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Non-replaceable derailleur hangers on pro bikes

http://www.cyclingnews.com/photos/2...roubaix_sl2_09/Boonen_Roubaix_SL2_PR_dropout2
"Team bikes also use one-piece dropouts with non-replaceable derailleur hangers for snappier shift performance.
Photo ©: James Huang/Cyclingnews.com"

Looking at pro kit for the Classics.. I noticed a lot of non-replaceable derailler hanger setups.

1. How much difference does this configuration actually make to shifting?
You'd think it would be substantial but then again, these guys could probably afford to bin a few bikes during the Classics anyway..

2. Are the general public ever likely to see a non-replaceable config option?

cheers!
hip
 
A busted non replaceable hanger means a useless frame! Unless the dropout is made from steel or titanium then it is a risky thing unless you have a bike sponsor for your Sunday rides. I bet the hangers on these bike are carbon or aluminum. Soft aluminum replaceable hangers are designed to break or bend in a crash in order to protect the frame. This is a good idea for a carbon frame. I can not imagine that the difference is shifting performance is noticeable, if this was an issue I think that this would have been addressed years ago. Perhaps it is a function of the new dura-ace or campy 11 speed groups being very sensitive? Also, if the aluminum is too flexible then replace it with a titanium hanger that would be super stiff. Non-replaceable seems like nonsense and a waste of a frame in the case of a simple accident.

I would even surmise that this could be a marketing thing. Tell everyone that pros are using non replaceable hangers and then people will think that they need them too. When the bike crashes and the frame is wrecked then the rider will have to buy a new frame...good for sales. OK this is very very unlikely, even for the marketing driven bike industry.
 
I understand why MY bikes have replaceable hangers and I wish to keep them that way. I want to know though if there's REALLY a difference in shifting performance. I just don't see how there could be enough flex in that tiny hanger to make a noticeable difference.

I wonder if it's just because the bikes are one-offs, the companies know they're not going to be used more than a season (or even race) so they just don't bother with the replaceable hangers?

hmm...
hippy
 
Mar 19, 2009
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Maybe they want solid hangers on the bikes because a solid hanger is always stiffer than a replaceable one, there's just no way 2 pieces bolted together are as strong as one solid piece, or two pieces welded together. I'm surprised it took them this long to figure that out. Trends always run in circles.


Take into account that pros use their equipment at extremes. While the average rider may not notice any flex in any hanger, some pros would. Does this really make a difference in shifting though? I don't think we'll ever know a definite answer, because in the real world there's just so many variables. If you think it helps..... then it helps.

Pros are always looking for an edge though... however small. What parts have they not stiffened on a bike? There's nothing left.

I ride steel frames. If a hanger ever broke..... I have the frame builder replace the hanger for about $100 with some touch up paint. Mostly though, unless something really goes wrong to break a steel hanger, it just bends, and you bend it back.
 
The two pieces are not only bolted together they are held tight by the clamp pressure from the quick release. It is utter nonsense to say that a replaceable hanger is not as stiff as a one piece unit made from the same material (this is not a shot at you lostintime). The force on the hanger from the derailleur is very small, even under the most demanding shifts. This all sounds more like marketing or superstition than a rational explanation from the frame makers. There is so much more give in the shifting system (cables, shifters, derailleur). Grab the derailleur and flex it harder that any shift ever could and you will see that there is no flex in the hanger even if it is made from aluminium.
 
Mar 4, 2009
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You are forgetting a few key points here. The flex in the hanger generally comes from the area *below* the dropout itself so QR clamp pressure doesn't help. As compared to a one-piece non-replaceable unit, the replaceable hanger generally is half as thick in this area and thus is quite prone to flex depending on the design. Trek have continued to stick with a one-piece unit on the Madone largely for this reason.

Moreover, oftentimes the hanger is NOT made from the same material. Sure, it might be aluminum on an aluminum dropout but you're assuming the hanger is made of the same *quality* of material. Too often they're just some cast bit, not forged, and thus are prone to flex and fracture. Wheels Manufacturing have actually done a very good job of making aftermarket replacements for many frames using a much higher quality material (machined 7075 if I remember correctly) that generally holds up better than stock in many cases.

And as someone already mentioned, we also all have to remember that we're talking about pros' bike. These guys ride way more - and way harder - than most of us could ever dream. So while we may not notice the difference with some of the changes they request, that doesn't mean those changes are just for show.

Also remember that manufacturers aren't exactly boasting about making these things for the riders. Think about the message that would send to consumers. If anything, they'd probably prefer that we didn't notice.
 
James,

Point taken that all the flex would be below the QR point. If the flex extended above then the force would be huge and would also flex the axle! However even the cheapest 6000 series aluminum dropout is usually around 8mm thick and 30mm long. I would like to see it flex under the force generated by the derailleur actuating. There is so much built in play in the top pulley that any flex would be negated by this. The chain does not add much to the load since there is little tension below the freewheel even under the heaviest pedal load. In terms of real world practicality a softer dropout is better because in a crash it will bend or break without damaging the frame. In race world it would be better if it did not break or bend so that the rider could be on his or her way without a lengthy bike change. But the pros have a second bike waiting if the frame is damaged and thus in these terms it has merit but not in terms of flex.
 

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