Is there a definitive reason why "tandem" specific hubs are as wide as they are, 145 to 160 usually? I'm looking to build a set of wheels and the limited amount of options at these widths is driving me crazy. We currently have a 160 and 145 spaced tandems and are having a new frame built and I'm comptemplating a switch to a narrower profile hub.
The reason I'm thinking this is a friend of ours and his wife have been riding a custom Davidson using a set of standard 130mm Mavic Ksyriums SLs now for almost 3 years with not a single problem. I'd guess their team weight at between 275 and 300lbs, they ride hard, lots of miles and even race occasionally. They run Campy 9speed.
I'm thinking of going to 135mm White Ind hubs for this build but would appreciate any and all comments, opinions and real world experience stories.
I specd a set of wheels today that came in under 1800g and cost less than $700. The build was:
Rear wheel:
White Ind 32h non disc with a Velocity Fusion rim and DT 14/15 spokes
Front wheel:
White Ind 28h with a Velocity Aerohead rim and a bit lighter DT spokes
KRhea
TandemGeek
02-14-08, 09:56 PM
In the early days before mountain bikes, tandems used single road bike spacing and single road bike components which often times meant wheel durability was the Achilles heel for many teams that weren't fly-weights. You'll note that Schwinn Paramount racing tandems even used higher rear wheel spoke counts (40 or 48) than what was fitted to the front.
Somewhere along the way, mountain bikes and 135mm rear spacing became available to tandem builders and as 5 speed gave way to 6, 7 and 8 the flange widths simply grew to 140mm, 145mm, and even 160mm in anticipation of 9 and 10 speed cassettes. These wider rear axles and hubs allowed for non-dished rear wheels which are, quite frankly, a heck of a lot stiffer and more reliable for most teams. Remember, production tandems are built to meet a very high standard for strength and durability since they must be suitable for teams of all sizes.
If your friends have been able to successfully run a Davidson with 130mm Mavic Ksyriums at their weight I would say they are the exception, and not the rule. I say this because a number of tandem teams jumped on the Ksyriums when they were first introduced and gave them rave reviews during the late 90's (search the Hobbes archives for Ksyrium). However, after a while the reliability fell off and most all of the folks who were running them quietly replaced them with more durable wheels... some still spaced to 132.5mm or 135mm because that's how they had their tandems built. The 132.5mm spacing is used to allow for 130mm or 135mm wheels. That said, we know of a few teams that run narrow spaced (132.5mm) tandems with both tandem-rated wheelsets and some non-tandem rated wheelsets that were intended for race day use that ended up pulling daily training ride duty. In most cases, while some of the non-tandem hubs (Campy Record, which are bomb proof) held up just fine, the spoke beds are where the weaknesses in the lighter weight rims manifested themselves, turning those one very nice rims into junk. However, they continue to run Chris King / Velocity Deep-V with 135mm spacing or similar types of wheels and put tons of very hard miles on their tandem.
So, I guess what I'm suggesting is, while wheel components have gotten better and will make for some durable wheels, I'd want to be sure I had a good reason for giving up the safety margin and added durability of a nearly dishless wheel for anything but a dedicated time-trial bike where I needed to use my $X,XXX ZIPP disc wheels for the US Nationals.
Also, as noted in another thread, lightweight wheels have their place; however, if you do all of your base miles riding and training on your racing wheels, then where is the benefit on race day?
Bottom Line: There are exceptions that prove the rule for just about everything. It's your tandem: build it the way you want it but do so with your eyes wide open. If you have wheel issues down the road, re-space the rear drop-outs, get an new rear wheel, and move on with another lesson learned in the book. If they hold up just fine, then good call.
dfcas
02-15-08, 07:22 AM
I have no answers,but I do have more questions concerning flange spacing.
I remember that White Industries 145 tandem and 135 mtb hub actually have the same flange spacing and use a spacer to locate the disc flange and get the over lock nut dimension to 145. Obviously,the axle is longer.
I think I remember that some other tandem hubs have single bike flange spacing,but I'm not sure about this.
So,maybe the real question should be flange spacing instead of OLN?
TandemGeek
02-15-08, 07:37 AM
I remember that White Industries 145 tandem and 135 mtb hub actually have the same flange spacing and use a spacer to locate the disc flange and get the over lock nut dimension to 145. Obviously,the axle is longer.
Daisy Non-disc White Ind. Tandem Rear Hub: 55.5 or 58mm flange width (54 or 60mm flange diameter) depending on which White data you read
MI6 Disc White Ind. MTB/Tandem Hub: 53.5 or 58mm flange width (60mm flange diameter) depending on which White data you read
MI5 Non-disc White Ind. MTB Rear Hub: 56mm flange width (55mm flange diameter)
So,maybe the real question should be flange spacing instead of OLN?
Yes and no. While the flange spacing is the same, the wider rear axle allows the wheel to be built with far less dishing, which is where the increased lateral stiffness and durability come from. Therefore, when specing rear spacing and hubs, all of the variables need to be considered.
......In most cases, while some of the non-tandem hubs (Campy Record, which are bomb proof) held up just fine, the spoke beds are where the weaknesses in the lighter weight rims manifested themselves, turning those one very nice rims into junk. ....
