My life with a Mac8T

[ronniec95]

Hi

I've not been on this site for a while but thought it might be interesting to give a long term review for those who are looking for a idea of what it is to own one. I know the top posts here are for people building insanely cool, high spec bikes, but for me who's not a mechanic/machining expect, just needs to get to work and back in a reliable way, thought it might be useful.

Bike:
I bought a Mac8T back in November 2013, along with a triangle battery 58v,18.5AH, and cycle analyst 3.
Installed in onto a on-one steel frame, with suspension forks and seat post.

Activities
I've been riding it as a commuter almost daily to work and back which is around 40Km round trip; and that's through both sunshine and rain (no snow as yet).
I've also used it to carry shopping home on occasion, but to be honest, weekends are with the wife/car (sorry ebikers)
It's become my go-to bike in almost all cases, though my regular road bike (Condor Fratello with Sram Red groupset) is definitely more fun, in a different way

Stats
Average distance daily: 32km
Average WH per day: 250WH
Average speed: 25km/h
Max speed on flat: 49km/h
Typical wh/km : 6-8wh/km
Total distance: 7500km
Cycling effort: Medium

Good points
Can outrun town traffic comfortably when needed
After a long day at work, makes journey home palatable, where on a regular bike I'd be less happy
Reliability on a day to day basis is good
It's amazingly fun when you open the throttle and just feel that kick; only felt the same on a tesla
The charger is good, but I'm looking to upgrade to the Cycle Satiator soon.

Bad points
Reliability of kit: I've had to replace the clutch after 2500km (gears fine, but started slipping) but got the upgraded Mac ones in return
The spoke have broken at least 3 times, so I got the whole thing re-laced in London with new rims and triple cross. This has improved strength and hasn't broken since
The wheels untrue fairly quickly compared to my regular bike, but with the new lacing is better
The rim-tape was substandard on the wheel


So all in all a good experience. I'd highlight for a end-user, the reliability of the Chinese parts and finishing is problematic; so that is what they could work on. So for anyone thinking of buying, my recommendation would be buy the motor and a spare clutch/gears, but get the wheel assembled at your LBS (if you can do it yourself, great)

 

[ronniec95]

Just to add. em3ev is where I got the parts; with Hyena supplying the original kit/instructions.

I've been very happy with Paul (em3ev) service.

 

[fesanand]

Really good wh/km!

But dont be shy and post a picture of the bike :wink:

When you say your average speed is 25kmh:
is that average speed of cyclo computer?
Or is the speed you tend to cruise most of the time?

My average speed in the cyclo computer is 25 as well but i normally cruise at 35kmh.

Cheers

 

[bowlofsalad]

Bad points
Reliability of kit: I've had to replace the clutch after 2500km (gears fine, but started slipping) but got the upgraded Mac ones in return
The spoke have broken at least 3 times, so I got the whole thing re-laced in London with new rims and triple cross. This has improved strength and hasn't broken since
The wheels untrue fairly quickly compared to my regular bike, but with the new lacing is better

3 cross is(probably) excessive spoke angle. Excessive spoke angle can cause spokes to break just beneath the threads. There is no advantage to 3 cross over 1 cross so far as I know. http://www.ebikes.ca/tools/spoke-calc.html Use this tool to see spoke angle, with a 622 rim I came up with around 74 degrees Even with sapim polyax nipples the maximum is supposed to be around 9(81) degrees for spoke angle. If you bought the wheel prelaced, and didn't get their custom wheel build with sapim spokes, it probably isn't much of a surprise that those stock spokes broke. What spokes and rim are you using? If you ever rebuild, I'd go with 1 cross.

Thinner spokes are going to be better over thicker ones, assuming you are using a bicycle rim. Spokes stretch as you place them under tension, this stretching sounds unlikely but it's a key element to a spoked wheel. This stretch helps prevent the spokes from losing tension when the spokes and rim compress and wobble as you go over a bump. You cannot attain the amount of stretch necessary for this idea with thicker spokes using a bicycle rim, straight 12 and 13 gauge spokes require substantially more tension for the ideal amount of stretch. So 13/14ga spokes, 14/15/14, or 13/15/14 spokes are probably ideal, depending on various ideas. A good go to is likely to be the 13/14ga sizing. So when you use thinner spokes that stretch well when using bicycle rim tension levels, this prevents the spokes from losing tension, this protects the spokes(loose spoke is worthless) and helps keep the rim true.

There are two more things that will help largely will wheel reliability, lower motor weight and suspension. The Q100h weighs 2.2Kg, if you can keep it cool (sounds like you might be able to) you can use that hub instead. As for suspension, the first place to look to are the tires, wider is better. From there I think the rest of the suspension discussion is obvious, full suspension will help soften those hard knocks, protecting your wheels among other things.

I am a bit surprised the clutch broke so quickly. Personally I am not a fan of clutches on hub motors. Personally I'd rather lock the clutch and have reverse and regenerative braking.

 

[spinningmagnets]

Thanks for the long-term report. Would you happen to know how many max amps you are hitting on acceleration?

 

[ronniec95]

Hi guys

Some pics attached

The bag at the back just contains work clothes and is not ebike related. Battery, controller, wiring all fitted in the frame bag. Front chain ring is 40T which allows me 90-100rpm at 45kmh. I ride a regular bike too so I'm happy with high cadence riding.

fesanand : Cyclcocomputer saying ~25kmh, but yes I tend to cruise around 35-40kmh which is just right for traffic streets.

spinningmagnets : I've seen around 18amps reported on the CA after a trip. But usually I tend to kick off with pedaling and then open up. Mainly because I counted the number of traffic lights (nerdy I know) between my home and work, and there's 121 so I can't really accelerate much.

bowlofsalad : I got the basic wheel build when I got it. OK I'm interested in 2 of your points. I'll take your email to the local shop (if that's ok) and see what they suggest on the 13/14ga spoke build; that's a lot easier to get hold of.
And more intriguingly, how do I 'lock the clutch'? Regen sounds great and would work with my style of riding. Any thread explaining how to do it?

 

[bowlofsalad]

bowlofsalad : I got the basic wheel build when I got it. OK I'm interested in 2 of your points. I'll take your email to the local shop (if that's ok) and see what they suggest on the 13/14ga spoke build; that's a lot easier to get hold of.
And more intriguingly, how do I 'lock the clutch'? Regen sounds great and would work with my style of riding. Any thread explaining how to do it?

Go for it.

I have never heard of anyone locking a clutch with a MAC before, I've heard of clutch problems and the motor ceasing freewheeling much like yours did. But, I imagine there must be a way to disable the clutch. I imagine your best bet is to buy http://em3ev.com/store/index.php?route=product/product&path=44&product_id=110 a few clutches, take them apart as best you can and grasp how they work.

Another potential route is you could possibly make a similar part that simply lacks the clutch functionality. It'd be just a disc of the same dimensions that holds three gears and an axle keyway, not a very complicated part.

 

[KarlJ]

NICE!
me too 8T, ~15AH 50V 20R pack for starters, will borrow a couple of mates' packs for the pipe challenge hoping for 44AH @50V on the bike for a couple of kwh!
Gen-set for charging them will be going hard!

Any problems with disc rub and or shifting being less than perfect when motor pushed hard (as if it grows shifts things a mm here or there i think).

My prev mac a 350W on a road bike on the front is excellent - considering running it for the pipeline challenge as lighter and simply cannot afford 2000W power anyway.