MtbWalker
Member
not talking about the power output, what is the difference mechanically and design wise between the 1.1 and the 2.2 motors? And why do the 1.1 motors seem to be more reliable?
Kenevo Gen1 2.2 vs 1.1 mechanical difference?
- Thread starter MtbWalker
- Start date
As a quick overview :
There was the original 1.2 - this suffered from some over heating problems and led to the development of the 1.2e (Drive T - generally starting with a serial number of C911). The main difference between the 1.2 and the 1.2e (which is the main one used) was a reduction in power to avoid the heat issue.
In turn, the 1.3 (Drive S - generally starting with a serial number of C972) was developed which was a fairly significant re-work. The weight dropped from 3.9kg's to 3.4kg's. The power was upto 90nm - 20a max draw (after the 5.0.4 firmware updates). A crankshaft seal was also introduced on the right hand side which hadn't been there previously. On the whole it's a fairly reliable motor, but will still suffer from moisture ingress from jet washing or prolonged/unlucky immersion. Pedal strikes also run the risk of belt or sprag bearing damage - though full failure from the impact invariably doesn't happen at the time of impact.
Then the 2.1 came along - the Mag S. Significant use of magnesium and a complete re-work of the casing and mountings dropped the weight to 2.9kg's.
The Brose is the only motor using an internal belt. The 2.1 has seen various changes with "stronger" belts and "wider" belts - whilst belts do fail, it's more normal for the sprag bearings to fail rather than the belt, though the effect will be the same. The "2.2" is just the same 2.1 , but with a new number assigned for marketing purposes - it should include all the previous cumulative upgrades and modifications, but there was no set serial number change. Motors produced after approximately July/August 2020 should have all the latest upgrades.
A more in depth explanation on why some of the failures happen was written by @Bearing Man :
You have two sprag clutch bearings in the motor, one to disengage your crankshaft from your chainring when you stop pedaling and one to disconnect your motor from your chain ring. These sprag bearings were designed to be fitted into a machine to stop the machine from rotating backwards after coming to a rest.
The bearings are designed to take a maximum load of approx 240Nm, and it's not really designed to high shock loads like each time you stop pedalling to coast - when you start pedalling again the motor kicks in (without soft start) and races to catch-up with the crankshaft that you're spinning up with your feet and the sprag bearing has to arrest the motor as it meets your 60 or 70 rpm cadence. Over rough ground, this can be happening very regularly and eventually smashes the sprag bearing to pieces and you loose drive believing your belt has snapped.
The crankshaft sprag bearing goes through even more ! The chain is snatching at it as it goes slack and tight, pedalling, not pedalling, suspension going up and down altering the chain length etc.
This all transmits to the chainring and back to the sprag bearing .Then what happens when you hit a tree root or rock with your pedal? Lets say you have a 100Kg rider and a 25Kg bike traveling at 15mph and hitting a tree root with the crank ! This is the equivalent of hitting your crankarm with a 125Kg sledge hammer against a bearing designed to take 240Nm.
There is another particular reason for failure on the 2.1 and 2.2 motors and that is the large drive belt pulley support bearing moving !
On the earlier 1.2 and 1.3 aluminium motors, this bearing is crimped in and rarely moves. On the 2.1 and 2.2 motors, the crimps do not work because the housing that contains the bearing is magnesium alloy and too brittle to crimp. To get around this, the bearing is glued in place and a hard pedal strike or crash blow to the left crank will punch the bearing from the housing and once the two belt drive pulleys are running out of alignment, the belt will fail.
The crankshaft sprag bearing is locked while you are pedalling.
There was the original 1.2 - this suffered from some over heating problems and led to the development of the 1.2e (Drive T - generally starting with a serial number of C911). The main difference between the 1.2 and the 1.2e (which is the main one used) was a reduction in power to avoid the heat issue.
In turn, the 1.3 (Drive S - generally starting with a serial number of C972) was developed which was a fairly significant re-work. The weight dropped from 3.9kg's to 3.4kg's. The power was upto 90nm - 20a max draw (after the 5.0.4 firmware updates). A crankshaft seal was also introduced on the right hand side which hadn't been there previously. On the whole it's a fairly reliable motor, but will still suffer from moisture ingress from jet washing or prolonged/unlucky immersion. Pedal strikes also run the risk of belt or sprag bearing damage - though full failure from the impact invariably doesn't happen at the time of impact.
Then the 2.1 came along - the Mag S. Significant use of magnesium and a complete re-work of the casing and mountings dropped the weight to 2.9kg's.
The Brose is the only motor using an internal belt. The 2.1 has seen various changes with "stronger" belts and "wider" belts - whilst belts do fail, it's more normal for the sprag bearings to fail rather than the belt, though the effect will be the same. The "2.2" is just the same 2.1 , but with a new number assigned for marketing purposes - it should include all the previous cumulative upgrades and modifications, but there was no set serial number change. Motors produced after approximately July/August 2020 should have all the latest upgrades.
A more in depth explanation on why some of the failures happen was written by @Bearing Man :
You have two sprag clutch bearings in the motor, one to disengage your crankshaft from your chainring when you stop pedaling and one to disconnect your motor from your chain ring. These sprag bearings were designed to be fitted into a machine to stop the machine from rotating backwards after coming to a rest.
The bearings are designed to take a maximum load of approx 240Nm, and it's not really designed to high shock loads like each time you stop pedalling to coast - when you start pedalling again the motor kicks in (without soft start) and races to catch-up with the crankshaft that you're spinning up with your feet and the sprag bearing has to arrest the motor as it meets your 60 or 70 rpm cadence. Over rough ground, this can be happening very regularly and eventually smashes the sprag bearing to pieces and you loose drive believing your belt has snapped.
The crankshaft sprag bearing goes through even more ! The chain is snatching at it as it goes slack and tight, pedalling, not pedalling, suspension going up and down altering the chain length etc.
This all transmits to the chainring and back to the sprag bearing .Then what happens when you hit a tree root or rock with your pedal? Lets say you have a 100Kg rider and a 25Kg bike traveling at 15mph and hitting a tree root with the crank ! This is the equivalent of hitting your crankarm with a 125Kg sledge hammer against a bearing designed to take 240Nm.
There is another particular reason for failure on the 2.1 and 2.2 motors and that is the large drive belt pulley support bearing moving !
On the earlier 1.2 and 1.3 aluminium motors, this bearing is crimped in and rarely moves. On the 2.1 and 2.2 motors, the crimps do not work because the housing that contains the bearing is magnesium alloy and too brittle to crimp. To get around this, the bearing is glued in place and a hard pedal strike or crash blow to the left crank will punch the bearing from the housing and once the two belt drive pulleys are running out of alignment, the belt will fail.
The crankshaft sprag bearing is locked while you are pedalling.
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No worries.
Yes, the Mahle motor generally seems to be very reliable. It's not 100% without failures, but they're fairly rare.
