Filing dropouts?
08-06-17 | 11:22 AM
#1
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Bikes: Now: HPV Gecko FX 20 w/ assist.. Old: Trident Spike 2 recumbent trike w/ e-assist
Filing dropouts?
So I bought an e-bike kit and it seems like some owners have had to file their dropouts to fit the axle. I have a steel fork, and concerned that filing the paint away could leave it open to rust. Is that an issue? Is it normally possible (and safe) to file down the axle instead of the dropouts? I will be fitting the e-bike wheel only 20% of my riding time and using my regular wheel the rest of the time - if I file the dropouts to fit the e-bike wheel is that going to be an issue with a loose regular wheel?
thanks, guys...
thanks, guys...
08-06-17 | 12:06 PM
#2
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From: socal
Bikes: DIY
I had to file the steel front dropouts on my first conversion; didn't consider the axle since it's already hollow and to me barely strong enough. IMO, AND I COULD BE WRONG, the wheel rests on the dropout and is held by pressure from the inside dropout against the wheel. Accordingly, I DON'T THINK THE STRENGTH WOULD BE IMPAIRED. The other side of the coin is that a problem could be catastrophic. Probably I'll never change mine back so it's moot.
08-06-17 | 04:00 PM
#3
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Joined: Dec 2011
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From: 98059
Bikes: Treks and a Moulton
> ... some owners have had to file their dropouts to fit the axle….. concerned that filing the paint away could leave it open to rust. Is that an issue?
It could be if you ride in rain a lot. Get some Boeshield, or just apply a very ‘light' smear of petroleum grease on the bare metal.
> Is it normally possible (and safe) to file down the axle instead of the dropouts?
Hub axles are hardened steel so it’s very difficult to create more than a shiny spot with a file. A stone bit with a Dremel will work, but I would NOT recommend altering the axle.
> …. if I file the dropouts to fit the e-bike wheel is that going to be an issue with a loose regular wheel?
No, not unless you overdo the filing. From what I’ve read [and experienced], dropouts that require filing are only a couple thousandths undersize [if that], and the interference can be from forging/casting flash or just the powder-coat paint. Use a new/sharp single-cut flat file and file both surfaces of the dropout on each fork leg equally. Keep the file flat against the surface, you don’t want to angle the slot’s sides. It isn’t difficult, just work slowly and check the fit frequently. Avoid altering the dropout’s curve at the top of the notch because that registers the axle’s position when the axle is fully seated, and messing up that will affect how the wheel rides in the fork. If not true, there might be some adjustment needed to the brake shoes. When you establish a fit, before doing the final tightening of the axle nuts, put bike on the ground [if you have been using a work stand] so that the weight of the bike fully seats the fork down onto the hub's axle. To directly answer your question, even if the end result seems a bit loose for the original wheel the axle nuts should hold everything securely in place. Bike parts are machined to standard sizing, so if there are tolerance differences, it won't be much. If your front hub is over 350w, also use a torque arm.
Your hub might vary a little, but this installation info from Clean Republic is typical. https://www.electric-bike-kit.com/ima...nstall7.10.pdf
It could be if you ride in rain a lot. Get some Boeshield, or just apply a very ‘light' smear of petroleum grease on the bare metal.
> Is it normally possible (and safe) to file down the axle instead of the dropouts?
Hub axles are hardened steel so it’s very difficult to create more than a shiny spot with a file. A stone bit with a Dremel will work, but I would NOT recommend altering the axle.
> …. if I file the dropouts to fit the e-bike wheel is that going to be an issue with a loose regular wheel?
No, not unless you overdo the filing. From what I’ve read [and experienced], dropouts that require filing are only a couple thousandths undersize [if that], and the interference can be from forging/casting flash or just the powder-coat paint. Use a new/sharp single-cut flat file and file both surfaces of the dropout on each fork leg equally. Keep the file flat against the surface, you don’t want to angle the slot’s sides. It isn’t difficult, just work slowly and check the fit frequently. Avoid altering the dropout’s curve at the top of the notch because that registers the axle’s position when the axle is fully seated, and messing up that will affect how the wheel rides in the fork. If not true, there might be some adjustment needed to the brake shoes. When you establish a fit, before doing the final tightening of the axle nuts, put bike on the ground [if you have been using a work stand] so that the weight of the bike fully seats the fork down onto the hub's axle. To directly answer your question, even if the end result seems a bit loose for the original wheel the axle nuts should hold everything securely in place. Bike parts are machined to standard sizing, so if there are tolerance differences, it won't be much. If your front hub is over 350w, also use a torque arm.
Your hub might vary a little, but this installation info from Clean Republic is typical. https://www.electric-bike-kit.com/ima...nstall7.10.pdf
08-06-17 | 05:49 PM
#4
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Bikes: Now: HPV Gecko FX 20 w/ assist.. Old: Trident Spike 2 recumbent trike w/ e-assist
> ... some owners have had to file their dropouts to fit the axle….. concerned that filing the paint away could leave it open to rust. Is that an issue?
It could be if you ride in rain a lot. Get some Boeshield, or just apply a very ‘light' smear of petroleum grease on the bare metal.
> Is it normally possible (and safe) to file down the axle instead of the dropouts?
Hub axles are hardened steel so it’s very difficult to create more than a shiny spot with a file. A stone bit with a Dremel will work, but I would NOT recommend altering the axle.
> …. if I file the dropouts to fit the e-bike wheel is that going to be an issue with a loose regular wheel?
