Tandem Cycling - 145 spacing vs 135 spacing
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07-19-09, 05:24 PM
Why is that the tandem spacing is much more than a single bike. I know that the dish is less and that it is stronger, but is it that much stronger? Is there any other reason except for the strength of the wheel? Does a hub made for a 145 spacing have the spokes further apart [left and right] or is it just a longer axle. I know that there may be several hubs but I was wondering what the 'norm' is.
I tried searching but was not able to find what I was looking for.
07-19-09, 05:35 PM
The less dish you have in a wheel the stronger it is supposed to be in theory or at least in the old days. Santana has 160 for this reason but not as critical I would think with the better rims and spokes of today.
07-19-09, 06:47 PM
The wider spacing on a tandem has room for a drum or disc brake in addition to less or no dish on the rear wheel. The less or no dish builds a stronger wheel.
07-19-09, 08:10 PM
If you're up for a long read, here's a link to a posting to the Hobbes list from Bill McCready back in 1996 that gives Santana's perspective on rear hub spacing and the evolution of the 145mm and 160mm standards: http://search.bikelist.org/getmsg.asp?Filename=tandem.9604.0451.eml
This link 'should' take you to one of the various volley's back-and-forth on the subject of 145mm vs. 160mm which, to this day, remains a polarizing subject:
The only conclusion that I've come to is that tandems can be built with everything from 130mm to 160mm to accommodate different requirements and wheel reliability comes down to the same thing: the wheels need to be built to support different requirements and wheels that use better-matched components (hubs, spokes & rim) and that are built with more attention to detail (proper spoke count for team weight, proper spoke tension and thorough distressing) will out last wheels that aren't.
So, while in theory a 160mm wheel with hub flanges that are spaced further apart than a 145mm hub's flanges hould have more lateral strength, if the spoke tension is a bit off on the 160mm wheel that theoretical additional strength will become a moot point when a spoke breaks and reliability comes into question.
As for current flange spacing, the 160mm hubs do tend to have wider-spacing vs. the 145mm hubs and many of the 145mm hubs used the same hub bodies as 135mm mtb hubs. All of these hubs can be used to build wheels that will offer very good lateral strength and durability and, as you'd expect, be found on wheels that weren't built well, were damaged or lost uniform spoke tension over time that have a history of breaking spokes.
tandem_rider is also correct in that the wider rear axles used on tandem hubs also allowed for easier installation of the Arai drum brakes.
07-20-09, 05:52 PM
Having a Santana with 160mm spacing I have experienced the benefits and drawbacks.
The only real benefit is a wheel that is likely to stay true longer.
I build my own wheels and have never had to retrue the 36 spoke 160mm rear.
The drawbacks are very limited choices in hubs and bottom brackets.
The bottom brackets have to be wider to acheive the proper chain line.
This results in the pedals being further apart (wider Q factor).
The wider Q factor has not been a problem for me.
I feel the limited choices of hubs and bottom brackets are a problem and prevent use of the lighter weight components. In the future I would not hesitate to use 145mm.
07-20-09, 06:18 PM
OTOH, our tandem has the older 120 mm hub spacing and has given us no wheel problems once we went to 48 spokes.
07-20-09, 08:47 PM
[Santana rant] Tangential Santana rant. When we first started looking to upgrade to a better tandem, we really wanted a Santana. To me, Santana was synonomous with high end tandem. Reading the various Santana literature including the bit about 160 mm spacing reinforced that view.
Ending up with a different brand tandem, I have to say we haven't seen any problems that Santana's approach to things, including 160mm spacing is intended to address.
[/ Santana rant]
07-21-09, 12:15 PM
I understand the Santana's approach to dishing and it makes sense. If there are not the aftermarket products to support that approach that is a drawback. My main concern is the 135-145 spacing and if it truely is a much stronger wheel. Yes, it is stronger but that much stronger? I did not even think of the spacing issues with a drag brake. I would think that with a wider spoke spacing that would make it even stronger but with the amount of tandems being sold that would probably be a loosing product for most companys. I am thinking about going to a 135 spacing due to all the additional options that are out there. Yes, they may not be tandem rated but if there is enough spokes and a good quality rim/hub I would be OK with it. Those that remember the 135 spacing standard [not me, I am new to this] was there that many issues with rear wheels?
07-21-09, 04:30 PM
All comes down to how much weight, type of riding etc how a wheel will hold up on a tandem.
160 mm doesn't guarantee a bullet proof wheel.
Years ago there was a Santana Tripplet that would show up on our Saturday rides with 3 big(6'3" or bigger) weighing over 200+ each. Guy in the rear at a stoplight shifted his weight slightly and the 48 spoke wheel buckled like a wet tortilla.:eek:
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