I assume you are saying the "spoke bed" is on the rim and not the hub flange.
TandemGeek
02-15-08, 08:51 AM
I assume you are saying the "spoke bed" is on the rim and not the hub flange.
Yes, that's the lexicon that I'm familiar with or have at least always used.... right or wrong. The hub's spoke holes are, well, the hub's spoke holes.
masiman
02-15-08, 09:48 AM
Yes, that's the lexicon that I'm familiar with or have at least always used.... right or wrong. The hub's spoke holes are, well, the hub's spoke holes.
Thanks. I don't spend alot to time in the wheel technology arena. I just wanted to be certain that it was the rims and not the flanges where the issues were observed. More specifically, with lighter weight rims.
I do know that the flanges do acquire a wear imprint from the spokes, especially in the MTB arena. I think I have read of a few flange failures but not at rates that make the flanges a major cause of hub replacement.
TandemGeek
02-15-08, 10:53 AM
I think I have read of a few flange failures but not at rates that make the flanges a major cause of hub replacement.
They are indeed rare and most of the flange failures I've seen or heard about on tandems occured on hubs that had material removed from between the spokes to reduce their weight, e.g., White Ind. Rocket front hubs and the drilled ones used on some of the earlier Rolf's front hubs. A few others usually happened when someone went with radial lacing, or where the wheel was simply over-tensioned to an absurd level and, shockingly, the flange broke before a spoke was pulled from the rim's spoke bed.
KRhea
02-15-08, 12:26 PM
Thanks for all the reponses, much appreciated. I would think the overall strength/durability of a narrower spaced wheel would be greatly dependent on the quality of build as well as the simple fact of more/less dish. As I'm sure we're all well aware, every builder does not build the same way, with the same attention to spoke tension, with the same amount of experience, attention to detail etc etc.
If this is incorrect and excessive dish isthe harbinger of all things bad with narrower tandem hubs please let me know.
KRhea
dfcas
02-15-08, 12:56 PM
"M16 Disc White Ind. MTB/Tandem Hub: 60mm flange width"
I went back and looked at my notes from when I was considering building a set of disc brake wheels using the WI m-16 hubs.
The 135 mtb rear is offset C-L 35mm and C-R 18.5mm,for a flange width of 53.5mm.
The tandem version at 145 is offset C-L 30mm and C-R 23.5mm,for the same flange width of 53.5, so the bracing angles are better on the 145 version.
Note that the tandem disc hub is not listed in the specs on the website.
TandemGeek
02-15-08, 01:55 PM
I would think the overall strength/durability of a narrower spaced wheel would be greatly dependent on the quality of build as well as the simple fact of more/less dish.
Unless I specify otherwise, all things are considered equal when comparing the different wheel specs.
While there is such a thing as overkill, e.g., 160mm rear spacing or 48h wheelsets for teams that weigh under 300#, I believe it's fair to say that as the rear wheel spacing narrows and rear wheels on tandems get dished, durability and reliability are diminished. As to at what point a given team of a given weight will experience an adverse result, that's hard to say. I've seen lightweight teams with stokers that are bounchers who punish wheels and captains who never miss a pot hole and don't own a spoke wrench. Conversely, there are very large teams who ride clean and who keep their equipment in top flight condition that seem to never have wheel problems.
So, without knowing which camp you might fall in or a number of other things that might influence how hard you and your stoker are on wheels, there's no way to even venture a guess at how well even the best-built 130mm Ksyrium (or similar) wheelset might hold up and for how long. As for your friends, a sampling of one does not itself make for a trend. However, I suspect their Ksyriums have held up better because their tandem was built with 130mm spacing vs. the ones where folks modified the Ksyrium axles to work on drop-outs with wider spacing. Again, I've seen folks running all kinds of wheelsets that weren't designed for tandems: they just don't last all that long or inspire confidence for 60+ mph mountain descents.
Final shot: Ignore the fact that your putting the wheels on a tandem and just evaluate wheels based on your total team and bike weight. If a set of wheels are good for 350# single bike-riding Clydesdale, they're probably OK for a 330# tandem team.
TandemGeek
02-15-08, 01:57 PM
Note that the tandem disc hub is not listed in the specs on the website.
True, but the MI6 disc hub is essentially the MI6 tandem disc hub (and perhaps the Daisy hub as well). White simply uses a wider axle configuration with less dish, they don't machine away as much material on the disc adapter, and the use a steel cassette carrier (or Ti, if you specify it that way) instead of the aluminum one used on the 135mm MTB version.
Also, and it's hard to tell with their choice of fonts, but the proper nomenclature for the mountain hubs are the 'MI5' (emm eye five) and 'MI6' (emm eye six)... not a clue what that means since they've also used names like Rocket, Speed Racer, Racer-X, and more recently 'Daisy' for tandem hubs.
TandemGeek
02-16-08, 11:30 AM
For future reference, and until they kill it off, here are links to the somewhat hidden White Ind. tech pages:
HUB SPECS (http://www.whiteind.com/Tech_Info/wheel-build-dimensions.htm)
These don't seem to jive with the current web site's specs, so it's probably best to check with your dealer or White on flange spacing / hub diameter to be sure what they are currently offering.