Weird half dropouts -- think it'll still work as a conversion?
10-26-21, 06:57 PM
#1
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Weird half dropouts -- think it'll still work as a conversion?
Maybe if I use a half link or something? I'm not sure how half links work. Seems like adding a full link should move the wheel a quarter inch, so a half link should move it an eighth of an inch? Seems like an eighth to a quarter inch is about all I have to work with here...
*Edit: I realize after thinking about it a second that you have to remove at least two links from a normal chain, which would move the wheel a half inch. So, for a regular chain you would need to get pretty lucky or need a half inch of space to move in the dropout. And for a half link chain (or do they make a half link insert you can attach to a regular chain?) you'd need a quarter inch of space to move.
*Edit: I realize after thinking about it a second that you have to remove at least two links from a normal chain, which would move the wheel a half inch. So, for a regular chain you would need to get pretty lucky or need a half inch of space to move in the dropout. And for a half link chain (or do they make a half link insert you can attach to a regular chain?) you'd need a quarter inch of space to move.
Last edited by cyrano138; 10-26-21 at 07:07 PM.
10-26-21, 07:08 PM
#2
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The issue you may encounter is that the slot may not be long enough to set proper chain tension without a
"magic gear." Some (ok, a lot) of elbow grease and a round file could extend the slot all the way back.
I've always considered those dropouts to be a stupid idea: marketing department going for a particular "look" rather than simply going with vertical dropouts.
"magic gear." Some (ok, a lot) of elbow grease and a round file could extend the slot all the way back.
I've always considered those dropouts to be a stupid idea: marketing department going for a particular "look" rather than simply going with vertical dropouts.
10-26-21, 07:13 PM
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No, a full link moves the axle a half inch and a half link moves the axle a quarter inch. You’ve got zero adjustability with those dropouts.
10-26-21, 07:34 PM
#4
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Or am I just high?
*Edit: I'm not not high, but I checked this with a piece of string and I'm right.
Can anyone think of a way to grind out the drops? I can try to find a round file that's about 10mm I guess. It would take so long.
Last edited by cyrano138; 10-26-21 at 07:40 PM.
10-26-21, 07:43 PM
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A full link is 1” long. Half of it goes on the top and half of it goes on the bottom, which is 1/2”. This is not a pulley, there is no mechanical advantage, the chain moves the same amount on the top as on the bottom.
10-26-21, 07:50 PM
#6
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I misread your response. I think we're both saying the same thing. If I use a regular chain I need a 1/2 inch of adjustability and if I use a half link I need 1/4 inch adjustability.
10-26-21, 07:59 PM
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10-26-21, 08:02 PM
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I had one of those on the drive side of the RockHopper, while the non-drive side has a full cut out and a little hardware piece that could go in and create a matching axle locator to the half dropout.
I don’t have a nice work stand, so I took mine to a local shop and had the owner take a hacksaw to the thing to extend the slot back along the shape of the dropout.
It ended up not making a lot of difference because the U-brake position limits me to basically what was already open and the stuff that was opened up is too far back for the U-brake to reach the rim and avoid the tire.
If you have a rear brake on the seat stays, you could probably extend the slot (very carefully and very precisely) and have a good range of usable locations, probably all four of the distinct locations.
Otto
I don’t have a nice work stand, so I took mine to a local shop and had the owner take a hacksaw to the thing to extend the slot back along the shape of the dropout.
It ended up not making a lot of difference because the U-brake position limits me to basically what was already open and the stuff that was opened up is too far back for the U-brake to reach the rim and avoid the tire.
If you have a rear brake on the seat stays, you could probably extend the slot (very carefully and very precisely) and have a good range of usable locations, probably all four of the distinct locations.
