148 Boost or 142TA?
 

Looking at having a tandem built and have the option of 148mm boost or 142mm thru axle.

Pros and cons?


As a side question, what rear dropout spacing does Co-Motion use on their road tandems?

For decades 145mm OLD q/r was the Tandem standard, along with Santana's outlier 160mm q/r. Everything has gone kerfluy in the last 5+ years in the non-tandem world with Thru-axle, Boost and probably other 'standards' vying for pride of place. Most of us are well out of it. Our rigs will outlive us and the 145mm q/r will co-exist side by side with all the newfangled running gear for decades more yet. There are no pros and cons. Boost and Thru-axle running gear has a better cost/benefit ratio to your Tandem builder because that is what is hot right now. All other things being equal, a wider OLD is "better" for rear wheel strength. 142mm seems like a step backwards in that respect. All depends on who is riding it and how. But it really sounds like you should be thrashing this out with your builder. FWIW.

just go for 148mm

Most CoMotions from the last 25 years or so would have 145mm quick release spacing, though I'd imagine they have built some to different standards over the years.

142TA is going to give you a wider range of hub choices than 148, but would, everything else being equal, result in a weaker wheel as the narrower spacing would mean more dish required. 145QR would be effectively equal to a 152 thru axle, so would theoretically be a stronger wheel, but whether this practically matters to you will depend on your team weight and what you are wanting to do with the bike. I just got one built for road riding and went with 142.

I've been riding QR so long that I had little interest in a new "standard" but I like it more than I expected. I find the TA to be easier to put the rear wheel into the bike and, with lawyer lips requiring unscrewing the QR, there's no great disadvantage to the TA in pulling the front wheel off and on either.

I just purchased a Co Motion Java it has boost hubs they are 148 x 12 rear and 110 x 15 for the front. The TA thread pitch is 1.5”.

I would go for 148 Boost because it's a popular standard and there are hubs from Shimano, DT Swiss, and Hope. We use the White Industries 148-12 TA with 28H and it works well. I also use 148-12 TA on my Specialized Vado SL commuter bike.