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Can I safely cut a deeper dropout?

Old 09-08-19, 07:27 AM
  #1  
bedtime
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Can I safely cut a deeper dropout?

I'd like to cut a portion out of my dropout. The reason is that I want the tire to be more in line with the fork and handlebars. This will help with many of the artistic cycling tricks I plan to do.

To save me describing such tricks and derailing the thread, you can check out a post I made on the subject: https://www.bikeforums.net/alt-bike-...ng-anyone.html

I'm guessing I could either hacksaw or drill the dropout—not sure which one is best. Below is a picture of where I want to cut:



My question is how to best do this, and do you think the dropout will be able to sustain a reasonable amount of strength and not just crack or crumble in some way due to the cutting?

Here is some info on the fork: Hi-ten steel with 11/4-inch OD legs, 11/8-inch threadless steerer, and 6-millimeter dropouts.

I don't do any hopping, jumping, or falling tricks. The riding is generally light, and my weight is 150lbs.

Will this be doable?

Last edited by bedtime; 09-08-19 at 07:31 AM. Reason: Changed saw to hacksaw
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Old 09-08-19, 08:24 AM
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I don't know the exact angle that you are after but would it not be better to remove the drop if it is stamped steel and reverse it...that would move the wheel axis further in shortening the wheelbase etc.
Any professional welder could do this...if you try drilling it on your own you will need to be very precise...otherwise, the front wheel will be out of alignment and throw of your balance defeating the purpose etc.
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Old 09-08-19, 08:50 AM
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Originally Posted by xiaoman1 View Post
I don't know the exact angle that you are after but would it not be better to remove the drop if it is stamped steel and reverse it...that would move the wheel axis further in shortening the wheelbase etc.
Any professional welder could do this...if you try drilling it on your own you will need to be very precise...otherwise, the front wheel will be out of alignment and throw of your balance defeating the purpose etc.
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The bike below is what I'd like to somewhat replicate. I know I'll likely not achieve the head tube angle, but the procedure will steepen it as the wheel lifts further into the dropout causing the frame to lower. This will also bring the two tires closer together, which is what I also want.



The tricks I'd like to do require that the handlebars be balanced with the forks and tire; grabbing the bars and spinning ones body around the bike on an imbalanced system wouldn't work too well. You should be able to draw a line from where the handlebars attach, through the stem, into the forks, and into the tire. It all needs to be as in line as possible. That is the most important thing.

I've ordered a special 90 deg. handlebar stem (e.g., stem stands straight up in line with forks) to take of handlebar/stem balance.

As to the welding suggestion, I don't fully gather what you're saying. Could you break it down a little? You don't just mean flipping the entire fork backwards, do you?

Last edited by bedtime; 09-08-19 at 08:53 AM. Reason: Answered another question.
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Old 09-08-19, 09:35 AM
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Flipping the fork might be one way....it would depend on the rake etc.
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Old 09-08-19, 10:21 AM
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Originally Posted by xiaoman1 View Post
Flipping the fork might be one way....it would depend on the rake etc.
I tried flipping the fork, and it just offsets the wheel/fork balance backwards instead of forwards.
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Old 09-08-19, 10:26 AM
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As far as the safety of cutting the drop-out, no one in their right mind will tell you "no problem, give it a try". I would point out that (IMHO) you are using a normal bike for an unusual use (artistic bicycling) and this may put more than normal forces on the front fork (as in jumping from the seat onto the fork with both feet), so you probably need a stronger fork than normal. I recommend not doing this, and getting a fork designed and built for use.

But "Man's reach should exceed his grasp, else what's a heaven for?".

So I understand your original question as: "Will cutting this slot end up hurting the metal in or the structure of the dropout?" there are a couple of things to consider. The first is geometry. Cutting the slot at the angle you show will move the wheel back, but also up, so the front of the frame will drop. May not be a big deal, but you are going for a very responsive ("twitchy") bike, and this drop may have an effect. Consider this in your modification plans. If you cut the additional slot straight back (so that the axle slot was a doglog shape) you'd keep the front elevated. I suspect that you could cut a bit of metal out of the slot provided you left enough metal in the gullet so that your axle nuts tighten onto the dropout and don't touch the fork tubes. That may not allow you much cutting space (so is the view worth the climb?). But before you start, remember you have to stop cutting the slot to leave enough space for the nut, with (for example) 1/16" or 1.5mm clearance or so FROM THE WELD. Check both sides of the dropout, as he welding may be thicker on the inside or outside. You don't want a nut to tighten on the weld. (Frankly, I suspect that if you measure how much clearance you have right now, you'll be surprised at how little you'll be free to cut.