Otto
10-26-21, 08:07 PM
#9
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Thread Starter
Correct. You originally said that a full link change would move the axle 1/4” and a half link would move it 1/8”, which is incorrect. A half link is a male/female link which allows you add half link to a chain. https://www.retro-gression.com/colle...-1-8-half-link
10-26-21, 08:08 PM
#10
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Being flexible with a half-link and your chainring/cog choice will help. I would pick an arrangement that puts the axle toward the front of the dropout (but with full contact for the axle nuts) so that you have a bit of room to move the wheel back as the chain inevitably wears.
My Diamondback came to me with partially-filled dropouts like this, although I don't think they were this bad. The idea, as I understand it, was to force the rear axle into a particular spot in relation to the rear derailleur for more consistent indexed-shifting performance. (Some bikes had plastic stops installed in regular horizontal dropouts to accomplish the same thing.) It's why the industry went to vertical dropouts not long after.
In order to file the droputs to their full potential
, I propped up the frame on its rear so that the dropout slots were vertical, then used a round file and oil. That let me just file downward. I checked my work frequently with a spare 10mm axle to make sure I was opening it wide enough, but maintaining a straight line along the top of the dropouts. Hope this helps.
My Diamondback came to me with partially-filled dropouts like this, although I don't think they were this bad. The idea, as I understand it, was to force the rear axle into a particular spot in relation to the rear derailleur for more consistent indexed-shifting performance. (Some bikes had plastic stops installed in regular horizontal dropouts to accomplish the same thing.) It's why the industry went to vertical dropouts not long after.
In order to file the droputs to their full potential
, I propped up the frame on its rear so that the dropout slots were vertical, then used a round file and oil. That let me just file downward. I checked my work frequently with a spare 10mm axle to make sure I was opening it wide enough, but maintaining a straight line along the top of the dropouts. Hope this helps.
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Last edited by ThermionicScott; 10-26-21 at 08:11 PM.
10-26-21, 08:11 PM
#11
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Thread Starter
I had one of those on the drive side of the RockHopper, while the non-drive side has a full cut out and a little hardware piece that could go in and create a matching axle locator to the half dropout.
I don’t have a nice work stand, so I took mine to a local shop and had the owner take a hacksaw to the thing to extend the slot back along the shape of the dropout.
It ended up not making a lot of difference because the U-brake position limits me to basically what was already open and the stuff that was opened up is too far back for the U-brake to reach the rim and avoid the tire.
If you have a rear brake on the seat stays, you could probably extend the slot (very carefully and very precisely) and have a good range of usable locations, probably all four of the distinct locations.
Otto
I don’t have a nice work stand, so I took mine to a local shop and had the owner take a hacksaw to the thing to extend the slot back along the shape of the dropout.
It ended up not making a lot of difference because the U-brake position limits me to basically what was already open and the stuff that was opened up is too far back for the U-brake to reach the rim and avoid the tire.
If you have a rear brake on the seat stays, you could probably extend the slot (very carefully and very precisely) and have a good range of usable locations, probably all four of the distinct locations.
Otto
10-26-21, 08:13 PM
#12
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Thread Starter
Being flexible with a half-link and your chainring/cog choice will help. I would pick an arrangement that puts the axle toward the front of the dropout (but with full contact for the axle nuts) so that you have a bit of room to move the wheel back as the chain inevitably wears.
My Diamondback came to me with partially-filled dropouts like this, although I don't think they were this bad. The idea, as I understand it, was to force the rear axle into a particular spot in relation to the rear derailleur for more consistent indexed-shifting performance. (Some bikes had plastic stops installed in regular horizontal dropouts to accomplish the same thing.) It's why the industry went to vertical dropouts not long after.
In order to file the droputs to their full potential, I propped up the frame on its rear so that the dropout slots were vertical, then used a round file and oil. That let me just file downward. I checked my work frequently with a spare 10mm axle to make sure I was opening it wide enough, but maintaining a straight line along the top of the dropouts. Hope this helps.
My Diamondback came to me with partially-filled dropouts like this, although I don't think they were this bad. The idea, as I understand it, was to force the rear axle into a particular spot in relation to the rear derailleur for more consistent indexed-shifting performance. (Some bikes had plastic stops installed in regular horizontal dropouts to accomplish the same thing.) It's why the industry went to vertical dropouts not long after.
