 kilometres in and 5 ks from home the new hosepipe chain tube detached from it’s anchor point, shot into the chainring assembly and the chain plus pipe fell off the rings.
I have now used gaffer tape on the anchor point while I work out a better way to keep all in place.
I wonder if the chain running through the hosepipe is experiencing a bit more friction thus putting more strain on the anchor? Further testing will tell me the answer.
Rides of the Week
Gunns Plains Ride 1 – The Longer Ride
As you can see, this ride is short at 30 kilometres but features 570 meters of climbing. There is also a shorter ride available. I will be riding with a group on Sunday and decided to tackle the longer one on my own on Saturday as Bluey and I climb slowly but surely and I don’t want to hold everyone up.
On Friday I pulled the caravan along to Wings Caravan Park at Gunns Plains. Wings is actually a small zoo plus some powered and unpowered camping sites.
Began as a cloudy day but with patches of blue sky showing. Around 5-6°C it wasn’t too cold either.
I set off having put the chain onto the smaller front ring. This setting gives the best chainline so I was assured the chain wouldn’t be falling off. The initial part of the ride from Wings into Gunns Plains itself was alongside a creek that flows into the Leven River.
Through Gunns Plains and I noticed that the shop which was open last time we were here (6-7 years ago), has now closed. The only place open to buy anything is now at the zoo / caravan park. Luckily they have a large Cafe too!
Turn right and I started up Robert Road heading towards Preston. The climb began almost immediately. This is just what I wanted. Will the 38 tooth chainring work with the motor to allow me to spin comfortably during a decent climb?
Yes it did! On this ride I used low power and bottom gear to cruise slowly up at a general speed between 5 and 6 kph. The motor was pulling some power out of the battery but not much and I was getting exercise. Win .. Win.
The views were good until the forest closed in. Up and up the road went through some lovely stands of trees which looked like they might be Blue Gums. Then we began to find man ferns dotted amongst the trees.
What a nice ride – a great variety of things to look at.
Anyway the spinning and low use of power got me to the point where the road levels out with both trike and Tony feeling good but getting wet as it had started raining. The sort of rain which starts gently, hardly wetting you, but then gathers force. Just as I was really thinking about wet weather gear – it stopped. As we progressed along some lumpy undulating roads the rain came and went but never enough to demand full wet weather clothing. Undulating did I say? They were significant lumps in the road – 50kph down and 5 kph up then other side!
This carried on until I turned left onto Gunns Plains Road. After an initial climb we were then into my favourite territory – a long, windy descent with lots of it over 50 kph. With no traffic coming up behind and only a couple coming up I was able to give the trike it’s head, only braking for a couple of the tighter bends before hitting the flats down by the Leven River once more.
For the afternoon activity I visited the Gunns Plains Caves. There is a lot of limestone in the general area and (I was told) there are 154 known caves. The one I visited was found by the settlers many years ago by someone chasing a possum – or chasing their dog chasing a possum down into it.
A river flows through the cave and platypus live in it. We didn’t see any though. Apparently the cave can flood with water filling its entire height. This washes the platypus out and it’s a while before they find their way back.
It was an interesting cave but I could have done without the jokey guide who didn’t seem to like contemplative silence.
Day 2 – Gunns Plains Loop (n). n + 1
My plan had been to tackle the easy ride on Sunday but I had enjoyed yesterday’s ride so much I was in two minds – long ride or short ride. Guess what? I couldn’t resist another crack at the Gunns Plains Road descent so long ride it was.
During an initial look at all the bikes I was pleased to see a great variety. One guy had been developing his bike from parts found at the Tip – for the past 10 years! It was built from all sorts of mis-matching bits and goes well. Another bloke had this.
After getting our instructions for the day the group set off up Robert Road and I was soon left well behind. “Blow this for a game of soldiers” I thought – let’s up the power and see how quickly the battery empties itself. I know pulling power out at higher levels uses more power but then you get there faster. It’s like that old chestnut – do you get wetter if you walk or run a set distance through the rain.
I had used a newly charged battery yesterday and was using the second newly charge battery today. I will be able to check the levels of both afterwards. An interesting test.
So I upped the power levels and began using levels 4,5 and 6. I caught up with the group as they stopped and took a short walk to go look at Preston Falls. After viewing the falls I then used higher power levels to stay with them – now riding at 12kph up the hills rather than yesterday’s 5-6. The 38 tooth gearing was again feeling really good for the climb. By balancing input between levels 4 and 5 I was able to tag along nicely.
After turning left and hitting the undulations the group and I were doing a bit of overtaking. Me taking them going downhill and then being overtaken up hill. Luckily this doesn’t seem to piss them off. Some groups don’t like it. I am starting to like this group!😄
We stopped and re-grouped at the start of the descent and I took off first as everyone started to move. One rider gallantly tried to stay with me but I shrugged him off on the first set of bends! We raced down Gunns Plains Road until it levelled out where he caught me and then a few others trickled in behind. They had been trying to catch me and were impressed with the downhill ability of the trike.
Then it was back to the Cafe for lunch and much tale telling. I was able to find out some more about the proposed shared trail between Wynyard and Latrobe as a couple of the riders are on the Committee working for the rail trail. At the Wynyard end it will use the disused railway and a loud group is totally anti the proposal. They are demanding a light rail service be installed instead. This is also happening along the proposed Scottsdale – Launceston rail trail. While the benefits of rail trail shared paths is understood in Victoria, South Australia and NSW, Tassie just doesn’t get it. Too many have their heads in the clouds thinking a light rail service would be viable and will brook no compromise. There is room for both.
So, how do I now feel about the dual chainring? Well, the 38 tooth ring gives me what I have been seeking for uphill work. The 45 tooth is too low for general cruising with a group. It’s OK for solo rides and riding with Colin but to try and ride with a faster group it’s not really suitable.
I need to spend some time on the ‘Net with Sheldon Brown’s Gear Calculator .. will a Rohloff be the answer!!?
Both batteries are 36v / 16ah and have a voltage of 41.(and a bit) when fully charged. They discharge until the voltage reads 32 when the Controller cuts them off to prevent cell damage. I checked the batteries the day after the 2 Gunns Plains rides. The battery used on Saturday (lower power levels) reads 36.8 and the one from Sunday reads 36.5! Nothing much in it. A surprise.
It held up well !
I am working with iMovie which came with the new laptop. I am getting there but still a lot to learn. You will notice some screeching noises as Bluey and I climb Robert Road. I can’t hear them when riding but the camera microphone picks it up. Don’t know how to quieten them as yet – and I haven’t explored the motor to see if something is wearing out!
Till next time …….