Conversion for daily 20 mile commute

[jake369]

Hi - I've been reading posts for a while now ever since I found out that conversion kits (Panda and Cyclocity) are quite cheap. I have a 20 mile commute along flat roads, sometimes against wind (one way, wind behind me on the way home!). I'm an experienced cycle tourer (and have a different touring bike for this) but I currently find that after a week of cycling I'm not really in the mood for weekend cycling, which is disappointing. With that in mind, I'm looking for pedal assistance to make the weekly cycling less effort.

I have a Marin Fairfax SC2, a hybrid bike - does it seem a good candidate for conversion?

I was originally thinking of front wheel drive (with PAS) with battery on the rear rack, but I wonder if that is rather heavy over the back wheel (along with pannier with laptop etc.. for work) and for 20 miles do I need all the battery power. I wonder would a bottle battery be better, lighter when no need for the extra battery power?

I also have a question about the brake cut off switch. My gear controls are part of the brake lever, what do people do when that is the case?

 

[Deleted member 4366]

Rear motor with battery on the downtube will be much better. better steering, better traction and better handling. How much do you want to spend?

You can make or buy a brake cable sensor, You only need one on the back brake. It costs about £3 or less if you make your own.

 

[jake369]

Great news about the brake cable sensor, I'll see what I can find on that.

The bike has a cassette rather than a freewheel on the rear which I think rules out rear motor from what I read?

Budget wise I'm not wanting to spend more than £500.

 

[awol]

Possibly the XF08-CST kit from Woosh at £499.
If you need a 700c wheel I think Woosh will change it for a reasonable fee.
http://wooshbikes.co.uk/?hubkits
Also the OxyDrive Kit at £525
http://www.oxydrive.co.uk/electric-bike-kit/oxydrive-cst-ht-13ah.html
Both kits take cassettes

 

[anotherkiwi]

Great news about the brake cable sensor, I'll see what I can find on that.

The bike has a cassette rather than a freewheel on the rear which I think rules out rear motor from what I read?

Budget wise I'm not wanting to spend more than £500.

No you change the whole rear wheel freewheel or cassette makes no difference other than... How many gears? There are rear hub motors with cassettes but the limit is an 8 speed cassette without having to stretch the frame too much. Freewheel hubs are pretty much limited to 7 speed.

You need less gears when you have a motor so an 8 speed is fine.

 

[jake369]

9 speed cassette on the back. I've checked the front forks for clearance, I shall check out the rear as I'm unsure for that as I didn't think of rear motor at all

 

[Deleted member 4366]

Both of those kits, Woosh and Oxydrive, have cassette motors, so you just take the cassette off your wheel and stick it on the motor wheel.

The ready-made brake cable sensors are called hidden wire brake sensors. You can find them on Aliexpress. you have to cut the wire off the unwanted brake lever to join it to the system. Alternatively, you can buy the cheapest cycle computer from Ebay or look in your garage for that one you had that packed up. Cut the head off, fix the magnet to the brake cable where it runs along the crossbar and fix the sensor to the crossbar so that the magnet moves over to the sensor when you apply the brake. It's just a reed switch. Like the HWBS, you join the two wires to a connector cut off one of the brakes

 

[Nealh]

I've 2 9 sp cassette hubs and no need to stretch drop outs as they both fit 135mm d/o.

 

[jake369]

Hi - just a bit of an update, thanks for all your advice. I think I am almost there to put in an order for http://www.oxydrive.co.uk/electric-bike-kit/oxydrive-cst-ht-13ah.html before the special offer runs out. I will need to do something for the cutoff as I don't want to replace my brake levers/gear shifter.

Doing a rough measurement, it looks like my drop outs are 130mm and not 135mm, with an aluminium frame does that give me any options? (where did I get 135 from I wonder, something I read somewhere maybe?)

 

[Nealh]

The kit comes with a pair of wired brake levers you only need one sensor to be honest and probably on the left rear brake lever. As the levers supplied are cheap fairly basic ones remove the sensor with lead and fix/epoxy glue the sensor to your lever and fit the magnet where it will actuate the cut off.

