I am a frame builder AMA

Which cranks?

If it is the arms on both sides are not clearing the chainstays I would replace the stays.
They can be reused for something else with longer dropouts later on.

If it is the chainrings I would cut out a bit of drive side chainstay and make a yoke from a bit of flatbar

Or get cranks with wider q-factor

Specialized S-works carbon. Non-negotiable though.

If it is the arms on both sides are not clearing

It is.

the chainstays I would replace the stays.

Bugger. I was afraid someone would say that. Trouble is, my framebuilding fixture isn't ready yet. By a long way.

Ah. I was going to suggest something like Cannondale SiSL2.

If it is the chainrings I would cut out a bit of drive side chainstay and make a yoke from a bit of flatbar

The inner chainring requires a very minor dimple. Not really a fan of flat plate yokes, unless absolutely necessary. Goes against the 'vertical compliance with lateral rigidity' mantra. Plus fugly.

I've got other cranksets I could use, including a Cannondale SISL non-2. But I've also got the S-Works crankset with a Quarq PM and they won't work on the next few frames I've got planned, so they're going on this bike come hell or high water.

E-stay?

Been there, done that, not going there again. It's a solution to a problem which results in problems bigger than the problem you were trying to solve in the first place.

Hello,

Can anyone send me a 3d model of a pinion gearbox?

Kind Regards,

jim

Anyone got any opinions on this,

I decided to use Columbus cx bend chain stays in order to get the tyre and chain ring clearance I need on this large tyre fixed frame in building for my mate.

Because of the bend in the stays, when inserted into the ports in the bb shell they want to sit very close together at the wheel end.

It’s easy enough to pull them out to where I need them (120mm spacing) but they do start to pull away from the tangs on the ports on the bb shell.

So I’m not sure if I should braze the stays in where they have good contact with the bb lug then cold set them to where I need or hold the ends out where I need them and deal with the gap before/during brazing?

I’ve tried coercing the ports a bit but they just want to bend at the ends of the tangs, not take on a proper ‘set’.

These photos show the stays inserted to the ports and sitting narrow. Getting good contact with the lug.

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And with the end pulled out to 120mm you can see the stays start to come away from the tangs on the inside.

Thinking if I’m holding the ends out where I need them before brazing then it might be better to use brass as it’ll fill the gaps better? Suspect it’d still need some cold setting too.

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Can’t you pull the lugs over too?
Some gentle hammering

With a drift, from the inside? I tried pulling them over with an adjustable spanner closed down on them yesterday and like I say, was difficult to do much more that bend the ends. Will give it a go with a hammer today.

The inner tangs. Just to close them down onto the tube

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Yup, got you.

It’s just gonna be trying to keep them flat rather than kink in the middle which is what I was getting yesterday.

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Or a slight squash with a clamp

@dangeek @PhilDAS between drifts, clamps, blocks of wood, wooden file handles and a spare stay to pull the sockets where I wanted them I got it all done today.

Also got a chance to try out my hydraulic dimpler to create a little more room for the crank arm spider.

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my hydraulic dimpler

Have I missed the details of this somewhere? If not, details please. I'm about to make my own chainstay dimpling tool. I was going to go with a boring old screw thread for pressure, but hydraulic sounds appealingly over-engineered...

Nice one. There's always a way.

Is your dimpler made from a crimper? Good idea.
https://www.youtube.com/watch?v=G1SBQ1udYno

As @dangeek suggests, its a hydraulic crimper, for attaching terminals to battery leads etc.

It comes with a bunch of different size dies, one of which I filed down to make the bit that does the dimple, I also brazed a little stud (thats how the 'bits' locate into the whole thing) into a bit of rectangular steel bar then wrapped that in innertube in order to spread the load along the back of the stay.

Could probably do with a longer dimple former bit as I had to take a few stabs at it and it's a little bit rippled but it'll be fine.

Plug type fork ends: are they all similar dimensions? I have a fork on my road bike which I like, but is a bit short (364mm axle to crown, so the pads on a short drop road caliper are at the top of their adjustment range). I'd like to lengthen the fork by about 5mm. I thought maybe an option would be to braze in new fork ends (currently it has plate type ends brazed in).

A related question: what's the practical maximum axle to crown length for short drop road calipers? I've commonly seen 367mm, and the most I've seen is 369.5mm.

Side note: the bike's handling is a bit quick for my tastes now, so slackening the head angle by up to (say) 0.5 degrees is fine.

Plug type fork ends: are they all similar dimensions?

Nope, lots of different plug sizes.

Also, I can’t imagine how you would be able to remove plate your dropouts, trim the legs down (up) to remove the slotted area and end up with a longer a2c.

Cheers, good to know.

I'd assumed removing the plate drops with heat, then putting the plugs straight in and buttering some braze into the gaps. Possibly just easier to replace fork blades entirely.