This then leaves the effects on the metal. Your dropout is welded. I don't know the alloy. The safest way to cut the new slots would be to lay out your slot with a sharp scribe, then clamp the dropout in a vice and use rat-tail and flat files to remove the metal. Done carefully and finishing with a an appropriately file (smooth, or perhaps bastard if you have a light hand) you won't mork up the metal. Welding in new dropouts is beyond my tech expertise, but a good welder can do this is its possible to ascertain the alloy that your fork is made of.

But, first thing, check out how much clearance you have from the current nut or washer to the border of the weld. And whatever your plans, make sure that they end up having the nut and washer on flat dropout, and not on the border of the weld bead.
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Old 09-08-19, 10:27 AM
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Originally Posted by bedtime View Post
I tried flipping the fork, and it just offsets the wheel/fork balance backwards instead of forwards.
Isn't that what you want the slot to do?

Ah, upon edit, and in watching the amazing video you cited, I see the issue: when you are standing on the handlebars you need to be able to do a quick 180 turn and have the wheel have the same alignment in either case. I see no way to do this with slotting the dropout. As outlined above, you could cut the dropouts off, cut the fork tube ends off appropriately, and then weld on new dropouts that give you the proper zero-offset design, with enough allowance of space between the fork/dropout weld and the the axle nut/washer/locknut.

I have to say that seeing the gal back up her bike was just amazing to me. The forum post that bedtime cited, contains a pretty amazing video of a gal doing some impressive tricks of balance and strength on a bike. I thought it was interesting:

https://www.bikeforums.net/alt-bike-...ng-anyone.html

And another one:


Last edited by WizardOfBoz; 09-08-19 at 10:41 AM.
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Old 09-08-19, 12:08 PM
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No problem, give it a try. What do you have to loose? Start with a hacksaw.
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Old 09-08-19, 01:24 PM
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The YouTube video of artistic cycling in your other thread blew my mind. It's worth a watch for anyone even remotely interested in cycling (all of us!).

It looks like these bikes require the front axle to be directly inline with the fork's steerer tube (essentially, zero offset). This will be very difficult to achieve with an off-the-shelf fork, because that offset is needed to generate enough trail for stable riding, and forks are designed accordingly. Some forks have legs that curve forward and some forks have straight legs that angle forward. If your fork legs angle forward at all (from the centerline of the steerer), you may not be able to align the axle with the steerer, even if you could cut the dropout deep enough. In that situation, you'd theoretically want the axle behind the fork legs, so as to achieve that zero offset you want. From that respect, you could actually try to find a straight-legged fork that angles forward, and have dropouts welded to the rear of the legs (as they would normally be installed). You could then cut dropout slots as needed to position the axle directly in line with the steerer.

I'm not qualified to speak to issues of strength or geometry of your proposed modification to the fork, but I think I would get it done with a Dremel or similar. Use any number of special abrading drums with the correct material (they probably have some designed for strong metal). You would basically just "dig" the dropout deeper. Keep in mind that you won't be able to go ALL the way back to the tube of the fork leg because the axle lock nuts will need some room.
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Old 09-08-19, 01:32 PM
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My favourite artistic cyclist, especially considering that this performance happened over 55 years ago:

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Old 09-08-19, 02:26 PM
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The first is geometry. Cutting the slot at the angle you show will move the wheel back, but also up, so the front of the frame will drop. May not be a big deal, but you are going for a very responsive ("twitchy") bike, and this drop may have an effect.
Yes, I am going for 'twitchy' and responsive, and the result was just that; I found riding with no hands to be more twitchy, but I soon was able to attain good balance. This certainly forces you to do so!

But before you start, remember you have to stop cutting the slot to leave enough space for the nut, with (for example) 1/16" or 1.5mm clearance or so FROM THE WELD.
I did this exactly as you said. A miracle happened and the tire has turned out to be very centered. It's ever so slightly to the left, but I can fix that will a little filing when I'm up to it. Also, the gap between the tire and the fork has decreased, allowing for stopping by foot without your foot getting stuck into the forks when you jam it in there:





Done carefully and finishing with a an appropriately file (smooth, or perhaps bastard if you have a light hand) you won't mork up the metal.
This was awesome advice. I ended up buying a bastard rat-tail file. Boy was that EVER a workout! I took the bike and tools to the skate park and filed the dropouts down. It took maybe 90 minutes of filing 80% of the time to get the metal down to where I needed it. The big issue was I didn't have anything to securely hold the bike, such as a vice, so I couldn't use both hands on the vice, as my other hand was needed to hold the bike steady. My right hand has a fully open blister.