 

[anotherkiwi]

I rode my hub drive bike for 3200 km without ever needing a brake cutoff (no throttle mounted). If you aren't mounting a throttle you probably don't need a brake cutoff on a hub motor bike. I have one on my GSM bike because I was having issues with motor run on and also PAS being very sensitive.

 

[Deleted member 4366]

130mm 135mm frame makes no difference. It's elastic.

 

[jake369]

That's what I thought (hopped!)

I think I'm ready to go and put an order in tomorrow!

 

[Paul Young]

I've done about 2500 miles without any brake sensors and have never seen the need eirher, with pedal assist stop pedaling then brake, or if you use a throttle, let go then brake, I'm sure most peoples brains work that way anyway.....

 

[danielrlee]

I rode my hub drive bike for 3200 km without ever needing a brake cutoff (no throttle mounted). If you aren't mounting a throttle you probably don't need a brake cutoff on a hub motor bike. I have one on my GSM bike because I was having issues with motor run on and also PAS being very sensitive.

Its funny really. I did thousands of miles on throttle only without any brake cutouts and it was only when I added PAS that I felt I needed them.

 

[anotherkiwi]

Its funny really. I did thousands of miles on throttle only without any brake cutouts and it was only when I added PAS that I felt I needed them.

PAS can't jam WOT if something breaks. I bet it was the issue of PAS being very sensitive and kicking in at the slightest forward pedal movement like with my GSM was it?

 

[danielrlee]

PAS can't jam WOT if something breaks. I bet it was the issue of PAS being very sensitive and kicking in at the slightest forward pedal movement like with my GSM was it?

I always like to protect from *on* failure modes with a kill switch that cuts power to the controller MCU through the ignition wire, so was always covered in the event of a 'stuck throttle', even though it never happened.

It wasn't so much the sensitivity of PAS, more the unpredictability of it that led me to brake cutouts. Even with a 12 magnet PAS disk, I never feel totally at ease with the system, but I imagine that a torque sensor would negate this issue.

 

[Woosh]

I think torque sensor may be worse in this case. The output of the torque sensor is not zero Volt on power up and may spike without movement, just playing with the pedals.
On my Sport TS, we use the rotation sensor to confirm that the bike is moving. So you lose that valuable feeling that the bike obeys your command immediately. It has not compared well to a throttle.

 

[danielrlee]

I think torque sensor may be worse in this case. The output of the torque sensor is not zero Volt on power up and may spike without movement, just playing with the pedals.
On my Sport TS, we use the rotation sensor to confirm that the bike is moving. So you lose that valuable feeling that the bike obeys your command immediately. It has not compared well to a throttle.

Hmmm, interesting. I wouldn't mind 'predictably sensitive'. Combined with maybe a Cycle Analyst, I'd like to try using a torque sensor without any torque multiplication - basically a pressure sensitive speed sensor. Something I might have to try in the future perhaps.

 

[jake369]

Well, the kit arrived the day after I ordered it!

I knew I didn't yet have the tools to swap over the cassette, but I thought I would start fitting everything else this evening. I did have a go at fitting the wheel and it went in without too much trouble, I will probably need some spacers to widen the forks a bit as I think with the cassette the chain might rub the frame.

I plugged everything in with the bike upside down and great excitement when the wheel started turning on upon giving it a bit of power with the throttle.

Amazingly, although not too surprising, the hardest bit so far has been fitting bits onto the handlebars. The handlebars are wide in the middle with a slight taper down to normal size nearer the grips. This has caused me no end of hassle over the years trying to fit lights and other such things which don't like how wide they are or the shallow taper. It was similar this evening trying to fit the display, in the end I was able to just about get it all on by pulling out the grips a bit to give me a bit more handlebar to work with. A bit of swearing was involved.

Annoyingly, the PAS sensor does not fit as there is so little room on the bottom bracket axle - one of the reason I liked this kit was because the sensor comes in two parts, no need to remove the crank etc.. I am thinking I need to replace the bottom bracket with something a bit longer. I will see how I get on without PAS to start with.

The cassette tools should arrive from Amazon later next week, but I might just go to my local bike shop tomorrow and buy a new 9 speed cassette and tool, I hate waiting! Also, upon doing a chain wear test I found out it is over worn (one year usage, around 4000 miles) - so new chain and cassette is probably what I would do anyway.