qspencer

We use our tandems for riding with our kids. I want to set my wife up with a better tandem to pilot, but I'm trying to keep costs down because I don't know how many more years we can keep the kids riding with us. Right now she's piloting an ill-fitting and very heavy old Raleigh. She's just a little too short to fit a Cannondale M/S well. I've been considering Waltly in China, who build custom Ti frames (as well as OEM frames for other brands, I understand). Based on early consultation I think I can get frame and fork built and shipped to the US for a little over $2000 (that could change depending on customizations). With budget-friendly components (probably SRAM Apex, plus saddles and pedals that we already have) I hope to keep the cost of the whole bike close to $3000. If we use it a lot, we can upgrade some things later.

I'm considering Boost hubs front and rear, which will be possible if I get the Ti fork custom made with the frame. Boost seems to be here to stay for mountain bikes and I think makes a lot of sense for tandems. If I understand the 12mm through axle dropouts correctly, the 148x12 rear hub would be equivalent to a 141 mm QR hub. The Boost front axle adds an extra 10mm to 110x15mm. It seems like a great idea for tandems, especially with disc brakes. I assume that this should make budget-friendly Boost hubs and wheels based on them available for the forseeable future.

I know the dimensions for the front end pretty well, but I need to determine the stoker compartment length. My daughter (age 13) is 5' 6" (168 cm) and still growing, and my son will eventually be even taller (and neither will have the strength and bike-handling skills to pilot the bike for a few years yet). I've looked at rear top tube measurements of several tandems on the market and it seems the longest I've seen is around 72 cm, including most sizes of Cannondale. I'm curious if anyone here knows what is the tallest stoker that is likely to fit on a tandem of that length?

twocicle

Stoker compartment:

The 72.6mm "standard" boom length or thereabouts is used by most adult tandem couples. Tallest stoker to fit that compartment depends on setup. As length is restricted, the usual option is to position the stoker more upright. This boom length is the mid-length gates belt standard, so if you ever wish to use a gates belt for the timing side, you must stick with one of 3 measurements. Precision Tandems has a nice Gates Belt page posted with this info.

That said, event at 5' 2" my wife is a little cramped compared to her single setup. Her reach on a standard tandem cannot be as long as on a single and neither can the bar height be as low which results in her helmet and/or face hitting my back. Obviously there is little need for her to position as low for aero reasons on a tandem, but nonetheless she is very used to that single position and so it is the norm we base everything else from. Whenever the subject comes up, I remind her there are plenty of much taller stokers using the same same compartment size.

TandemGeek and some others on this forum have tandems with longer stoker compartments, and so their feedback on comfort and handling might be useful over conjecture.


Boost hubs:

I totally agree that boost hubs should make more sense than the old "tandem standard" 145mm rear, or 100mm front, especially when using dual disc brakes. Unfortunately there are very few rigid boost forks available that would fit on a road tandem. As you found, going to a custom fork is pretty much your only option. You are correct that the rear boost 148mm is actually a 141mm flange spacing. Quite a few of us that have gone to thru axle rears, are using only the 12x142mm hubs, so I think that boost 148mm is perfectly fine for most teams. The caveat to venturing away from "tandem rated" hubs is to ensure it has a steel axle and sufficient bearings and pawl configuration to handle the heavier tandem loads. Linda & I are a fairly lightweight team and do no loaded touring, so we have had no problem using standard hubs from White Industries for our road tandem.

qspencer

Thank you, that's quite helpful. Belt drive is probably more than I need to spend at this point, but it's worth designing for upgradability. My kids are clearly on their way to being tall but they are somewhat used to upright positions at this point, so I'm inclined to go with the 726 or 739 mm boom tube length and assume that will work for us for a while yet.

I hadn't thought about bearing load on the wheels. We chewed through the rear bearings on my wife's current tandem within the first 200-300 miles, but the bike was old and had clearly spent time in the weather when we bought it, so I'm not sure we were the cause. At the moment the max team weight for this tandem (wife and larger child) will be about 230 pounds. I'm inclined to go with budget-oriented MTB-designed Boost hubs and assume they are strong enough for now. If we use it enough and the kids get big enough, we can consider upgrades later.

merlinextraligh

The Co-Motion Java we're getting is spec'd with Co-Motion Branded Boost Hubs. Not sure who makes them, but I would imagine that Co-Motion is confident they'll hold up to tandem use.

