You are hereForums / By Discipline / Mountain (off road) / MTB Gear / Handlebars and Stems - Help!!
Handlebars and Stems - Help!!
I have been looking at this handlebar http://www.jensonusa.com/store/product/HB402A00-...
It would be going on to an Anthem X 29er but it is a 25.4mm and is a 2009 model. It looks to me like all the bars these days are 31.8mm. Does this make a difference and should I avoid this bar. Clearly I am very clueless in this area so any expert help is appreciated.
Cheers
Ian
[Mod. moved to MTB gear]
- Login to post comments
- Bookmark & share
Tags
Keep away! wrong diameter. you have to have a 31.8mm unless you get a shim to bulk it out to size but its not worth it in my opinion.
Went from 25.4 to 31.8 in 2009 on the dually and the improvement in the feeling of sure-footedness and being in control on the front was massive.
just looked at the bars you may have well not bought the bike too be putting them bars on as you will be sitting up higher , you need less rise than that something in between what is on it & what you are looking at , I have the fsa K force carbon on my 29er & that has only a 18mm rise , I took the flatbar off mine too but didn't go too extreme & don't look at bar length as all bars can be cut back.
says wouldn't fit the 31.8 but on a stem that does fit it would be no problem @Hawkeye the difference must have been physiological because flex on either would be very similar and impossible to pick up riding trails the 31.8 was to make thinner walls with the same strength to save weight not make stronger bars - same wall thickness would be stronger. Check out bending and twisting moments if you're sceptical, and yes I am an engineer.
Like you I found that Jenson is unloading the 25.4 monkey lite's about $100 cheaper than I could find the 31.8mm models, I assume because they are slow moving lines now. Interestingly in carbon, the smaller diameter is lighter than the larger diameter. I assume this is because there is a minimum wall thickness they cannot go below whilst maintaining enough clamping strength
I have a brand new 25.4mm 110mm Ritchey Mountain Pro Stem still in its box if you're interested, from their website:
"This Ritchey stem has a 4 bolt faceplate to better distribute loads.
Threadless
Black
Alluminum
Handlebar clamp: 25.4mm
Steerer clamp: 1-1/8-inch
6 degree rise
Length: 110mm
145 grams"
let me know if you want to do something about it, it's in canberra and I'm about to head overseas on Tuesday for 5 weeks
@harry: Given that jump to 31.8 from 25.4 represents:
* a 56.7% increase in cross-sectional area of the tube at the clamp, and
* a 25.7% increase in tube circumference on which the stem clamp can act....
I'd be a bit surprised if that resulted in *no* detectable difference in stiffness. And note that I said stiffness, not strength.
Possibly a change in the alloy from 2024 T-something to 6061 T6 might have contributed to the sensation, but to claim that the difference in stiffness is only psychological (which I'm guessing is what you really meant) I find a bit surprising.
The only thing I changed was bar and stem, the rest of the bike was unchanged so it was effectively a back-to-back test over a trail I know well. The main reason I did it was to bring that part of the spec current, the extent of the improvement in directness I noticed was a pleasant surprise.