What am I missing?

[BruceBanner1983]

It's not really the direction of the axle slots that i the issue, but the thickness of the metal on many bikes in that location tends to be thin or of a lower quality material that lacks strength. From what I can see of yours they will be fine for most engines sold on the market.

I just measured my dropout thickness with digital calipers and they’re 0.195” thick. I plan on running a 212 with cvt. This is a good old schwinn cantilever frame.

 

[DieselTech]

I'm not trying to start no arguement. But isn't the issue: from the force of the chain yanking forward & down on the dropouts. Risk of yanking the wheel out of the dropout under hard acceleration. Also a risk of possibly bending the drive side dropout ear/wing down from force.

 

[BruceBanner1983]

I'm not trying to start no arguement. But isn't the issue: from the force of the chain yanking forward & down on the dropouts. Risk of yanking the wheel out of the dropout under hard acceleration. Also a risk of possibly bending the drive side dropout ear/wing down from force.

I wouldn’t think so. The ground is absorbing the down force from the wheel.

 

[ImpulseRocket]

I wouldn’t think so. The ground is absorbing the down force from the wheel.

Don't forget your Newtonian physics. Equal and opposite. The drive force is equally trying to lift the frame off the axle.

I have never had a problem with this and my current bike has the same style of dropout.

 

[BruceBanner1983]

Don't forget your Newtonian physics. Equal and opposite. The drive force is equally trying to lift the frame off the axle.

I have never had a problem with this and my current bike has the same style of dropout.

My dropouts being more than 1/8” thick I definitely don’t see this being an issue. They’re almost 0.2” thick.

 

[Sidewinder Jerry]

My dropouts being more than 1/8” thick I definitely don’t see this being an issue. They’re almost 0.2” thick.

On your frame it only looks like about a 1/2" of the stays connect to the dropouts. I suggest filling in the area from the boss on the chain stay to the dropout and seat stay. Increasing the dropouts by another 1/8" would also really strengthen them also.

 

[michael whiteman]

These are all possible issues to brainstorm, but personally I do not see any need for improvement. If you don't have your axle nuts tight, you're asking for trouble no matter what. And, if you really feel the wheel will "jerk" forward simply make a strap with a hole for the axle and bend a ninety in it to hook around the rear of the dropout plate. You might cut/grind a flat on the back side of the plate for this.

Regarding the forces acting on the dropout plate. The chain trys to pull the wheel out of the dropout........nothing structural. The weight of the bike is acting in a vertical plane through the axle. The major stress point will be the finger on the dropout that extends up inside the horizontal tube. It is trying to push itself up through the top of the tube. If there was going to be a stress fracture it would start on the upper weld joining the dropout to the horizontal bar, but the finger inside the tube will prevent this. ( the unknown is "how long is the finger") The horizontal bar absorbs the majority of the force seeing as the upper tube goes up at more than forty five degrees. There are mathamatical equations for all of this that none of us will go into, so the bottom line is this. Weld a gusset in the location shown above and sleep tight knowing you have made it all stronger.

This P-3 Ferrari is just one of many tubeular frame cars we built before I retired, so I have a little experience with this.

 

[BruceBanner1983]

These are all possible issues to brainstorm, but personally I do not see any need for improvement. If you don't have your axle nuts tight, you're asking for trouble no matter what. And, if you really feel the wheel will "jerk" forward simply make a strap with a hole for the axle and bend a ninety in it to hook around the rear of the dropout plate. You might cut/grind a flat on the back side of the plate for this.

Regarding the forces acting on the dropout plate. The chain trys to pull the wheel out of the dropout........nothing structural. The weight of the bike is acting in a vertical plane through the axle. The major stress point will be the finger on the dropout that extends up inside the horizontal tube. It is trying to push itself up through the top of the tube. If there was going to be a stress fracture it would start on the upper weld joining the dropout to the horizontal bar, but the finger inside the tube will prevent this. ( the unknown is "how long is the finger") The horizontal bar absorbs the majority of the force seeing as the upper tube goes up at more than forty five degrees. There are mathamatical equations for all of this that none of us will go into, so the bottom line is this. Weld a gusset in the location shown above and sleep tight knowing you have made it all stronger.

This P-3 Ferrari is just one of many tubeular frame cars we built before I retired, so I have a little experience with this.

All yall basically saying my dropouts are thick enough to withstand the force, so I ain’t too worried about it.

 

[robe]

Interesting stuff Guys. I've been considering how to improve the drop outs on my new bike. I do like the idea of horizontal slots for chain tension adjustment but greater minds than mine say it is not necessary. I'm a long way out before I start on it so I have plenty of time to decide what to do. Thanks.

 

[GW's Motorized]

Interesting stuff Guys. I've been considering how to improve the drop outs on my new bike. I do like the idea of horizontal slots for chain tension adjustment but greater minds than mine say it is not necessary. I'm a long way out before I start on it so I have plenty of time to decide what to do. Thanks.

They aren't necessary, but they are nice to have to tension the chain.