Not sure if you can buy just the hubs from them though.

merlinextraligh

Have you considered a Co-Motion Persicope? The flexibility in sizing works well for growing kids.

qspencer

The periscope is what I should have bought 7 years ago instead of a Bike Friday. It served its purpose, but ultimately I found the frame a little flexy and the fit for me was not ideal (I bought it used). Now that my younger child is nearly 5 feet, everyone can fit on a full sized tandem, so the primary goal is for the stoker compartment to be long enough for the day (soon) when both kids will be taller than their mom.

qspencer

What crank will you be using? I'm trying to figure out whether the Boost width is going to work with normal road-width cranks, or whether I need something wider. The budget option is Sugino XD, which offers a lot of flexibility given the various available BB axle lengths.

merlinextraligh

^ Co-Motion specs it with FSA Gossamer Tandem cranks. So apparently it works with a standard road triple.



I wouldn't think the 148 spacing would be a problem. 145 rear spacing is pretty common on tandems, and Santana use 160mm.

twocicle

You can't call the Boost 148TA a 148mm spacing, cause it isn't. There are 3.5mm of the end caps buried into the dropout area, leaving 141mm between the dropouts. At 141mm spacing, that will move the cassette 2mm inboard toward the centerline when compared to a 145mm spacing.

Since FSA tandem cranksets are made to fit either 68mm or 73mm BB shells, a standard road BSA 68mm BB must use the provided spacers to fill that extra 5mm of axle length. Those spacers can be placed all on one side, so if you need to shift the chainline inboard, in most cases it can be done rather simply with these cranksets (caveat for chainstay and chainring clearances). Chainstay length is another factor that will play a roll in chainline and how the drivetrain might react. I would start with these cranks centered and see how the chainline & shifting works before thinking that offsetting the cranks inboard is needed.

merlinextraligh

Ok, I'll admit that I'm still trying to figure out Boost 148. I referred to it as 148 spacing because the hub is 148mm wide:

https://reviews.mtbr.com/wp-content/u...st-148-gfx.jpg

Here's a link to an article discussing the chain line implications: Tech Talk: Boost 148 explained - Mtbr.com | Page 2

d.manzella

I am currently waiting for a custom frame from Titan to be completed, so I can appreciate what it is you are considering. We also specified a boost rear hub. I am not comfortable with a titanium fork, so they are building just the frame. If you do end up ordering from China, it has been my experience that you need to make a concerted effort to avoid misunderstandings resulting from the language barrier. I sent lots of pictures of examples of what I wanted with respect to details. I also very carefully reviewed the frame drawing. It did take several iterations to get everything the way I wanted it. I can share that with you as an example if you are interested. We also want a custom stoker stem. Titan couldn't build it, so we are going with XACD for the stem. I just ordered it this week, for what I considered a very reasonable price of $168 including shipping.

twocicle

Ok, perhaps I'm splitting hairs, but my intended focus was more about frame spacing than hub axle width. The point was that a 148mm TA with its 3.5mm of dropout inset on each side, is more like a 141mm dropout spacing in QR terms that most here are more familiar with. I'm sure this could be stated better, but there you have it.

Juke41

Hi D.Man*****, I am also currently looking for a custom stoker stem, what was the process of ordering one with XACD ? Did you have to send a drawing ?

d.manzella

I emailed Alisa Huo (xatw@tw-metals.com) with the specs. She then had a drawing prepared for me to approve.

ksisler

I suspect confusion Could be reduced if folks would refer to OLD for regular hubs and e-OLD (effective Over Locknut Distance) in the case of the Boost items or similar hubs which hide a bit of the hub into the dropout. The articles referenced in Meline's post provides adequate tech data for the Boosters, either way. Having read what I wrote which makes up the term e-OLD does seem to fit the problem and it makes me smile to be inventive again [

twocicle

What we need now is for some bozo to come up with the 152mm (145 + 3.5 + 3.5) "tandem thru axle" rear hub. We'll call it eOLDx2. Yup, another stupid standard that few if any hub manufacturers will be interested in.

OneIsAllYouNeed

You can buy a few 150mm thru axle hubs today (Shimano Zee, DT Swiss, Hadley). With convertible end caps, you'd get down to 143mm QR, which would likely work on a non-carbon tandem frame built around 145mm QR. I'm not sure what the point of the exercise would be. This particular standard is not gonna last.

The bigger risk in building a tandem frame around any non-tandem standard will be finding hubs in 36, 40, or 48 hole drillings with strong axles and freehub bodies. The OP should be fine with 32 or 36h hubs given the lightweight team, but others going down this path might run into trouble.

tandembethesda

I'm intrigued with having a tandem custom built in China. I travel to China once a year and it would be nice to have a tandem there.

Does Wallty only build Frames or do they also assemble the whole bike?

qspencer

As far as I know they just build frames. I think they got into the business building frames to order for other brands and are now marketing custom frames direct to consumer.