In order to file the droputs to their full potential
, I propped up the frame on its rear so that the dropout slots were vertical, then used a round file and oil. That let me just file downward. I checked my work frequently with a spare 10mm axle to make sure I was opening it wide enough, but maintaining a straight line along the top of the dropouts. Hope this helps.
10-26-21, 08:20 PM
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That would be only about 9.5mm, so you will need a flat file to take off another 0.5mm or so.
10-26-21, 08:21 PM
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10-26-21, 08:32 PM
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10-26-21, 08:37 PM
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10-26-21, 08:44 PM
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10-27-21, 06:06 AM
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Did you say if you are going to go fixed or single speed? If you did, I missed it. If single speed then the answer is to use a SS chain tensioner.
10-27-21, 07:25 AM
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10-27-21, 07:43 AM
#20
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I ordered a round file I hope will work. I m ight get lucky and only need to shave off a bit from each side. This dropout legitimately surprised me. I did a double take. It's an 84 Schwinn world sport mixte. Apparently they did not trust the ladies to adjust the position of the rear wheel.
Me? I'd scribe the line(s) above and below along the dropout opening, extending inward as far as a standard forged dropout would have. I'd scribe both the inside and the outside of the dropout. Then, I'd remove anything from the frame, leaving only the two triangles. That means no fork. (The reason is to remove any moment arm due to the imbalance of weight along the centerline when the frame is inverted and clamped.)
Then clamping the non-drive rear dropout at its rear curve, pointing upward, into a solid bench vise. Working downward, I'd begin removing material from the center portion to a depth of maybe 1/4 of the total needed. Then work outward to approaching the scribed lines, checking frequently that the tool is being held level as it works. No need to go to the scribed lines until you rotate the dropout in the vise. Check carefully as you go.
When the depth has been reached, rotate the frame so that the upper side of the dropout is clamped. This may require you to have the frame supported off of the bench surface (beneath the bench level) to hold the frame solidly in place. Again, but now using a flat file, remove material down to the scribed line. Work carefully and check the lines as you go. This side is the one that bears the load and aligns the wheel, so periodically test with your rear wheel to make certain that the axle sits perpendicular to the center plane of the frame. Adjust depth to get the wheel centered and plumb.
Flip the frame and work on the lower lip of the dropout. This one will be more subject breaking because it doesn't have the support of the frame brazed to it. Set the bottom bracket shell into the bench vise so that the rear triangle rests near the bench work surface. Using a drill press vise or something similar, clamp the lower lip of the dropout. Work on alignment carefully, so that your work is still downward toward the lower lip. Be patient.
As for tools, I'd use a Dremel or rotary tool with a cylindrical bit to remove much of the material. But I'd use hand files for the finishing work because they're easier to control.
Good luck.
Last edited by Phil_gretz; 10-27-21 at 07:47 AM.
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10-27-21, 07:20 PM
#21
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You will need to secure the rear dropout as you work on it. Do you have access to a solid bench vise? Doing this by hand while attempting to hold the frame with your non-working hand will make the job substantially more difficult and imprecise. Just a warning...
Me? I'd scribe the line(s) above and below along the dropout opening, extending inward as far as a standard forged dropout would have. I'd scribe both the inside and the outside of the dropout. Then, I'd remove anything from the frame, leaving only the two triangles. That means no fork. (The reason is to remove any moment arm due to the imbalance of weight along the centerline when the frame is inverted and clamped.)
Then clamping the non-drive rear dropout at its rear curve, pointing upward, into a solid bench vise. Working downward, I'd begin removing material from the center portion to a depth of maybe 1/4 of the total needed. Then work outward to approaching the scribed lines, checking frequently that the tool is being held level as it works. No need to go to the scribed lines until you rotate the dropout in the vise. Check carefully as you go.
