Tandem Cycling - New Tandem Build - English Cycles

Hi All,

Here's the new tandem that I am having built (see attached pdf). Here's the specs:

Frame - English Cycles Tandem, titanium midtubes
Fork - ENVE - Road 2.0 Tapered 1.125” to 1.5”
Headset - Cane Creek 40 ZS44/EC44
Captain Seatpost - Thomson Elite 27.2mm, 330mm, silver
Stoker Seatpost - Eriksen titanium, 27.2mm, 400mm, pewter clamp
Captain Saddle - Specialized Romin Expert
Stoker Saddle - Selle San Marco Aspide Glamour
Captain Stem - Deda Elementi Zero1, 130 mm
Captain Handlebar - FSA Wing Pro Compact, 44cm
Stoker Stem - Deda Elementi Zero1, 130 mm
Stoker Handlebar - FSA Wing Pro Compact, 40cm w/ stoker pegs
Shifters - Record Ergopower 10 spd
Front Derailleur - Campagnolo Comp Triple w/ Braze on adaptor
Rear Derailleur - SRAM X-9 10 Speed, Grey w/ white graphics
Brakes - FSA SL-K, Black w/ white graphics
Crankset - Davinci Tandem (54/42/30), 175 mm Captain, 172.5 mm Stoker
Bottom Brackets - Davinci Ti, Captain-107mm, Stoker-113mm (49.6mm Chainline)
Crank Bolts - Self Extracting Crank Bolts x 2
Chains - Wipperman Connex 10S0 x 3
Cassette - Ultegra 11-28
Wheels - Rolf Prima Vigor Tandem

Design is primarily for fast group rides and racing with an occassional century. Components have been selected to be relatively light weight without breaking the bank.

Anything else I should consider before giving the final go ahead? I'm particularly interested in any suggestions for maximizing shifting performance.

Thanks!

wow i can't wait to see this. what will other tubes be? never saw a photo of an english tandem. his road bikes are wild, check out ww forum--lots of his builds are posted there. that silver internal di2 build he did was pretty sharp.

JSNYC - The other tubes will be steel. The only tandems that Rob has built to date are recumbents, so that is why you have never seen a photo. You can see pictures of the recumbents and his other bikes at englishcycles.com. You will have to wait until August to see the final build, but if there is enough interest, I will keep this thread up to date with progress.

sounds nice!

yes post build pics along the way! yours will be his first road tandem? when does he start doing the actual frame construction? will he send photos to you? definitely post those--that's my favorite thing to look at & admire. the final build is great, yes, but i really like seeing all the steps it takes to get there. have fun and i'll flag this thread--looking forward to seeing the progress. :thumb:


JSNYC - The other tubes will be steel. The only tandems that Rob has built to date are recumbents, so that is why you have never seen a photo. You can see pictures of the recumbents and his other bikes at englishcycles.com. You will have to wait until August to see the final build, but if there is enough interest, I will keep this thread up to date with progress.

Photos indeedy. :) How are the Ti tubes going to be mated to the steel bits? I would assume epoxy bonded... though I do seem to recall a Ti road frame having been silver brazed way back when...

JSNYC - I hope to have pics of the construction process and will post them here. Yes this will be Rob's first road tandem. Construction is supposed to start in May.

StanleyJ - The Ti tubes will be clamped in place. This will allow them to be removed for travel. The tandem will fit in two S&S hard cases. Also, by having the Ti tubes removeable, we could replace them with SS tubes if we wanted to "tune" the frame characteristics.

A couple of comments:

The stoker bars look to narrow, you may want to check their width.

When I was researching a new set of wheels the consensus was that the Rolf wheels were problematic, we went with Topolono and we are very pleased with their performance. We have over 1500 smiles on them now.

We are using a complete Shimano drivetrain and the shifting is outstanding. New Shimano tandem cranks, 6703 shifters, DA triple FD and RD. Ultegra 11-28 cassette.

Wayne

Hi Wayne,

Thanks for the comments! This kind of feedback is great.

Stoker bars - We currently have 38cm bars on our Cannondale and my stoker prefers narrow bars. From what I understand, the FSA Wing Compacts are measured at the drops and are narrower at the tops, so we have selected 40cm.

Wheels - I would love to have a set of Topolinos as everything I have read about them is really positive. Unfortunately, we already own the Rolfs and new wheels aren't in the budget. Maybe in the future I will have the funds to purchase some. I would also be interested in the Spinergy wheels. Ahh, to have unlimited resources.

Crankset - I looked hard at the Shimano cranks after you posted about how well they shift. There were three things that made me go with the Davinci cranks - 1) Large price difference, 2) Stoker cranks not available in 172.5 and 3) 54/42/30 Gearing not available. How do you find the chainline at 45mm? It seems like it would cause a lot of chainrub when using the lower half of the cassette with the little or middle chainring.

