Dropout Repairs - Old Fashioned Engineering...

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boblo
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Joined: 24 Sep 2009, 7:35pm

Dropout Repairs - Old Fashioned Engineering...

Post by boblo »

I have a plastic bike with aluminium dropouts. Over the years, the front of the driveside and the rear of the non drive side have worn a bit so the wheel can sit a bit squiffy within the chain stays. Even with the QR's well tightened, the wheel can 'pull' over under the immense load of my Amazonian thighs...

I wondering about a bit of remedial work by a proper bicycle engineering company (rather than a shifter of Taiwan derived boxes...). I'm thinking of some sort of machined adapter or weld plus machining. I'd want to minimise damage to the carbon and paint so I may be asking too much.

Any experiences in fixing this and/or recommendations for pukka cycle engineering companies please? The grubbier and oilier the better as these tend to be a better bet.
Last edited by boblo on 8 May 2021, 9:24am, edited 3 times in total.
fastpedaller
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Joined: 10 Jul 2014, 1:12pm
Location: Norfolk

Re: Dropout Repairs - Old Fashioned Engineering...

Post by fastpedaller »

I'd suggest that the ideal 'fix' would be to machine the dropout slightly larger, and then 'face' it with steel to minimise wear - like the 'anti-bite guard' idea which is used on alloy freehub bodies. it'll probably be cheaper to buy a new frame.
boblo
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Joined: 24 Sep 2009, 7:35pm

Re: Dropout Repairs - Old Fashioned Engineering...

Post by boblo »

Aye, the throwaway society... A new frame is going to be ~£4k so am inclined to explore options. Cost is not the chief criteria as I like the frame, it's an old friend, new frames aren't that easy to come by and mine is Q/R and rim braked so obsolescent which makes getting a decent like for like replacement more difficult.
Jdsk
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Joined: 5 Mar 2019, 5:42pm

Re: Dropout Repairs - Old Fashioned Engineering...

Post by Jdsk »

Can you add some photos?

Would it be possible to extend the area over which the dropouts engage with the frame? That might allow more design options.

It doesn't have to be local. There's now a flourishing trade in machining to online orders. That can start either with a rough sketch and they do the CAD/ whatever and the metalwork, or you supply the CAD and they work to that.

Jonathan
boblo
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Joined: 24 Sep 2009, 7:35pm

Re: Dropout Repairs - Old Fashioned Engineering...

Post by boblo »

@jdsk

The wear is very minor and hard to see. I think ~0.5mm each face but over the radius of the wheel, this puts alignment between the chain stays out by ~10mm. A lot on a close clearance road bike. The dropouts are obv vertical, forgot to mention that...
Jdsk
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Re: Dropout Repairs - Old Fashioned Engineering...

Post by Jdsk »

My thinking was that photos would inform the remedial options, rather than illustrate the wear...

Jonathan
iandusud
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Joined: 26 Mar 2018, 1:35pm

Re: Dropout Repairs - Old Fashioned Engineering...

Post by iandusud »

You've probably addressed this but bhat sort of QR are you using? Some are much better than others, I've used QR with fixed gear in horizontal drop outs without any issues.
boblo
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Re: Dropout Repairs - Old Fashioned Engineering...

Post by boblo »

iandusud wrote: 8 May 2021, 11:12am You've probably addressed this but bhat sort of QR are you using? Some are much better than others, I've used QR with fixed gear in horizontal drop outs without any issues.
Aye. I was running Mavic's own which is a lightweight, external cam design. Switched to Shimano via Hope and they don't seem to make a lot of difference. Plenty of tension so probs not that.

I'll post some pics up in a bit.

Thanks all for your help.
alexnharvey
Posts: 1921
Joined: 10 Jan 2014, 8:39am

Re: Dropout Repairs - Old Fashioned Engineering...

Post by alexnharvey »

fastpedaller wrote: 8 May 2021, 9:18am I'd suggest that the ideal 'fix' would be to machine the dropout slightly larger, and then 'face' it with steel to minimise wear - like the 'anti-bite guard' idea which is used on alloy freehub bodies. it'll probably be cheaper to buy a new frame.
Agree with the first part but not the latter. A small shim of stainless steel in 0.5mm would be relatively easy to cut and bend. Since it is mostly seeing a compressive force a good epoxy or methacrylate glue should hold it.
Jdsk
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Re: Dropout Repairs - Old Fashioned Engineering...

Post by Jdsk »

alexnharvey wrote: 8 May 2021, 12:31pm
fastpedaller wrote: 8 May 2021, 9:18am I'd suggest that the ideal 'fix' would be to machine the dropout slightly larger, and then 'face' it with steel to minimise wear - like the 'anti-bite guard' idea which is used on alloy freehub bodies. it'll probably be cheaper to buy a new frame.
Agree with the first part but not the latter. A small shim of stainless steel in 0.5mm would be relatively easy to cut and bend. Since it is mostly seeing a compressive force a good epoxy or methacrylate glue should hold it.
Yes, I'd be looking for compression rather than only injecting the load through the edge, and possibly using a larger area than the original.

