Tandem thoughts

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Re: Tandem thoughts

Postby rangersac » Tue May 07, 2013 3:25 pm

trianything wrote:Anyone know if I can switch to drops with usual brake/shifter levers with the current groupset


Gears no problem as the sprocket spacing and cable pull ratio is the same for an equivalent road setup. The issue will be the brakes. STIs are set up for calipers, so may not pull enough brake cable for full disc actuation.
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by BNA » Tue May 07, 2013 3:38 pm

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Re: Tandem thoughts

Postby rjk » Tue May 07, 2013 3:38 pm

rangersac wrote:
trianything wrote:Anyone know if I can switch to drops with usual brake/shifter levers with the current groupset


Gears no problem as the sprocket spacing and cable pull ratio is the same for an equivalent road setup. The issue will be the brakes. STIs are set up for calipers, so may not pull enough brake cable for full disc actuation.

you can replace the calipers with bb7 road discs calipers they have the right amount of pull for sti's, i have them on my cx bike.

Avid bb7's are arguably the most powerful of the cable discs out there and probably the easiest to setup, use the matching disc that goes with it as the disc pad is larger on the bb7's than the bb5's
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Re: Tandem thoughts

Postby jacks1071 » Tue May 07, 2013 3:50 pm

These are the brakes I use and recommend on our tandem, have had the Avid's and they arn't up to what I class as hard decending on a tandem.

http://www.pro-liteoz.com/store/index.p ... oductId=91
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Re: Tandem thoughts

Postby ironhanglider » Tue May 07, 2013 6:31 pm

trianything wrote:Hey I found this on Gumtree. Flat bar though. Anyone know if I can switch to drops with usual brake/shifter levers with the current groupset? The seller is not that specific but maybe enough info to know what is needed to convert to road.
http://www.gumtree.com.au/s-ad/woodvale ... 1018751644
On the thread, yes we are becoming empty nesters soon so the tandem becomes more viable in our situation. Hopefully won't open up any marital issues!!!
Cheers
CH



I second the input from Jacks1071. The avid's have plastic bits that can melt if you meet with the wrong conditions. This has been dealt with in tandemgeek's blog.

ISTR that Deon started selling the Bengal brakes because he wanted some for his own bike and the only practical way to get them to Australia was to buy a commercial quantity from Taiwan. A mate of mine bought some but decided that he wanted to do the nationals so we couldn't fit them (damn UCI rules). Time permitting, they will be fitted to his tandem for this weekend. (we really needed them last weekend :oops: )

Cheers,

Cameron
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Re: Tandem thoughts

Postby trianything » Wed May 08, 2013 1:25 pm

Rebuild sounds promising. I am guessing something simple like a 105 shifter/front and rear derailleur and new brakes might be the outlay? Can the clever folk let me know if I'm missing something... :oops:
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Re: Tandem thoughts

Postby rangersac » Wed May 08, 2013 3:54 pm

As long as whatever shifters/ brifters you use have the same indexing as the cassette on that tandem (i.e. 9 speed), then all you will need are the new shifters and brakes. You don't need to change the derailleurs.
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Re: Tandem thoughts

Postby ironhanglider » Wed May 08, 2013 4:00 pm

trianything wrote:Rebuild sounds promising. I am guessing something simple like a 105 shifter/front and rear derailleur and new brakes might be the outlay? Can the clever folk let me know if I'm missing something... :oops:


Bars, cables (both inner and outer, the routing is different so might require a different length), bar tape, probably a stem as well depending on personal and bar clamp dimensions. Not forgetting that the road bars put your hands further forward than flat bars.

Cheers,

Cameron
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Re: Tandem thoughts

Postby barefoot » Wed May 08, 2013 4:30 pm

Yep. You'll need tandem-specific cable inners. It's a looooooong way from the captain's handlebars back to the rear brake and derailer.

Especially for brakes, it's unlikely the existing cable that's cut to length for flat-bar shifters will be long enough to be routed through under the tape to a drop-bar shifter.

Then it's just a question of whether you're the right shape to reach a drop bar on that frame geometry. Remember, for a given stem, the hoods on a drop bar are several inches forward of where the flat bar used to be. Even taking into consideration that drop-bar riders are probably looking for a longer, lower riding position than flat-bar riders, they tend to make flat-bar specific bikes longer in the top tube to increase the reach... so flat-bar bikes tend to be very long if converted to drop bar.

tim
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Re: Tandem thoughts

Postby trianything » Wed May 08, 2013 4:38 pm

Thanks Cameron, Tim
Yes I had thought about the TTH length. I thought I might try the bike and decide if it was doable. Problem with short stems is the steering might get a bit too sensitive, expecially on a tandem I'm guessing.
Looking back at the thread, rangersac mentioned (thanks) that the sprocket spacing and cable pull ratio is the same so I'm guessing I could try leaving off new derailleurs and see how it shifts? Guess it's down to the fit from here.
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Re: Tandem thoughts

Postby drubie » Wed May 08, 2013 6:10 pm

Our trek was badly converted to drops but changing the stems it was easy to get everything where it should be. I bought the tandem specific stuff on eBay. Make sure you know what clamp sizes you need. The front 1 1/4 was the hardest. I ended up buying a nitto threaded to thread less adapter and now use a normal thread less stem. It works very well even with a slightly shorter one, no twitchiness at all.
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Re: Tandem thoughts

Postby jacks1071 » Wed May 08, 2013 10:38 pm

trianything wrote:Rebuild sounds promising. I am guessing something simple like a 105 shifter/front and rear derailleur and new brakes might be the outlay? Can the clever folk let me know if I'm missing something... :oops:


I run an MTB rear mech, long cage type so I can run an 11-34 cassette. Very handy on a tandem so you don't need to do as much front shifting.

Also get wide bars, I use 42cm on my roadie but 46cm on the tandem. Tandem requires much more steering so you want as much leverage as you can get.
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Re: Tandem thoughts

Postby trianything » Thu May 09, 2013 11:53 am

Cheers for the advice all. The bike in question only as a single chainring (39T) rear is 11-32. Prob ok up the hills but not down for a roadie? Mind you I'm not sure if there is some kind of gearing conversion through the stoker cranks.

I had an interesting experience when I tried standing on a tandem once. Mrs stoker a bit taken aback :lol:
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Re: Tandem thoughts

Postby find_bruce » Thu May 09, 2013 12:43 pm

trianything wrote:Cheers for the advice all. The bike in question only as a single chainring (39T) rear is 11-32. Prob ok up the hills but not down for a roadie? Mind you I'm not sure if there is some kind of gearing conversion through the stoker cranks.

I had an interesting experience when I tried standing on a tandem once. Mrs stoker a bit taken aback :lol:

Perhaps I am misunderstanding you, but it seems you might be confused as to how gearing on a tandem works - you want the same size gear for the timing chain between the captain and stoker. When I was a kid some neighbours had a homebuilt tandem that ran something like a 53 captain crank to a 42 stoker crank - ie when the captain had a cadence of 90, the stoker was spinning along at 113. It didn't work!

If you are still talking about this bike on gumtree, it has a triple crankset with a standard cross over drive.
Image

The sync chain is on the left (with a single gear front and back) while the drive chain on the right operates just like any single bike
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Re: Tandem thoughts

Postby trianything » Thu May 09, 2013 2:50 pm

Crap you're right. I admit to having no clue about what happens to the drivetrain between the captain's cranks and the rear derailleur - never looked that hard. Your reply clears that up. No trouble sorting out normal road bikes myself but bit of a learning curve for this tandem lark. Partly self-induced embarrassingly. I'm going to go look at this bike.
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