Road Gear

Technical FAQ: Aligning derailleur hangers, silk tubular memories

Lennard Zinn runs through the options on how to straighten a derailleur hanger and provides advice on shifting and derailleur set-up.

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Dear Lennard,
Just watched your video on realigning a derailleur hanger. I’ve just bought an old Peugeot and the socket for the derailleur bolt (which is part of the frame) is WAY out of alignment; in other words, it’s bent. Would using a crescent wrench get it back into alignment, as shown in your video? Your video looked as if it was covering hangers that are fitted to the bike, that’s why I’m asking.
— Geoff

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Dear Geoff,
Yes, the hanger-alignment process is the same whether it is a bolt-on derailleur hanger or one that is cast or machined as a single unit with the dropout. That said, if the hanger is so bent that the threaded hole in the hanger is ovalized, then bending the hanger straighter with a Crescent wrench will likely be insufficient in and of itself, because the derailleur mounting bolt won’t thread into the hole; you would still need to tap the threads.

And be clear that it is pretty tough to properly align a badly-bent steel hanger with a Crescent wrench. You really need a derailleur hanger alignment gauge like this one from Park Tool or this one from Campagnolo. Another advantage of a derailleur-hanger-alignment tool, besides its accuracy in getting the hanger lined up perfectly parallel to the plane of the bicycle is that it keeps the threads from deforming while you’re bending it back.
― Lennard

Dear Lennard,
I have a custom Ti bike with the welded-on seatpost bolt (not sure why they do that, external collar is much more practical). The nut part is stripped; the bolt(s — I tried several) just spin freely as I try tightening.

Are you aware of any way to fix a stripped seatpost nut like that? I can get a longer bolt and put an external nut on, but fear that will fall off on the middle of a long ride and I will have to walk, and also remember to bring spares as well as extra tools. Best would be to fix it properly I think, just not sure how. Of course sending back to builder to re-weld on a new nut is an option, albeit very expensive option. We have no Ti bike builders where I live so would have to send somewhere.
— Jonas

Dear Jonas,
Generally, that is a robust binder method, and it sometimes is preferable to a seatpost collar, if the seat tube is super stiff, which is an issue with steel frames with 1-3/8” seat tubes and 30mm-diameter seatposts; the collar simply can’t pull the stiff seat tube tightly around the seatpost.

Your options are:
1. Put in a longer bolt with a nut. As long as you use a locknut (one with a plastic insert in the threads, it should not unscrew. And it wouldn’t tend to loosen up, anyway, as it will be so tight.
2. Tap it out to the next bigger bolt size. The problem here is that, unless you find a very special bolt, the head of the bolt won’t recess into the pocket for it. You could file away the thin walls forming the bolt-head pocket…
3. Saw and file off the seat lug and use a seatpost collar.
4. Ship it to a framebuilder to weld on a new seat lug.
― Lennard

Dear Lennard,
Before I waste $60 on this cassette, I had a quick question. I am running a 52/36 chain ring upfront with a Di2 Ultegra RD-6870 rear derailleur. It doesn’t look to be a long cage. Can I run an 11/32 cassette in the back? Would I just need to adjust the b screw?
— Caleb

Dear Caleb,
Yes and yes, at least with some derailleur hangers. I have done exactly that on two of my own bikes. You will indeed need to tighten the b-screw.

And I have an RD-6870 GS (Ultegra Di2 long-cage rear derailleur) that I’m running with an 11-36 cassette. I had to turn the b-screw in most of the way. Works great. I ride that bike almost every day, and I wouldn’t do that if the shifting were at all problematic.
― Lennard

Dear Lennard,
I was watching a riding video recently and they were giving tips to beginning road cyclists on climbing. The video said that you should get in your “climbing gear” before you begin your ascent. Is this advice still valid given the advances in modern day drivetrains? I understand possibly getting in to the small ring but some interpret that as not shifting rear cogs under load while climbing. I ride on SRAM Red 11 mechanical and have never had an issue shifting while climbing seated or standing — I am sure electronic shifting systems are even better. I’ve always told beginners you want to be in the right gear and cadence regardless.

Dear Doug,
You are of course right that the rear shifting these days allows you to shift under considerable load. That said, you do reduce the stress on the system and the likelihood of a mis-shift by easing off a bit when shifting. And with front shifting to the inner chainring, easing off on the pedals is almost a must. Given that beginners don’t tend to do this, I think it is still good to tell them to ease off when shifting.

I have thought about this a lot recently, as I have an Ultegra Di2 setup that I’m running on full Synchro Shift (Shimano’s option S2), and one of the shifts requires me to significantly back off on pedal pressure. With full Synchro Shift, you only need to shift with the right shifter. When it reaches the pre-programmed points (which you can change via the eTube app), it shifts the front derailleur and shifts back two cogs in the opposite direction on the rear.

I can do any shift except one under high load with this set-up. All rear shifts are smooth, even under load, especially downshifts. When on the inner chainring and the fifth-smallest cog, it warns me on my Garmin: “Chainring shift next,” but it almost doesn’t need to. When I click the upshift button once more, it simultaneously shifts the chain up to the big chainring while shifting two cogs larger, to the seventh-smallest cog, and it does it so smoothly that I hardly notice it.

However, when the chain is on the big chainring and the second-largest cog, my Garmin again warns me: “Chainring shift next,” and for this shift, I appreciate the heads-up. If I click the downshift button once more, it simultaneously drops the chain to the inner chainring while dropping down two smaller cogs in the rear, to the fourth-smallest cog, and there is a lot of clunking going on while it’s doing it. Part of that is that I am running the setup I mentioned in the prior answer; I have big steps front and rear, as this is a gravel bike on which I’m running 50-34 front chainrings and an 11-36 rear cassette. I do that shift only on steep climbs, and I have to back way off on pedaling pressure when doing it, and still it is a hard clunk in the rear.
― Lennard

Feedback on silk tubulars

Dear Lennard,
I just read the article on silk tubulars by Lennard Zinn. I too raced in the late 70s on Clement Criterium Seta (250g) and Seta Extras (220g), on Fiamme Red Label and Ergal rims. And I clearly remember at 25 mph, they made a unique sound — I called it the sound of speed because when you heard it, you knew you were cooking along.

Just like Lennard, I miss those tires. They were truly amazing in the way they felt, handled, and accelerated. They were just stupid expensive at the time, and everyone was telling me I should be on Continental cotton tires. My last ride on the Seta Extras was quite notable. I was racing in the 1977 Carnegie Mellon Classic, put on by my local club, the Allegheny Cycling Association. On the first turn from the top headed for the downhill section charging hard when the rear tire had a sidewall failure. I had raspberries from my hip to my knee for a couple of weeks… but I still fondly remember many, many Thursday night crits at the Highland Park Zoo parking lot on those tires and wheels racing against the Chew brothers, Tom and Danny. Thanks for the memory jog!
— Lance

Dear Lance,
And thank you for the memory jog; I, too, remember Fiamme Red Labels and Ergals fondly.
― Lennard