Jonathan
jimlews
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Joined: 11 Jun 2015, 8:36pm
Location: Not the end of the world.

Re: Dropout Repairs - Old Fashioned Engineering...

Post by jimlews »

Perhaps a sleeve over the end of the axle?
I.D. just enough to 'engage' the axle thread. O.D just enough to fill the gap.
Know anyone with a lathe?
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531colin
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Re: Dropout Repairs - Old Fashioned Engineering...

Post by 531colin »

alexnharvey wrote: 8 May 2021, 12:31pm
fastpedaller wrote: 8 May 2021, 9:18am I'd suggest that the ideal 'fix' would be to machine the dropout slightly larger, and then 'face' it with steel to minimise wear - like the 'anti-bite guard' idea which is used on alloy freehub bodies. it'll probably be cheaper to buy a new frame.
Agree with the first part but not the latter. A small shim of stainless steel in 0.5mm would be relatively easy to cut and bend. Since it is mostly seeing a compressive force a good epoxy or methacrylate glue should hold it.
This sounds OK to me.
File out the dropout slots so when they are suitably shimmed the wheel sits central.
You can get stainless tube 10mm ID, 12mm OD ; bits of that would make ideal dropout liners, I should think.
https://www.ebay.co.uk/itm/402292859221 ... d586dc7e1f
....or maybe (as above) little sleeves to put over the axle, just less than the width of the dropout.
fastpedaller
Posts: 3433
Joined: 10 Jul 2014, 1:12pm
Location: Norfolk

Re: Dropout Repairs - Old Fashioned Engineering...

Post by fastpedaller »

alexnharvey wrote: 8 May 2021, 12:31pm
fastpedaller wrote: 8 May 2021, 9:18am I'd suggest that the ideal 'fix' would be to machine the dropout slightly larger, and then 'face' it with steel to minimise wear - like the 'anti-bite guard' idea which is used on alloy freehub bodies. it'll probably be cheaper to buy a new frame.
Agree with the first part but not the latter. A small shim of stainless steel in 0.5mm would be relatively easy to cut and bend. Since it is mostly seeing a compressive force a good epoxy or methacrylate glue should hold it.
That was my logic as well. I didn't realise the frame was £4k!
fastpedaller
Posts: 3433
Joined: 10 Jul 2014, 1:12pm
Location: Norfolk

Re: Dropout Repairs - Old Fashioned Engineering...

Post by fastpedaller »

Jdsk wrote: 8 May 2021, 12:39pm
alexnharvey wrote: 8 May 2021, 12:31pm
fastpedaller wrote: 8 May 2021, 9:18am I'd suggest that the ideal 'fix' would be to machine the dropout slightly larger, and then 'face' it with steel to minimise wear - like the 'anti-bite guard' idea which is used on alloy freehub bodies. it'll probably be cheaper to buy a new frame.
Agree with the first part but not the latter. A small shim of stainless steel in 0.5mm would be relatively easy to cut and bend. Since it is mostly seeing a compressive force a good epoxy or methacrylate glue should hold it.
Yes, I'd be looking for compression rather than only injecting the load through the edge, and possibly using a larger area than the original.

Jonathan
It was the 'idea' of the anti-bite guard that I was referring to ie a 'harder surface' I wasn't envisaging just the edge, but exactly as alex explained it (better than I did :oops: )
jo' bo
Posts: 121
Joined: 8 May 2021, 8:21pm

Re: Dropout Repairs - Old Fashioned Engineering...

Post by jo' bo »

boblo wrote: 8 May 2021, 9:07am I have a plastic bike with aluminium dropouts. Over the years, the front of the driveside and the rear of the non drive side have worn a bit so the wheel can sit a bit squiffy within the chain stays. Even with the QR's well tightened, the wheel can 'pull' over under the immense load of my Amazonian thighs...

I wondering about a bit of remedial work by a proper bicycle engineering company (rather than a shifter of Taiwan derived boxes...). I'm thinking of some sort of machined adapter or weld plus machining. I'd want to minimise damage to the carbon and paint so I may be asking too much.

Any experiences in fixing this and/or recommendations for pukka cycle engineering companies please? The grubbier and oilier the better as these tend to be a better bet.
If you want old fashioned engineering, then shim it with precision shims. These are readily available in a variety of sizes,in the form of car feelers gauges

Cut them up, find the one that's the correct thickness then glue it in place so it doesnt fall out when you take the wheel off.

I've fixed multiple worn suspension fork drop outs this way
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