bobbotron

I was talking to a friend the other day about touring bikes, and I was saying that I thought a lot of touring bikes used mountain bike hubs as opposed to road hubs as they're more durable. However, now that I think about it, does that make sense? Can you get mountain hubs that fit into the rear chain/seat stays of a touring bike? (I'm new to this.)

MichaelW

Yes. Most modern loaded touring bikes are specced for 135mm to use MTB hubs. A couple have an inbetweeny 133.5 OLD to accept either. Only light touring bikes have the road standard of 130mm.

MrPolak

Mountain rear hubs are 135mm and road hubs, the newer ones, 130mm. The good news is that a pure touring frame which takes 700c wheels "should" have wider rear drop out spacing such as 132.5mm (as in the Nashbar touring frame). If not, you can spread the rear seat stays on a steel frame to accept the wider mountain hubs.

I'm not sure about the forks, but I think they have the same width.

NoReg

135 is standard on touring bikes. My recent touring frame was a perfect fit for 135. Some custom bikes use 145 spacing for tandem hubs, there is a 165 hub also, and maybe someone will use that some day. The advantage to wider hubs is wider lateral spoke staying base. The strength of the support varies as to the cosine of the angle at the hub. With the 145 hubs, however, these tandem hubs do not necesarilly have wider spacing since they carry drum brakes on the non-freewheel side. So one shouldn't assume every wider hub is an improvement in spoke angle or symetry.

bwgride

Do you have a forumla for calculating relative strength/weakness of spokes from drive to non-drive side for rear hubs?

NoReg

I don't, that is just a standard rigging formula. Like if you had a flagpole and you were using some wire rope to hold it up in a wind the effect of a 60 degree wire vs a 45 degree wire would be .5 to .7 (their Cos). At a zero angle, the line parallel to the pole, you get 0 and at 90 degrees to the top you get 1, full strength. Same deal with diamond wires on spars in boats.

These numbers do indicate the effect to the wider hubs is pretty minimal. I did a quick scale cad drawing using the inside diameter of my Ma2 26" rim, and using the full width of the hubs as the flange width for absence of the real numbers. There was 1.1 degree of difference in the angle, between a 145 and 135 and it added about 6.7%. Between a 135 and a 120 there was 11.6 %. Again, these figures are based on full width flanges, but they are proportionally correct, I hope. In the real world the makers may not proportion the flanges proportionally to the width.

The rim is the same as a flagpole in the example above except it is held firmly in a third dimesion, rather than being a strut going to the ground, the spokes don't know the difference. Spokes operate in three dimensions also, but for the purposes of the hub width I don't think it is relevant.

I am not an engineer so with luck someone can jump in and bash this stuff about a little. Though I did once model it for a wire on a boat using a quality spring scale, a weight and some cord and the results modelled very closely to the engineer's calcs. See, you can save money on college, though nobody hires you (with good reason :0)).

amaferanga

I believe that another significant reason why most touring bikes have mtb hubs is that they're better sealed than road hubs, which matters when you're on the road for a long time.

I'm of the opinion that dishing of a rear wheel has more of an influence on wheel strength than hub width. Stands to reason that you want equal "stretch" in the spokes on either side of the hub which is best achieved with equal tensioning of spokes either side. One of the reasons for running a Rohloff hub gear.

But then I'm no engineer either so.......

bobbotron

Right! I was thinking about hub sealing when I made this post. I am thinking of getting a front mountain hub on my road bike's wheel for this reason. I ride it in all kinds of weather, I degreased the front hub once already from wet riding.

ncscott

I'm confused... Why would a manufacturer have a better technology and choose not to use it just because its intended for a road bike? It would seem that if a better seal is available, then Shimano or who ever else would would price similar models of hubs with similar seals. But I'm not a designer or engineer.
It would seem that since most mt bike hubs are now made disk compatable that any advantage in dish would be offset by the disk mount. I realize that getting a non-disk mount hub would eleminate the problem...
Scott

radical_edward

Because road kit is about weight and nothing else. Half a gram of rubber seal is half a gram. And as the market is assumed to want gear that is identical to what the pros run so even low end road gear is built with little sealing. Because everybody repacks their hubs before a race, right?

On the other hand Shimano still make high end mountain bike hubs without disk mounts, as v-brakes are still a weight saving option for the XC rider. The Deore hub is pretty much identical to the high end Shimano hubs (same seals, bearing races not as highly polished) but is dirt cheap.

If you are due for a new front hub and want to build a bulletproof set of wheels then you can't go wrong with a mountain hub on the front. It would be fantastic if Shimano made a 130mm rear at deore level with better seals. After all, they reintroduced cantilever brakes due to increased demand for Cyclocross and Touring bikes.

Alex L

Probably additional sealing creates additional friction inside the hub as well. This is not reasonable for road cycling.

bandregg

I ride Chris King hubs on my touring bike. You can get the back in either 130 or 135. The front is standard. They are definitely up to the rigors of touring.

grolby

Hub width makes for a stronger wheel because the resulting wheel has less dish.