[Closed] How can a front hub be 29er specific?

Was thinking about this the other day as I've a Hope Pro II hub waiting to be built into a wheel. I've got it because a spoke ripped out of the flange, which made me wonder if this part would have to be different/beefier if it was going to be used on a 29er. More leverage from longer spokes or something?

Does it have sticker on it saying "29er" .... ?

That is probably the only difference.

It doesn't look like it has thicker flanges, but it doesn't say "29er" on it either. Must be something else ❓

Does it cost more?

My new hubs are 650b compatible. The bloke in the shop reckoned they were the only set in Europe. Bit more expensive but worth it in the long run.

The only reason would seem to be that it matches the rear M629 hub, which is also "29er specific".

The only reason the M629 rear hub is "29er specific" would seem to be the "Micro ratchet mechanism freehub: Quicker engagement (11.25 degree) & faster acceleration".

Whether this is an improvment so to speak, or Shimano's way of admitting that the durability and pickupn of the old freehub might not have been good enough for larger cassettes and 29" mountainbike wheels is anyone's guess. 😉

Could it be LH flange offset?

Total guess here but I do remember one of DMRs earlier rear disc hubs if built up with a 26" rim and a 160mm rotor ran the risk of the calliper clashing with spokes as the flange was to far outboard.

Scale the same problem up a tad for a 29" rim and hey presto you need a slightly more inboard and/or smaller diameter disc side flange to ensure the spokes don't clip your calliper if run with a 160mm rotor.... Perhaps. Or just use bigger rotors.

[url= http://forums.mtbr.com/singlespeed/revolver-rear-hub-disc-brake-296047.html ]nope I didn't imagine it....[/url]

IN a word: marketing guff.

they use different grease to allow for different rotational speeds

Actually Julianwilson was closest [url= http://bikemagic.com/gear/shimano-introducers-29er-specific-hubs.html ]apparently it's due to higher torque on the freehubs[/url]

Might be more marketing than anything else...

^and higher torque via braking forces (larger diameter= more leverage) hub tries to stay still while rim is trying to turn?

Hardly "29er specific" though, is it? Still works quite happily on a 26/24/20/16/650b/whatever.

As the op asked about front wheel applications I would go with extra torque on the disc mounts and also extra material or strength on the flanges for lateral forces. I think it's time hope brought back the big un for twenty nine duties...

I think it's time hope brought back the big un for twenty nine duties..

That thing was a beast. It looked like a moped hub.

My new hubs are 650b compatible. The bloke in the shop reckoned they were the only set in Europe. Bit more expensive but worth it in the long run.

[img] [/img]

What a load of old TUT!

The extra torque generated by a 36t sprocket is enough to make that a big ask for a regular freehub, hence the new high-torque rated M629

I'm getting my bullshit bingo card out....... 🙂

Could it be to do with [s]marketing nonsense[/s] the flange angle? 29er spokes have further to go before they get to the rim, so their angle must be *slightly* different to that of 26er spokes.

Although then I suppose we need rim width specific hubs as well!

I'll stick my cotton cap on, sip some coffee out of a Look mum no hands expresso cup and have a think about that one.

I'd imagine that they're for use on the Continent, not here?

Shimano beefing up their freehubs is a good thing, calling them 29er specific (if that's the only change) does indeed sound like marketing tripe.

What a load of old TUT!

cookeaa [url= ]the hub/brake/spoke fix[/url] looks tricky, wouldn't fancy building that.

think yossarian was joking peter.

I hope so! 🙂

cynic-al - Member
IN a word: marketing guff.

You need a 650B hubset to keep up with the cool kids these days.

http://www.shedfire.com/2012/10/03/650b-hub-set/

I'll guess that's a paste error from the rear hub, with the freehub that was designed to handle higher torque when 29ers started getting geared lower and 36T cassettes came out.

'Specific' or 'optimised', I guess their English is still better than our Japanese? The Shimano trade book has a few phrases like that in it, or the keywords that Capreo or Zee was designed around, etc. It's just cultural influence.

Either that ... or it's those crazy all-controlling marketeers at it again.. : )

i've got a pair of these hubs.

they're cheap, run very nicely, and if they're only as good as shimano hubs of yore then they should last years.

even better if they've been sturdified a little.

if it's only the rear hub that's been sturdified, and the front hub has been made only so that fools like me can buy a matching pair* of hubs, then i think that's cool too.

(*i'm not a wheelbuilder, i have no idea what i'm about to talk about: do the bigger hub flanges mean that shorter spokes can be used? - is this an advantage? - does the matching front hub mean you can use the same length spokes on the front and rear wheel?)

'Specific' or 'optimised'

Tandems (which have to deal with a little more torque than a 29er) have tandem-specific hubs. These generally have higher flanges and more spoke holes to build stronger wheels. I don't think they have stronger freehubs, per se.

Damnit, will nobody sell me a 29er-specific saddle?!

Well this one has bugged me a bit.

I don't think there's much case for a "29er Specific" hub needing particularly different flange geometry (other than the aforementioned potential Caliper/spoke clearance issue), there shouldn't be any more direct stress on the flanges, in theory the bettor rolling characteristics and reduced angle of incidence at the outer circumference should mean fewer shock loads being transferred through the spokes right?

I suppose the idea that a larger diameter wheel should generate an increased moment from lateral loading at the hub, but then the genius of spoked wheels is that they are all about transferring loads and translating everything into tension, the primary loading on a hub flange is still tensile stress directly through the spokes regardless of how the loading is applied at the tyre... in theory at least.

I don't think torsion at the disc mount is an issue really the resisting force generated by the brake is still the same (Unless there's a 29er specific brake I'm unaware of) changing rotor diameter will have a greater effect, but considering most 26ers with most calipers could pull a stoppie without any failure using anything from a 160 - 230mm rotor I don't think a meager 40mm more radius on the wheel will particularly scare your disc mounts...

Torque applied to the freewheel is an interesting justification, it does imply the margin to failure on shimano's extant hubs was pretty low to start with, the link I posted previously was dated Feb 2009, about the time Shimano were starting to roll out 36T sprockets (in 12-36T, 9 speed format again as "29er specific") they are correct of course a slightly larger sprocket will increase torque on the freehub and they only went and gave us the tests input values:

[img] [/img]

Fag packet maths says the Freehub needs to withstand an additional 35.7Nm of torque with a 36t sprocket. To apply the same amount of torque using the old 32T sprocket our test mass would need to be a shade over 2 stone heavier...

So I would definately buy these hubs if you weigh in excess of 52 Stone, although I expect you've probably got enough issues getting out of your reinforced bed yet alone picking a pair of hubs for your 29er...