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  1. #1
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    Mountain tandem fit question

    After some time on a road tandem,I'm considering a mountain tandem.I have many years of off-roading on a single and I know that fit/weight distribution are critical for climbing and endo resistance on a single.

    My question is:Given a choice of the captain using an ~11cm stem vs. a ~13.5,which is the better choice? I'm trying to balance the desire for a shorter wheelbase VS reducing the weight/stress on the fork.I don't seem to be able to lift or unweight the front much,and it seems the front may jam less with the shorter stem.I would start on a rigid fork.

    Part B: As in singles,do stokers like/want/need all the room they can get?Again,it stretches the wheelbase.

    I have a good relationship with the local Cannonball dealer and thats probably where I'll start,and if needed tweak the fit and other things on the next purchase.Since I ride in West Virginia,I won't consider rim brakes.

    Ideally,I'd like a 29'er/700c tandem with a rigid fork.I switched from 26 to 29 on my single and wont go back.However,29"tandem mtb's are quite rare.The only stock one I know of is the Vicious Jeepster,which exceeds my budget.No proof,but I think 40 -48 hole wheels will be OK on a 29.

    Thanks,dan
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  2. #2
    Time for a change. stapfam's Avatar
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    Looking at this thread, I am wondering what sort of Tandem you want. Is it a Mountain bike that is to be used offroad, or a More comfortable tandem to be used on the road? They will be different beasties.

    As to lifting the front end, or even unloading it, That will be difficult, I would almost say impossible. Tandems are heavy, as all pilots have found out, so trying to get a lighter front end is admirable, but doubt as to whether it will have any effect on the handling of the bike. If it is gentle tracks and trails that are contemplated then a rigid fork will do but any thing a bit lumpy or tecnical and front suspension is almost a must.

    Mountain Tandem side now- If it is an offroad tandem you want for use offroad, then look at the Cannondale MT as a starter. The only thing I would change on this initially would be the fork, and that would be to a suspension fork and 20 mm axle. Then onto wheels- Offroad requires strong wheels, and rims and even tyres. 26" are strong and can even be as low a spoke count as 36. They cannot be lightweight and my only experience of 29ers is that the wheels would not be strong enough. And the same for 700's.

    Give us a few more clues as to how the Tandem will be ridden and let the arguments as to choice begin.

  3. #3
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    It will be used for knarly off road mtb'ing.Rocks,roots,log crossing,etc.We have been using our Cannondale road tandem for some light mtb'ing,but rear wheel traction is a problem(it accepts tires in the 40's).That is what led me to the weight distribution/wheelbase question.Steep,muddy climbs are the norm here in the winter,and I was hoping to simplify with a rigid fork,but I can see that suspension is close to a must.

    700c and 29 are the same rims,and there are a few tandems in service by members of the 29'er forum.Wheels are holding up OK.My thinking was that since they roll over things better,a suspension fork may be less necessary.I'm leaning toward a long front to have less weight on the fork,and a short rear to keep the wheelbase short and try to get more weight on the rear wheel for climbing traction.Truth is I have no freakin idea....

    If money were no object,I'd probably get a DiVinci aluminum29'er...I think the ICS would be wonderful offroad.

    dan
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  4. #4
    Senior Member Brian's Avatar
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    No offense, but you summed it up at the end of your last paragraph. Any traction problems encountered will be due to tire selection, not frame geometry. And if you've got mud, you'll want a nice wide fork, with plenty of tire clearance. A skinny rigid fork won't cut it. Also, any advantage a 29" wheel has on singles is probably lost on a tandem.

    Re: Stoker compartment. Will your wife/partner be the stoker? Ask them how close they want to be to your, um, saddle. Unless you're having a custom frame made, they'll have to deal with whatever the stock dimensions are. But if you don't know exactly what you want, custom is not necessarily the way to go.

    I'd look for a lightly used Cannondale, since you'll need to replace the headset, stem, fork, and wheels right away. From there, you'll probably look at swapping seats and bars, along with a bunch of other parts as your taste/needs dictate.

  5. #5
    hors category TandemGeek's Avatar
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    Unless you're having a custom frame made, your stem length should be only determined based upon the best "fit" for the given frame's top tube length and head / seat tube angles. Moreover, trying to optimize a tandem's weight distribution fore or aft by 1" just isn't worth fiddling around with; remember, the thing has a 6' wheelbase.

    As for starting on a rigid fork, unless you were trying to save money and have already decided that the C'dale MT1000 is the right bike to start with, I'd think long and hard about that one unless you're going to keep your off-road adventures off the more gnarly single track. For technical stuff, you really want the extra control and stability of a suspension fork given that you've got someone's butt other than your own to consider if and when you dump it... and you will dump it if you play hard. The weight of tandems coupled with the need to ride further out from the ideal single bike line on corners often times puts your front wheel on less firm soil or berms that can easily wash out from under your front tire and that, more than anything else, is what tends to trip us up.