I have to say that seeing the gal back up her bike was just amazing to me. The forum post that bedtime cited, contains a pretty amazing video of a gal doing some impressive tricks of balance and strength on a bike. I thought it was interesting:
When I first got my BMX a month or two ago I was into BMX street riding, then BMX flatland shortly after, and once I saw artistic cycling (somewhat by fluke), I knew that was the one for me; it's just so graceful and fun to watch and do. So, I am spreading the word here a little in hopes that an 'Indoor cycling' forum could be added for artistic cycling, cycleball, and other niche indoor cycling activities/sports.

Here is one of my favorite videos:


No problem, give it a try. What do you have to loose? Start with a hacksaw.
Yep, got it done as soon as I grabbed the file.

The YouTube video of artistic cycling in your other thread blew my mind. It's worth a watch for anyone even remotely interested in cycling (all of us!).
I'm glad you think so. Many people here seem to think that posting about this sport is spam. How? It is cycling. It is an official sport with rules and competitions. People might just like it. Nothing is being sold except the idea. And some people might want to do tricks but not dig the pounding and grinding of regular BMX, or the style of flatland. They may want something a little more graceful. Artistic cycling fills that gap very well.

From that respect, you could actually try to find a straight-legged fork that angles forward, and have dropouts welded to the rear of the legs (as they would normally be installed). You could then cut dropout slots as needed to position the axle directly in line with the steerer.
It's done to my satisfaction for now, and I don't want to get into paying anyone to weld it, as I just don't have the money ATM. I was however thinking of filing the read dropout to lift the tire and at the same time bring it forward. This will allow for a shorter chain, tighter turn, and increased 'twitchyness'.

My favourite artistic cyclist, especially considering that this performance happened over 55 years ago:
Those bikes (or close to them) are actually available today. Generally they consist of two unicycles joined together. Would love to have her bike, though. Looks like a lot of fun!
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Old 09-08-19, 03:14 PM
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Originally Posted by bedtime View Post
Those bikes (or close to them) are actually available today. Generally they consist of two unicycles joined together. Would love to have her bike, though. Looks like a lot of fun!
Of course they are, they are the specific types of bicycles used for artistic cycling. They have been used for over 60 years
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Old 09-08-19, 04:37 PM
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[QUOTE=WizardOfBoz;21113147]As far as the safety of cutting the drop-out, no one in their right mind will tell you "no problem, give it a try". I would point out that (IMHO) you are using a normal bike for an unusual use (artistic bicycling) and this may put more than normal forces on the front fork (as in jumping from the seat onto the fork with both feet), so you probably need a stronger fork than normal. I recommend not doing this, and getting a fork designed and built for use.

+1 To all of the above and that is why a pro should look at it and give you an assessment, I would not drillit or cut it unless I was very proficient with the tools etc....if removing and changing the drop (don't just cut and reweld..work with the slot in the fork if it is brazed) however if the drop is just tig/mig welded a builder could remove and reposition providing you have enough clearance and the angles are correct for your application.
You may find that you will have to put additional reinforcement in the form of a gusset to strengthen the drop as well as the fork etc.
"Careful" measurement and "not" overheating the metal are keys to proper set-up.
Good Luck, Ben
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Old 09-08-19, 04:38 PM
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[QUOTE=WizardOfBoz;21113147]As far as the safety of cutting the drop-out, no one in their right mind will tell you "no problem, give it a try". I would point out that (IMHO) you are using a normal bike for an unusual use (artistic bicycling) and this may put more than normal forces on the front fork (as in jumping from the seat onto the fork with both feet), so you probably need a stronger fork than normal. I recommend not doing this, and getting a fork designed and built for use.

I see you seem to have solved the problem already with expertise and tools at hand..Best. Ben

+1 To all of the above and that is why a pro should look at it and give you an assessment, I would not drillit or cut it unless I was very proficient with the tools etc....if removing and changing the drop (don't just cut and reweld..work with the slot in the fork if it is brazed) however if the drop is just tig/mig welded a builder could remove and reposition providing you have enough clearance and the angles are correct for your application.
You may find that you will have to put additional reinforcement in the form of a gusset to strengthen the drop as well as the fork etc.
"Careful" measurement and "not" overheating the metal are keys to proper set-up.
Good Luck, Ben
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