Straight pull versus flanged hubs

Straight pull versus flanged hubs

People had a strong response to that frame business post! When we started this "people are bored and in need of a cycling fix so we'll just blog every day" thing, we didn't have any plan for it. We were sure we didn't want it to be like the (major online cycling retailer redacted) emails I get every morning with 30% off Castelli! Buy Now Now NOW!!! (I assume many of you get them, too), but beyond just sort of throwing something entertaining and maybe informative/thought provoking/whatever, no, there was no grand plan. But the response has been astonishing. Our blog traffic is every day now like it's only been when we've done wind tunnel tests or other big news stuff in the past, and mostly the biggest responses have been the "our history" kind of posts. Which made us realize that we're really poorly calibrated to that aspect of our audience. Some of you have been here since the start, while more and more don't know that we've been internet jackasses for a decade now. So, thanks for reading, and we hope that this is all over and we can go back to normal life and blogging schedule soon. We've done a year's worth of posts since 3/17 and, well, it's fun but it's not that easy. 

I built my first wheel because of straight pull hubs. The year was 2007, it was my first year of racing, and a fellow racer had done me the kind service of putting his front wheel into my derailleur and causing all sorts of mess in my rear wheel. The Easton/Velomax Circuit wheels (h/t to the internet bc I couldn't remember the model) that were my first "race wheels" had straight pull spokes with regular nipples at the rim, but the spokes were screwed into the hub as you can maybe see in the picture below. 

Let me tell you, those spokes weren't coming out of that hub for love or money. No amount of heat or force or cajoling could undo the thread lock and those wheels were toast after about 2 months of use. And I thought it was just outrageously stupid that a simple broken spoke could wreck a wheel. So I took the rim and laced it with the Powertap hub I'd just bought and it was a hideously built wheel that I keep making better and better until it was actually something usable. That still didn't make me anything like an accomplished wheel builder, leaving room in the universe for the Larry wheels episode. The funniest part of the whole thing is that the guy whose front wheel smacked my rear wheel wound up doing a bunch of wheel builds for us, for a long time, and he was fantastic. Anyhoo...

I'm using DT350s for the illustration here, simply because I knew QBP has good images of everything I want to show, and DT350s are representative of the general differences between straight pull and flanged hubs. 

The top two hubs (the disc ones) show stated weights of 137g (straight pull) and 136g (flanged). The bottom two show stated weights of 110g (straight pull) and 149g (flanged). I know the flanged weights are accurate because I've weighed them recently while having discussions about this topic with people. The percent increase in the rim brake hubs is a lot, admittedly, and I don't know why their rim brake hub is heavier than their disc hubs. So when we talk about weight, sometimes a straight pull hub can be lighter. Not all the time. 

Do you see the lateral space between the holes on the disc brake straight pull hub? Those are wider apart than a flange. That means the inboard spokes get pushed a hair farther in. You can't just push the outboard holes farther out. So the inboard spokes are going to be a little bit farther in, which is a little not better than if they were farther out. When you interlace the spokes as they cross, you average the bracing angle of the crossed spokes - their effective bracing angle becomes the angle from the cross. As far as I can tell, that's the only reason to interlace spokes. I built a pair of wheels without interlacing them just to see what would happen and what happened is I rode a perfectly good set of wheels for a year. So there's that small niggle about the geometry. 

Building straight pull spoked wheels with round spokes is something I've done and it stinks. It just takes time because the spokes want to spin and since I've generally become smart enough to charge for time, the smarter equation is to spend that money on bladed spokes and save the extra time charge and then you get bladed spokes. 

The most prominent argument I hear for straight pull hubs and spokes is that there is no bend in the spoke to fatigue and break. While this is true, it's not generally relevant for us. From the adamancy of the argument, you'd think j-bend spokes were snapping off left and right, but they certainly aren't on wheels we build. I'm all for making things easier to do correctly, and making things more idiot proof, but the process of a good wheel build is straightforward enough that this doesn't have functional applicability from our narrow perspective. If you plan to have a set of wheels built poorly, perhaps straight pulls are better? And straight pulls don't have a perfect record either - a bunch of local riders have had straight pull wheels come with their new (major manufacturer's name redacted) disc bikes and we wound up replacing a PILE of those spokes that broke at the nail head. 

