GoldenMotor.com Forum
General Category => General Discussions => Topic started by: diverdon on February 28, 2024, 09:48:14 AM
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Hello , First I have got to say I'm so VERY Happy with my Magic Pie setup .. I ride 1 1/2 or 2 1/2 hours most every day and it has helped with my health a lot ...
Today I noticed a "knocking" noise when I went over bumps ... I ride slow 7-8 mph average .. Got home looked it over and it seems the steering head bearings came/got a little loose ..Tightened the nut 1/8th of an inch and the looseness is out now ...
Thing is ...Question is .. I posted in another forum looking for an exploded diagram of the steering head .... And someone came back with a comment that "I Better Change to a rear hub motor or the bike is going to "Grenade" ...
I didn't really appreciate that "help" ... Been riding this bike for over 3 years with no problems ...seems to me replacing the steering head bearings would just be a maintainece item ... I have done the rear hub 2 times already ..
Looking at the Bike in a picture I CAN see where a motor tugging on that front wheen could/might cause a problem ...
Can I get some opinions ? Please ? Seems there are thousands of front hub motors and I have never heard of steering head failures from them ...
Thank You for any help you can give ... Don
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Hi Don,
As you have steel forks that are also fitted with a torque arm you don't need to worry, as the load on the headset is significantly greater from heavy braking forces applied to a conventional wheel than the torsional forces generated from a front mounted hubmotor under full power. ;)
Forks that are able to be used with disc brakes would be the best option for a front mounted hubmotor as they are designed to withstand torsional forces at the lower end, whereas non-disc brake forks only had to withstand directional forces from the wheel's axle:
(https://www.researchgate.net/profile/Syamil-Zakaria/publication/278669178/figure/fig7/AS:668369086840864@1536363016948/Force-acting-on-the-front-fork-Solving-for-the-moment-acting-F-B1-N-f-F-y-sin.ppm)
The biggest safety concern with a front mounted hubmotor is that the fork's dropouts are simply not designed to cope with any torsional loads from the axle in either direction when a conventional front wheel is used as the wheel bearings prevent this from happening.
However, with a hubmotor, the high torsional forces produced by the stator have to be transmitted through the axle, which is why torque arms should always be fitted when using a hubmotor to help withstand the bidirectional torsional forces produced by the axle within the dropouts while under power and during regenerative braking.
Alan
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Thanks again Alan .. I sorta thought that way ...but didn't have the science to back it up ..Now I do ..
I have torque arms on both sides .. good ones from Grin Technologies ..Canada .. And I ride pretty easy ..no big bumps and pretty slow 7-8 mph Average ..
Ordered a "headset" from Electra (treck) today .. Guess 3 years or so is about time to replace them anyhow ... I just don't like the bicycle being "broke down" .. Especally when the weather is so nice here now .. I tightened the bearings 1/8 inch ? gonna take a "test ride" now ....
Thanks Again Alan ..Your a lifesaver