# Dropouts modification



## Charly-Hank (Apr 27, 2017)

Hello frame builders , I could use some of your advice here.
I 'd like to install an alfine 8 gear hub on my carbon frame but the issue is the dropouts are closed.

View attachment 1134260
View attachment 1134300








Do you think I can cut a way for the alfine axle without weakening the frame ?

Or should I use some kind of adaptator like roadtopista or the Orange P7 ones instead ?
View attachment 1134262








Any idea ?


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## m-gineering (Feb 5, 2012)

Charly-Hank said:


> Do you think I can cut a way for the alfine axle without weakening the frame ?
> 
> Any idea ?


It's not a question of getting the axle in the frame, you have also to consider how you are going to counteract the torque the hubgear puts on the axle washers. Next you have to figure out how to tension the chain. 
By that point a derailleur will be very attractive!


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## Charly-Hank (Apr 27, 2017)

Thank you for the prompt answer.



m-gineering said:


> how you are going to counteract the torque the hubgear puts on the axle washers.


Could you explain what I need to do please ? I don't know much in this domain. 
Is this the kind of issue you believe I could encounter ? :








Are the adaptators a better solution ?

Concerning the way I will tension the chain (or the belt perhaps), I will use a pf30 eccentric bottom bracket.

I ride a commuter everyday and I love my alfine 8.
I know it sounds like a blasphemy for some of mtb riders but I really want to get rid of the derailleur.


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## Velobike (Jun 23, 2007)

The simple answer is to use a Magic Ratio.

All you need to do is to find the set of chainring and rear sprocket that give you the right amount of chain.

I have been using this successfully on a fatbike for a few years now.

Couple of provisos. Use singlespeed chainrings, preferably of steel because that wears slower, and so your chain won't go slack as quickly. It's also best to use single speed chain because it can tolerate a lot more slack without jumping off the sprockets.

Alfine rear cogs are inexpensive, so have a few on hand of different sizes until you find a match. Eg if I was looking at wanting to use a 32 front and a 20 tooth rear, I would also have a 19 and a 21 on hand for the rear, and a 32 and a 33 for the front. Also having a couple of used chains around can be useful too because a slight amount of wear may make the chain just right.

You may not get the exact ratio you were looking for, but you'll get close, which is good enough because you have gears in the rear hub.

Google magic ratio, there's plenty formulas for calculating the ideal set up, but I just use a bit of trial and error.

Whatever you do, don't force the wheel in to the dropout with an almost right set up that leaves the chain in high tension. You'll wreck your bearings.

A bit of slack is no problem with proper chain and rings.

As mentioned above by m-gineering, some means of countering the torque reaction is needed. Looking at the pic of your frame, I'm not clear - is that all there is, or are there dropouts that get bolted in?

Anything is better than using a tensioner.


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## Charly-Hank (Apr 27, 2017)

A lot of quality informations here, thank you very much .
I was considering installing a Gates Carbon drive as I have an elevated chainstay.
On their website, you can calculate the ratio : Gates&#0174 Carbon Drive&#0153 Bicycle Calculator

The derailleur hanger is actually missing on the picture, it was bolted in.
The axle just fit in the holes, it is a 27.5+" and 29" frame (WCB-M-078 27.5+/ 29 /29+-workswellbikes)
I've also find an article about Internal-Gear Hub Torque, so I'll study this.

But the question does not apply if I can't get the alfine hub in the frame.

How should I proceed ? Cut the frame or use adaptators ?


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## cyclingengr (Dec 22, 2014)

I would not recommend cutting the frame unless you want to add a bunch of reinforcement to the frame. Have you fabricated anything out of carbon fiber before? If Alfine does not come in through axle, you are probably out of luck on that frame.


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## m-gineering (Feb 5, 2012)

A gates belt needs exact alignment and a very stiff rear triangle. 'Somebody's ' elevated chainstay is not a good starting point. 

You could perhaps design dropouts to take the hub and bolting to the existing holes, but getting things lined up with the diskbrake mount is another challenge.


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## Charly-Hank (Apr 27, 2017)

Thank you for all the leads, I will give all that a thought.

I was thinking of something else.
What if I cut the alfine's axle and use these kind of nut with inner thread ?


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## thefuzzbl (Jul 5, 2006)

I think rohloff comes in thru axle now and you can get an adapter for postmount brakes. You should get one of those. Or a different frame. Modifying your frame for alfine will be nearly impossible because A) You will likely damage the frame beyond repair trying to modify it and B) you still have no way to arrest the rotation of the axle. Alfine uses keyed washers that fit into the dropout slots. You wont have that unless you replace the whole dropout and that just wont work well. 

So again, Rohloff hub or new frame. And I would recommend using a PF30 EBB as long as your carbon frame can handle it (most cannot) because itll work better than a magic gear and you will be able to adjust it.