We've seen flange failures and we've seen whatever you call the part that would be the flange on a straight pull hub failures. 

You would have to have great evidence to convince me that the reason straight pulls came along in the first place was not aesthetics and an "exclusive" look for factory wheels. And for someone who bangs the drum for color and stuff that looks cool all day every day, I'd be a hypocrite not to credit that at all. Cool looking stuff is cool, so long as it doesn't hamper functionality. 

A naturally big part of our preference for flanged hubs (and really this isn't us banging our shoe on the table and insisting that straight pull hubs are dumb) is simply that our favorite hubs to build with are so prevalently only available in flanged models. And why that is is a great question that I've never really gotten to actually considering until now. 

I sort of wish there was more to this, but it's pretty straightforward. There are some small differences between the two types of hubs and spokes, but they don't amount to a whole lot. There are many more flanged hubs available to us to build your wheels with, so naturally we'll have more of them on offer. But we aren't in the business of saying no as a habit. There's some stuff out there that we think is junk and we won't sell it, but if you want a set of wheels with DT or Carbon-Ti straight pull hubs, we'll gladly build them. 

Have a nice weekend, stay sane, we'll get through this. 

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Straight pulls can sometimes have the spokes a bit closer together than J bend but they are usually very similar for both types.

Other advantages of straight pull include:

It is far easier to lace a wheel for a beginner. (The holes direct the spokes in the right direction. ‘All’ you have to do is thread them through the holes having lined up the logo with the valve. )

Another great advantage of a straight pull spoke is that, on a well designed hub and rim, you can fix a broken spoke with the wheel still on the bike as long as the nipple has not fired into the rim. There is no requirement to take the cassette, disc or tyre off.

Having just replaced a broken spoke this is a real advantage. Its loads cleaner and quicker and even if you do take the wheel off the bike to put in the truing stand you can leave the cassette, disc and tyre on.


“Easton/Velomax Circuit wheels”

Weren’t these the wheels that came with an owners manual that actually said to use a butane lighter to heat up the spokes for removal from the hub? I seem to recall reading something like that years ago from some company that was harping on the evils of the j-bend spoke. Any bike product that requires a Zippo for repair is an automatic turnoff.


Tom – Straight pull or flanged?

David – Hadn’t heard that but it makes some sense. It’s not like we’re going to abandon the convention, and without actually having the ability to measure it, I’d say it’s the exceptional event when a spoke in our wheels goes slack (we look for a minimum of 60kgf pre-tire install, which is pretty high). Good info, thanks.

Jim – This is the thing, and boy how well do I know that the blade cuts both ways, but reputations don’t build wheels. One of the stressful things about this gig is that there are real consequences if you build a stinker, and that happened with the original build. Spokes went slack and what happened is what happens. It wasn’t the hub type that did that.

I just looked because I honestly couldn’t answer the question for myself without looking, but we do trailing heads out on both sides, but I don’t think there’s a hill of beans worth of difference in it. If nothing else, both spokes in a cross meet at the cross.


I have a HED Belgium DT240 wheelset from a local wheel builder with a good reputation. It kept breaking spokes on the non-drive side right where the spoke butt diameter increased at the hub end, which happened to be right where they bent in (and apparently flexed) over the edge of the flange. The trailing spokes were head-in, so they bent at the flange. I bought a backup wheel from an online builder (before I knew of November), same rim, and a DT350 straight pull hub. It’s been fine, no issues at all, I specifically chose the straight-pull to avoid that bend in the spokes. Then last year I rebuilt the original wheel myself, lacing it with the trailing spokes head-out to avoid them bending over the flange. We will see. I have about 3500 miles on this wheel so far. Probably 5,000 on the straight-pull wheel. Lots of variables in the wheel building craft!

Jim Norman

You mention that the only reason to interlace the spokes at the cross is to average out the bracing angle. One other reason is that the interlaced spokes support each other and smooth out some of the tension variations as the wheel is ridden. This can make it (slightly) less likely for the tension to drop to zero, which is probably the primary reason that spokes fatigue.

David Hunter

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