No, not unless you overdo the filing. From what I’ve read [and experienced], dropouts that require filing are only a couple thousandths undersize [if that], and the interference can be from forging/casting flash or just the powder-coat paint. Use a new/sharp single-cut flat file and file both surfaces of the dropout on each fork leg equally. Keep the file flat against the surface, you don’t want to angle the slot’s sides. It isn’t difficult, just work slowly and check the fit frequently. Avoid altering the dropout’s curve at the top of the notch because that registers the axle’s position when the axle is fully seated, and messing up that will affect how the wheel rides in the fork. If not true, there might be some adjustment needed to the brake shoes. When you establish a fit, before doing the final tightening of the axle nuts, put bike on the ground [if you have been using a work stand] so that the weight of the bike fully seats the fork down onto the hub's axle. To directly answer your question, even if the end result seems a bit loose for the original wheel the axle nuts should hold everything securely in place. Bike parts are machined to standard sizing, so if there are tolerance differences, it won't be much. If your front hub is over 350w, also use a torque arm.
Your hub might vary a little, but this installation info from Clean Republic is typical. https://www.electric-bike-kit.com/ima...nstall7.10.pdf
It could be if you ride in rain a lot. Get some Boeshield, or just apply a very ‘light' smear of petroleum grease on the bare metal.
> Is it normally possible (and safe) to file down the axle instead of the dropouts?
Hub axles are hardened steel so it’s very difficult to create more than a shiny spot with a file. A stone bit with a Dremel will work, but I would NOT recommend altering the axle.
> …. if I file the dropouts to fit the e-bike wheel is that going to be an issue with a loose regular wheel?
No, not unless you overdo the filing. From what I’ve read [and experienced], dropouts that require filing are only a couple thousandths undersize [if that], and the interference can be from forging/casting flash or just the powder-coat paint. Use a new/sharp single-cut flat file and file both surfaces of the dropout on each fork leg equally. Keep the file flat against the surface, you don’t want to angle the slot’s sides. It isn’t difficult, just work slowly and check the fit frequently. Avoid altering the dropout’s curve at the top of the notch because that registers the axle’s position when the axle is fully seated, and messing up that will affect how the wheel rides in the fork. If not true, there might be some adjustment needed to the brake shoes. When you establish a fit, before doing the final tightening of the axle nuts, put bike on the ground [if you have been using a work stand] so that the weight of the bike fully seats the fork down onto the hub's axle. To directly answer your question, even if the end result seems a bit loose for the original wheel the axle nuts should hold everything securely in place. Bike parts are machined to standard sizing, so if there are tolerance differences, it won't be much. If your front hub is over 350w, also use a torque arm.
Your hub might vary a little, but this installation info from Clean Republic is typical. https://www.electric-bike-kit.com/ima...nstall7.10.pdf
08-08-17 | 07:21 AM
#5
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Joined: Jul 2010
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From: Michigan
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Well, I would file the threads off the axel if that is an issue, and then try to do minor filing on the axle. It depends on how the axle is made.
When filing steel (dropout), I put a light coating of rustoleum on it to protect it and keep it from rusting. The tricky part with the axle is that it was never designed to take much torque, and its easy to spin the axle in the fork and bend or break the fork causing a very harsh crash. It does need to fit tight, and in a way where it will not spin under full torque of the motor. Torque arms are a good idea. (axle nuts will hold the wheel, but they don't do much from preventing the torque of the motor from rotating and breaking the fork ends).
When filing steel (dropout), I put a light coating of rustoleum on it to protect it and keep it from rusting. The tricky part with the axle is that it was never designed to take much torque, and its easy to spin the axle in the fork and bend or break the fork causing a very harsh crash. It does need to fit tight, and in a way where it will not spin under full torque of the motor. Torque arms are a good idea. (axle nuts will hold the wheel, but they don't do much from preventing the torque of the motor from rotating and breaking the fork ends).
08-10-17 | 10:06 AM
#6
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Joined: Sep 2015
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I would not file the axle ever.
The minimal amount you will have to take off the frame should not even start to weaken it.
Rust? I'm assuming you are a fair weather rider---I am--paint is really cheap if you are worried about it.
I would not be converting from E-bike and back. It is a total pain. Get another bike.
The minimal amount you will have to take off the frame should not even start to weaken it.
Rust? I'm assuming you are a fair weather rider---I am--paint is really cheap if you are worried about it.
I would not be converting from E-bike and back. It is a total pain. Get another bike.
08-10-17 | 11:13 AM
#7
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From: SoCal
Bikes: As my watts decline, I’m amping up!
IMHO torque arms are mandatory and might also help hold the axle in place should the axle nuts loosen. Like others have said; don't file the alxe, file the fork and repaint. Easy!
08-11-17 | 08:59 PM
#8
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From: SF Bay Area
Bikes: Now: HPV Gecko FX 20 w/ assist.. Old: Trident Spike 2 recumbent trike w/ e-assist
Well, I decided the whole thing was just too much trouble. Although I know they are not terribly popular, I am actually going to wait for the new share roller friction drive. Less than 6 pounds with batteries, and easy on and off without removing the wheel. And I can use it on any bike so it would work on a 16" as well. Downsides: noisy, but I don't care about being all stealth since it something I would flick on just for hills or bad headwinds. Upside: light, easy to remove and zero drag unless I turn it on. Having to swap the hub wheel out would be a pain, I would be pedaling without power on a heavier bike, and it would only fit the one size bike. Don't want another bike. Not enough space. Thanks for all the replies - helped me decide for sure.