For more information on the Chinese Ti builders, I recommend the blog called Spanner Bikes. It's a guy in the UK who has ordered Ti frames from Asia and documented his experience as well as that of other readers who have ordered frames. The market was originally dominated by XACD and Titanproduct, and then Waltly was started a few years ago by a former employee of one of them. The founder actually did an interview for the Spanner blog a couple of years ago. It's an interesting read. I believe there are others out there, but those 3 builders seem to be the most well known, and appear to have a reputation for good quality work, but with varying user experiences in terms of dealing with the language barrier and such. You have to know exactly what you want when dealing with them. Their expertise is in building to order, not so much in design.

merlinextraligh

Sorta like Santana?

ksisler

[Originally Posted by twocicle View Post
What we need now is for some bozo to come up with the 152mm (145 + 3.5 + 3.5) "tandem thru axle" rear hub. We'll call it eOLDx2. Yup, another stupid standard that few if any hub manufacturers will be interested In. QUOTE=merlinextraligh;19513438]Sorta like Santana?[/QUOTE]

Merline; Yep another brand hater. It frankly gets a tad boring after a while. What has it been 20 years or so since Santana decided a wider rear (160mm) wheel made sense for their customers. Now other brands are gradually widening, even some with oddities like the Boost (152mm). Time to get over it and quietly buy and ride what you want to ride. Be a fanboy for your favorite brand and talk to the good of it on its own merits, but no one cares any more about a fanboy's snarky whine about something they don't own but don't like just because. Sorry for poking back, but felt it was necessary...

merlinextraligh

Santana brings it on themselves. or specifically Bill McCready brings it on himself.

It's not just the 160mm spacing. Santana has to always do things differently, and then spin their marketing literature to convince you that their way is the only possible right way to do it. It's not only drop out spacing, but headset standards, disc rotor sizes, sweet 16 wheels ( the only possible low spoke count tandem wheel that could possibly be safe to ride.) etc. etc.

The fact that Santana deviates from industry standards should be a consideration in buying a Santana. I've spoken with tandem teams that have had breakdowns, such as a cracked captain's stem, that left them unable to ride on a tour for multiple days, which could have been instantly addressed at most any bike shop on tandems using standard headsets. Whether these issues are a deal breaker in buying a Santana is obviously up to the individual purchaser, but it should be a consideration in the purchasing decision.


What makes the Santana proprietary stuff annoying to me is their marketing literature. Over the years, Santana has gone to great lengths to explain why they way they do various things is the only proper method, not surprising from the author of "The Proper Method."

McCready deserves credit for basically inventing the high end tandem market in the U.S., but imho, there's also a lot of B.S. that he has rightfully been called on.

twocicle

Merline; Yep another brand hater. It frankly gets a tad boring after a while. What has it been 20 years or so since Santana decided a wider rear (160mm) wheel made sense for their customers. Now other brands are gradually widening, even some with oddities like the Boost (152mm). Time to get over it and quietly buy and ride what you want to ride. Be a fanboy for your favorite brand and talk to the good of it on its own merits, but no one cares any more about a fanboy's snarky whine about something they don't own but don't like just because. Sorry for poking back, but felt it was necessary...[/QUOTE]

FWIW, in the past we have owned 2 Santanas, and so both experience with those plus other tandem brands as well.

I think you may be erroneously referring to my post, since you are whining to Merline but it was he who mentioned 160mm spacing. My snipe was an off the cuff jest poking fun at the world of oddball "tandem standards" in general. Can you re-read it and tell me where my post contains any brand bashing or fanboy insinuation?

Over the years there have been plenty of adequate standards such wider hub spacing for mtb bikes (downhill especially), which for heavy tandem use may only need some internal tweaking to hold up (steel axles, more bearing and beefier pawls).

Thank you for the snarky reply. Looking forward to it.

merlinextraligh

I'm pretty sure it was aimed at me, and I'll admit my post was a snarky play off of your post.

But, the Gentleman (Ksisler) doth protest too much methinks.

waynesulak

It has been a while since Bill bashing made the forum. He is an interesting story. I think his personality and marketing helped when the tandem market needed it and now the market seems to have passed him by. I wonder how many forum readers are wondering now who he is and why he is being discussed.

I find his marketing distasteful, but I do have a lot of respect for what he has done. He built and operates a manufacturing company in California and does not just hang other peoples components on his bikes, He created his own supply chain for components made to specs he liked. In my mind his design changes are not proprietary because, as far as I know, anyone can build them royalty free. He just decided on new specs that he believed in and works and markets to get them accepted.

His company has lasted a long time, employed quite a few people, and is quite an accomplishment.