Hi folks, I'm new to Pedlecs forum so apologies if this topic has been covered a trillion times already (couldn't find it, but then the forums here are very busy and very interesting!) I've just completed my first torque sensing, mid motor conversion on my girlfriends 25 year old Giant city bike, it all went well and was no more technically challenging then I expected. Thing is when lots of power is on the geers slip, I really cleaned and inspected the chain and cassette and both were visually in great condition. I suspect that this was naive of me and the only solution will be a new chain and cassette? Your thoughts?
Mid motor geers slipping
- Thread starter Rodders
- Start date
Incorrect adjustment of the B-screw on the back of the derailleur or the chain is too long. The motor puts four times as much force on the chain compared with you on your own. Problems might not show themselves until under maximum stress.
How many teeth on the original front chain wheel and how many on the motor [suspect the chain is to long]
As a rule of thumb i change the chain and rear cogs when upgrading to a mid drive for piece of mind
As a rule of thumb i change the chain and rear cogs when upgrading to a mid drive for piece of mind
Exactly my thoughts.
But do make sure (assuming derailleur gears) that the chain spring is correctly adjusted, so that the chain tension is correct.
I would replace cassette and chain as a minimum. The front chain ring will also be suspect for later....on a 25 year old bike.....
Remember, far more torque is transferred via the chain than previously....
The chain on the mid motors is considered to be the "Single point of failure" by many Bike journalists and others.
It will therefore need to be better maintained, and more often replaced, than a chain on a conventional bike, or one with hub motors, front or back.
With hub motors the stress on the chain is actually usually less than a conventional bike's chain, one driven over the same paths and roads..........
Stress = Wear!
For the future, replace 2 chains for one cassette aproximately....or 3 depending upon the wear rate.
Andy
Thank you, I will try shortening the chain and check the tension before changing the cassette and chain.
I doubt it is the freewheel slipping as it feels like it engages positively and this is very hard to prove anyway. I suspect the cassette will need replacing anyway.
Changing them will simply remove two areas of possibly problems.
As the bike is old, does anyone exactly know when they were last changed?
I admit to changing chains regularly on my first e-bike, but until the chain started dropping off on each and every ride, I did not change the cassette. But that brought instant peace!
I also changed it for a cassette with a slightly higher top gear, which improved comfort, as it reduced the RPM of the pedals at 25KM.
Reminder (there may be more), there are at least two types of cassette, they are not compatible. Also, some special tools are needed, which are all in a reasonably cheap box of bike tools, if you need to buy them. Sadly, I don't remember if the same tools work for both cassette types, as its a year or so back, sorry!
But someone here will know exactly and help you better than I!
Andy
Thanks Andy, having built lots of bikes over the years I have had limited success at changing cassettes myself so I always taken the wheel to the bike shop to get the cassette changed - so much less hassel. The front chainrings were quite worn but the chain and cassette looked perfect so I may have changed them quite recently but, sadly, my memory isn't what it was!
Can you clarify what you mean by 'slipping'
Does it do it in all gears or just the smallest cogs at the back?
Old cogs and chains, although looking fine are subject to chain skip, where the chain actually skids over the top of the teeth on the rear cog, particularly an 11 toothed cog.
Generally it is momentary, you feel a bang from the back as the chain skips and then reconnects.
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