    As for stoker compartments, our Ventana has a stoker compartment that's about 30.5" long and it's a small size frame. However, even with what is about an extra 2.5" of stoker compartment -- which Debbie really appreciates since she doesn't have her face planted in my Camelbak whenever I hang my butt off the back of the saddle during drop-ins -- the wheelbase is only about an inch longer than a Med/Small Cannondale. In fact, Cannondales with 28" stoker compartments range in wheelbase from 69.6" to 73.2", whereas the Ventanas with the 30.5" stoker compartments range in wheelbase from 71.4" to 73.4". One or two inches does not make or break off-road tandem handling for the average recreational or sport rider. Anyway, the point of this is, whether you buy a Cannondale or Fandango, you get a 28" stoker compartment and a tandem that's got a wheelbase around 71" long, plus or minus 2".

    Disc brakes are a no brainer these days. 29"... heck, buy a used Cannondale RT1000 with 700c wheels and you'll have your 29 incher. Frankly, I don't get the attraction other than being the next cool thing but to each their own. However, that said, there are a couple tandem builders fiddling with 29" bikes, to include Ventana's Sherwood Gibson. I'd talk with them to see if they think the design will translate well to tandems. Frankly, I'd rather opt for the more stout 26" wheels on a mountain bike with a gross weight of nearly 300lbs.

    Bottom Line: If you've got $2,300 burning a whole in your pocket or home equity line a Cannondale MT1000 would be a great 1st off-road tandem. However, you'll also find a few older C'dale MT2000 and MT3000 frames, even some with C'dale Moto FR-T dual crown fork on the used tandem classifieds for around $1,800 which are also great values. There's also MTBTandems.com's house brand, the Fandango. It was designed to take best features of a Cannondale MT and the Ventana f/s tandems and meld them into an affordable frame / bike package, which i believe Alex has accomplished. There are a few other all terrain tandems floating around that you can buy but my bias is definitely skewed towards more current designs and equipment found on both new and lighly used tandems.

  6. #6
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    "the need to ride further out from the ideal single bike line on corners often times puts your front wheel on less firm soil or berms that can easily wash out from under your front tire and that, more than anything else, is what tends to trip us up."

    Thats useful info.I hadn't thought about that,but it makes sense that a tandem doesn't have the flexibility of choosing a line that a single does.

    Since I have 2 Cannondale road frames,I've already experimented with large tires-42's,but thats not big enough.Thats all that will clear,so we are kinda limited.I think of it as a cyclocross tandem and those barrier dismounts/remounts are kinda slow...

    After ridind 29's for 3 years I really hate to go back to 26,tho.I'll probably get an X/M Cannondale and decide what I like/don't like and then get a custom.

    dan
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  7. #7
    hors category TandemGeek's Avatar
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    Quote Originally Posted by dfcas
    After ridind 29's for 3 years I really hate to go back to 26,tho.I'll probably get an X/M Cannondale and decide what I like/don't like and then get a custom.
    Whatever happened to the father of the 29", Wes Williams? He was all over the place on NPR, bike rags, WSJ, etc.. back in the hey-day of the initial 29" movement and in addition to his Willits brand Scorcher sold by his Crested Butte Bicycle Company he also offered a 29" off-road tandem, although not as well thought out as the Vicious two-fer.

  8. #8
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    http://forums.mtbr.com/showthread.php?t=135138

    Timely question-there was just a thread on him on the 29 forum.short version-he tired of working long hours for little pay and shut down,moved to Austin TX,began selling cars.It -looks- like he's coming back in the biz.

    I talked to my C'dale friend today and he thinks I should size up to use an 11cm stem and get the med rear to give the stoker a 29.1 toptube,so if I go C'dale it will be for a X/M.I m sorely tempted by the DaVinci,tho. The geo seems very different,however.73*head angle,short TT.I kinda think maybe it doesn't matter.

    Tandemgeek-thanks for the time and info you put into this forum and the other places I've seen you post.You should be the official industry analyst!

    dan
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  9. #9
    Time for a change. stapfam's Avatar
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    For any off road Tandem that is going to be ridden hard- not necessarily aggressively, but hard enough to get the adrenalyn going- 4 things from others Riders set up of their bikes should point you in the right direction. Front suspension- The harder you ride, the better suspension and strength in the fork is required and most of us have changed over to 20mm axle. Stokers comfort is required so Suspension post definitely. Brakes for offroad should preferably be Disc brakes, but you can get by on V Brakes. Finally wheels- These have to be strong. Even by good quality road wheels they have to be strong. The reason a mountain bike has 26" wheels is that they are strong enough. When you get to a mountain Tandem- they have to be stronger. Not necessarily overbuilt, but You are thinking of a Mountain Bike Downhill wheel to get up to the requires strength. At least it has to be of "Freeride" quality so lightweight Hubs and Rims are out.

    These Tandems will take a lot of punishment and it is not worth taking a chance on component failures. Think strong and that is the confidence your Tandem will give to your riding.

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