When the depth has been reached, rotate the frame so that the upper side of the dropout is clamped. This may require you to have the frame supported off of the bench surface (beneath the bench level) to hold the frame solidly in place. Again, but now using a flat file, remove material down to the scribed line. Work carefully and check the lines as you go. This side is the one that bears the load and aligns the wheel, so periodically test with your rear wheel to make certain that the axle sits perpendicular to the center plane of the frame. Adjust depth to get the wheel centered and plumb.
Flip the frame and work on the lower lip of the dropout. This one will be more subject breaking because it doesn't have the support of the frame brazed to it. Set the bottom bracket shell into the bench vise so that the rear triangle rests near the bench work surface. Using a drill press vise or something similar, clamp the lower lip of the dropout. Work on alignment carefully, so that your work is still downward toward the lower lip. Be patient.
As for tools, I'd use a Dremel or rotary tool with a cylindrical bit to remove much of the material. But I'd use hand files for the finishing work because they're easier to control.
Good luck.
Me? I'd scribe the line(s) above and below along the dropout opening, extending inward as far as a standard forged dropout would have. I'd scribe both the inside and the outside of the dropout. Then, I'd remove anything from the frame, leaving only the two triangles. That means no fork. (The reason is to remove any moment arm due to the imbalance of weight along the centerline when the frame is inverted and clamped.)
Then clamping the non-drive rear dropout at its rear curve, pointing upward, into a solid bench vise. Working downward, I'd begin removing material from the center portion to a depth of maybe 1/4 of the total needed. Then work outward to approaching the scribed lines, checking frequently that the tool is being held level as it works. No need to go to the scribed lines until you rotate the dropout in the vise. Check carefully as you go.
When the depth has been reached, rotate the frame so that the upper side of the dropout is clamped. This may require you to have the frame supported off of the bench surface (beneath the bench level) to hold the frame solidly in place. Again, but now using a flat file, remove material down to the scribed line. Work carefully and check the lines as you go. This side is the one that bears the load and aligns the wheel, so periodically test with your rear wheel to make certain that the axle sits perpendicular to the center plane of the frame. Adjust depth to get the wheel centered and plumb.
Flip the frame and work on the lower lip of the dropout. This one will be more subject breaking because it doesn't have the support of the frame brazed to it. Set the bottom bracket shell into the bench vise so that the rear triangle rests near the bench work surface. Using a drill press vise or something similar, clamp the lower lip of the dropout. Work on alignment carefully, so that your work is still downward toward the lower lip. Be patient.
As for tools, I'd use a Dremel or rotary tool with a cylindrical bit to remove much of the material. But I'd use hand files for the finishing work because they're easier to control.
Good luck.
It's either going to get reshaped or thrown in the sea. I'll post some pictures of whatever happens.
12-04-21, 02:14 PM
#22
Senior Member
Dont know if you filed the dropouts, but I would drill a 10mm hole in the end of the dropout and just cut the remaining metal with a thin disc on an angle grinder, or if you dont have experience just use the side teeth of a flat file to remove the remaining metal.
04-11-22, 05:48 AM
#23
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Thread Starter
Sorry to resurrect an old thread but, just in case anyone was wondering, this worked. I used a 10mm round file and a regular flat file and did it in about an hour.
They look a little oversized in the picture because I kept filing, trying to correct what I thought was uneven dropouts but which turned it to be a bent frame. The frame is in the garbage now for that reason but would've worked fine.
They look a little oversized in the picture because I kept filing, trying to correct what I thought was uneven dropouts but which turned it to be a bent frame. The frame is in the garbage now for that reason but would've worked fine.
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04-12-22, 03:50 AM
#24
Newbie
I'd drill a 10mm hole at the back of the dropout, make appropriate cuts with a cutoff disc/angle grinder, then clean up with a flat file.
ETA: never mind, see you got it done. glad it worked
ETA: never mind, see you got it done. glad it worked