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## Charly-Hank (Apr 27, 2017)

I will not cut my frame, it seems too crazy. So thank you for bringing me back to the reason.
I'll try to cut the alfine axle instead and use nuts as showed above.
Concerning the anti rotation washer I think I can find a solution . I could maybe fit it inside, in the place of the hanger, or maybe make a custom one .
I could at least give it a shot ...
My frame can actually handle pf30 EBB.
Thank you.


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## Velobike (Jun 23, 2007)

Charly-Hank said:


> Thank you for all the leads, I will give all that a thought.
> 
> I was thinking of something else.
> What if I cut the alfine's axle and use these kind of nut with inner thread ?
> View attachment 1134389


You may have a problem getting a nut like that with the right threading for the Alfine.

I'm pretty sure the thread on my Alfine is the same as my old Sturmey-Archer, so likely an old British standard. If you have access to a lathe you could turn up your own - probably 26tpi and ⅜". (I could check but it would mean loosening the wheel on my bike and it's a right faff getting it properly aligned)

Plus you still have the problem of antirotation. It is necessary on 2 counts. Firstly to protect the hub and frame from damage and needs to be secured on both sides, and secondly, it determines the position of the cable feed into the change mechanism.


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## Charly-Hank (Apr 27, 2017)

You are right, finding deez nutz is a problem of it's own !
3/8 26tpi as you wrote.


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## mickuk (Jul 6, 2007)

Make new bolt on plate dropouts like the orange ones (underslung below the existing carbon dropout), but with a horizontal axle slot and obviously no mech hanger. 

That runs with regular alfine nuts and anti turn washers which also sorts chain tensioning without eccentric. Might need to work out magic ratio / chain length / chainstay length to allow it to work if you have a fixed disc mount position. 

Then run a non plus 27 rear wheel to keep bb height and angles somewhere normal ish.


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## Charly-Hank (Apr 27, 2017)

I'm not conviced by this solution because it would steepen the geometry a lot and alignment would be complicated.
The thing that made me think it could be possible to cut the frame, is the fact that the rear triangle on the drive side is very thin (4 mm) and full of holes . One of them is really close to the edge (2 mm). The distance between this hole and the axle is 3 mm :







I can't see how 5 mm of carbon can make such a difference but I'm here to learn from people who know. 
I will visit a carbon repair shop tomorow and hear what he has to says .
It looks like a dead end ...


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## m-gineering (Feb 5, 2012)

thefuzzbl said:


> I think rohloff comes in thru axle now


Not really, Rohloff offers a bodge so you can fit a Rohloff hub to a thru-axle frame. But is a pretty horrible solution (you're supposed to buy new Nordlock washers every few times you unbolt (M7, Yuk) the rear wheel) so I'd try to avoid it if at all possible.


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## bsieb (Aug 23, 2003)

Get a set of horizontal dropouts to fit your frame. Try it, don't overthink the effect on geometry. Or get a new frame. You need dropouts of some kind. 

edit: I run Alifine 8 myself, like it, but it's a little antiquated for modern rear axles, especially those anti-rotation washers. You can get tug nuts that are slotted for the Alfine axle, but I don't know that they would do you any good either.


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## Charly-Hank (Apr 27, 2017)

Will a fork with more travel and an EBB be sufficient to correct the effect of the dropouts on the geometry ?

I will certainly have to make them machined to measure .
what material should they be made of ?
I am also concerned by the thickness on the drive side (4 milimeters) . Won't they apply more stress to the frame ?


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## Eric Malcolm (Dec 18, 2011)

Personally, I think that the 2 larger holes are too close together to add plates. They really need to be further apart. A rocking motion will destroy this rear end. Plates can be made out of alloy. But, you need to check the hub spacing. No good trying to fit a 120mm hub into a 140mm plus spaced rear end scenario.

Eric


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## Charly-Hank (Apr 27, 2017)

the hub is actually 135mm wide.


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## Eric Malcolm (Dec 18, 2011)

Charly-Hank said:


> the hub is actually 135mm wide.


And if you put say a 6mm thick plate on the inside of the dropouts, will the resulting 12mm total reduce the space down to 135mm? This is how you have to think if you want to find your solution. The bigger problem you face is with the spacing of those 2 mount holes. They will be the cause of grief for you. Yes, you could make plates to fit, it will look initially nice, but you need to heed the caution being offered here, there is not enough spacing between bolts. Go study the options that we builders have to use and you will see that every option made has wider spacing. There is a reason for this.

Eric


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## Charly-Hank (Apr 27, 2017)

I am not enthousiastic about the idea of adding plates. The holes seem too close from each other indeed.

The carbon repair shop do not do modifications.

Cutting 8 mm of one side of the axle could allow me to insert the axle in one hole and slide the other one in the second .
Looks like the best option so far.


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