Stormy Archer

I have 2 pairs of 26mm clamp drop bars. They both have grooves for cables. One is 7000 series aluminum and weighs about 200g, the other is 6000 or 2000 and weighs more like 300g.

I know that 7000 series aluminum is stronger and stiffer, hence they are able to make it lighter. But with a tube, will the thinner wall in the metal cause the bars to be more compliant than a thicker, heavier bar?

I'm looking for more compliance, if anyone is wondering.

sweeks

How much flexibility is good in a handlebar? Seems like thicker tape or some kind of padding would give more comfort, if that's the objective.

hsuBM

I don’t know that many alloy bar brands State their wall thickness, so you’ll just be guessing by weight and trusting their claim of 1) that weight and 2) the specific alloy.

In the end it’d be a trial thing for you to go through ten, twenty, fifty bars before you find your Goldilocks bar for one particular frame.

Enjoy that rabbithole.

you haven’t stated your drive toward flexy bars, I’m assuming that it’s for either a sort of suspension beyond wrapping an obnoxious amount of foam on the bars or as a short term energy savings account which you cash out when the cranks are vertical.

I’m there in the latter priority with frames, just saving to have Waterford build me three identical frames, each with different wall thicknesses in the main triangle.

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regarding comfort, the biggest contributors I’ve found for that are where your contact points are (fit), your core strength (your body’s ability to keep weight off of your hands without you having to think about it), and tires.

HillRider

The amount of comfort offered by even the most flexible bars is minor and probably unnoticable to the rider. Padded bar tape and good riding gloves are far more effective. The ultimate approach is, of course, a suspension fork.

Crankycrank

Seems to me the only way to answer the question is to mount the bars and test them out.

Litespud

not sure I’d be looking for compliance (ie flex) in an Al handlebar. Sounds like just asking for fatiguing and eventual failure. If you want to reduce road buzz, look at thicker tape or better gloves. If you want to reduce bigger hits, look for some shock-absorbing strategy that doesn’t depend on the flexion of a thin-walled Al tube, the failure of which could result in a life-changing accident. I use lightish Al bars (lightest was a Cinelli - claimed “sub-200” but ~230g actual), but I’m not a power beast who torques the bars to any extent. Even then, I replace them preemptively every 10 years or so. You really don’t want your Al bars to flex. If you’re anyway a Clyde or put out significant power, the handlebar isn’t where I’d be looking to save weight

70sSanO

I would think compliance, “measurable” flex, is the last thing any bar manufacturer would want to incorporate into a component that is used to guide a bicycle over various types of terrain.

if you want more compliance, look into a shock absorbing stem like a Redshift ShockStop.

John

Moisture

You'd have to turn to some extra passing and cushioning as.mentioned above.

79pmooney

From my "Reyerson Stock LIst", a reference book of metal shapes, sizes and properties' 7075 T6 - 70,000psi yield, 10,400,000 modulus. 6061 T6 - 40,000 yield, 10,000,000 modulus. 7075 is listed as 3% heavier than 6061.

So, the 7075 is 75% stronger and 4% stiffer. As far as rider feel goes, strength only matter when you tweak your handlebars so hard they either bend or break. Up to htat point, breaking or yeild strength doesn't matter at all. The modulus of elasticity does, That is the material "spring constant". But a 4% difference? You won't feel that. If the diameter of the handlebars is the same, the only difference you will feel is from wall thickness. The densities are nearly the same but taking that into account - a 200g 7075 will have wall thickness 200/300 X 1/1.03 = 65% of the 6061 wall thickness and 55% more bend (or "give") for a given road bump.

But - outside diameter counts for a lot! Often stronger materials mean the makers boost the diameter to offset the stiffness lost from less material. The 7075 bars could be made with 22% larger diameter, 19% less wall thickness for the same weight, be 100 gm lighter and have the same stiffness.

So if the lighter bars are an exact copy, same outside diameter, they will be a lot less stiff but if the makers boosted the outside dimensions, stiffness rises fast. Calipers will be your friend here. Our speculation won't add up to much. Tell me the outside diameters beyond the center sleeve of both bars and I can make a reasonable guess at the relative stiffnesses. (Be aware that light, high strength, large diameter tubes break differently than smaller diameter tubes of lesser alloys. The small diameter tubes tend to bend first. The larger diameter tubes resist bending and break. (Years ago I was riding a tired pair of GB bars (made circa 1970). Dropped my front wheel into a deep late winter pothole. Wheel was OK so I just kept riding. 8 miles later did a routine glance down. What! My bar had a 30 degree kink down at the outer edge of the reinforcing butt! The blessing of very mediocre alloy, Bent like a soft noodle rather than breaking.) With the new stuff. replace before handlebars break!

WizardOfBoz

Yes, the OD matters, but if the ODs are set by the clamp diameter (that is, they're nearly the same) with a mass ratio is 300:200, the three or four percent difference in modulus won't matter that much. The 200g bar will be more compliant. More importantly, which is more comfortable for you? Choose that one.

Theory's great, but it doesn' overcome overwhelming design differences.

CliffordK

Specialized made some aluminum bars with Zertz. They pop up on E-Bay from time to time. I have a pair, although I'm not certain I can really feel the difference between them and solid aluminum bars.

https://www.ebay.com/itm/Specialized...e/402330131871
https://www.ebay.com/itm/SPECIALIZED...R/274536605153

It looks like one of those bars may also have gel pads. They are comfortable as long as they don't leak.

What is your ultimate riding goal? I ride on the "tops" of the bars a lot. And, I find the flat top bars (aero) much more comfortable than the round top bars.

There are a few aluminum aero bars, and most of the newer carbon fiber bars have an aero profile.

Darth Lefty 

Short version: yes they are, and yes compliance is suspension, and yes it's good.

In researching my little thread over in the commuting forum about suspension forks, I ran across the BQ tests on rumble strips. Setting the tire stuff aside, they found that a 531 SL fork, and a Rockshox Ruby (second gen with elastomers and pretty poorly regarded), had about the same energy loss, and both were way better than a heavy duty, likely hi-ten Trek Multitrack fork... even on the smooth pavement, not just the rumble strips. They were also noticeably more comfortable to ride.

You can extend that way of thinking to the entire frame and cockpit. Indeed things like Zertz and Isospeed are doing just that.

grizzly59

Aluminum is not supposed to flex.

CliffordK

Is that why so many soda and beer cans are made out of aluminum?

Many of the early Aluminum bicycle frames had complaints about too much flex, eventually being replaced with stiffer alloys thicker tubes, and different tube profiles. Which all resulted in complaints of not enough flex.

Extruding and mandrel forming of handlebars may aid with ductility, as well as final heat treatment for strength.

A little flex may well be designed into the part. Unfortunately, Aluminum may also experience fatigue limits (something one normally doesn't get with the soda can unless trying to tear it).

Darth Lefty 

You had better tell all the engineers, they will be alarmed to hear this and stop making stuff of aluminum immediately

blamester

If you want compliance go carbon.

icemilkcoffee 

That's the truth. Carbon bars are noticeably smoother riding. Whereas I cannot tell the difference between a regular Al bar and a thin-wall 6061/7075 Al bar.

noglider 

Who says?