Shifters - I chose the Record shifters because my builder had a slightly used set for a good price. This saves quite a bit of money and and a few grams of weight. (I have used Campy, Shimano, and SRAM and IMHO Campy is slightly better than Shimano with SRAM being inferior)

Derailleurs - I selected the Campy Comp Triple, but wonder if a Shimano FD might be better. I selected the SRAM RD based on TandemGeek's reports from his testing on their Calfee. Also, my builder has successfully used Campy Shifters with SRAM derailleurs.

Thanks again for your comments!

Are you both tall? Your diagram suggests a 38" captain inseam and a 36" stoker inseam. Why such a short stoker seat tube (and such a long stoker seat post)? Why such low handlebars for both positions? Your stoker will have his/her head in the captain's spine from the looks of this.

There's a shop near us that does "positioning", not "fitting"; their approach is to put the rider(s) on a fully-adjustable trainer and tweak for best power/comfort compromise, then build a bike to match that. He has no set routine, but it seems to me that most of his creations end up with noticeably "relaxed" seat post angles, i.e. closer to 65' than 72'. His comment on my wife's discomfort is to move her saddle back 3-4", though he won't take our money and do a positioning on her unless he feels there's a way he can actually implement the changes he expects to discover. If nothing else, don't rely on Knee-Over-Pedal-Spindle as there's no anatomical reason to do so.

What with the components you already have, and the not-breaking-the-bank mandate, there isn't much scope to advise any changes.

With the 172.5 mm stoker crank imperative, the options in external-bearing cranks are limited to FSA and Lightning.

What is the terrain of your rides? Steep climbs and descents? Likely not, with no disc brakes.

Build sheets are best put on spreadsheets, so that you can change the weight and costs.

Looks like it will be a nice bike.
We use 42cm FSA compact bars with cane creek dummy brake levers. This has minimal clearance between stokers thumbs and my legs when she is using the brake hoods. But we do use a 100mm stoker stem so your 130 will help a bit.
Also I would question the use of a triple crankset. I realize everyone seems to use them on tandems but I think if you are a strong enough team to race and keep up with fast group rides you should be alright with a double. If you are with a group of fast singles and you need a triple to get up a hill you will be off the back very quickly.

Are you both tall? Your diagram suggests a 38" captain inseam and a 36" stoker inseam. Why such a short stoker seat tube (and such a long stoker seat post)? Why such low handlebars for both positions? Your stoker will have his/her head in the captain's spine from the looks of this.


Thanks for the good questions!

I am 6'-0 1/2". My wife is 5'-8 1/2". We both have relatively long legs (especially my wife). How did you arrive at 38" and 36"? I don't get anything close to that using either the Lemond formula (88.3% of inseam = dist. from cen. BB to top of seat) or the 109% rule (109% of inseam = distance from pedal spindle to top of seat).

The short stoker seattube is to maximize the extension of the stoker seatpost to provide some passive suspension rather than utilize a suspension seatpost. It also makes the frame more compact and therefor more tortionally rigid.

The handlebar positions mimic our single roadbikes. We have arrived at these positions through years of experimenting and one professional fit that made some very minor changes to where we were already at. With these positions we can ride for 4 or 5 hours without issue and feel like we develop good power. However, we haven't ever been "positioned" as you describe. Lately we've been riding with a guy who does fits, and his on the bike assessment has been that we look good on our bikes.

Good assessment on the stokers head on my spine. We currently ride a Cannondale, and my wife is cramped and uncomfortable. We initially planned to go from a 28.5" to a 30" stoker compartment, but ended up with 31". On our Cannondale, when we really put the power down, her helmet rests on my tailbone as she drops her head when she pedals hard. The added pressure is quite uncomfortable. The extra 2.5" should eliminate that. It is likely that we will adjust her position slightly from what is shown, but we figured we would start from where we are at now on our singles.

What is the terrain of your rides? Steep climbs and descents? Likely not, with no disc brakes.

Build sheets are best put on spreadsheets, so that you can change the weight and costs.

We do ride some steep terrain (up to 15%), but it generally isn't too long. Based on some information on BF's and Tandemgeek's blog discussing the relative advantages of rim, disc, and drum brakes, we have chosen to go with rim brakes. I haven't been convinced that disc brakes are the way to go on a tandem. However, we also have the option to add a drum brake if we are going to be in some really steep terrain. I should also mention that we are a 290 to 300 lb team depending on the time of year and how much we have been riding.

I agree completely - spreadsheets are ideal for build sheets. In fact, I have all of this information and more on one. For some reason I couldn't get it to play nicely with this forum, so I ended up copying the pertinent information into the body of the post.

I would question the use of a triple crankset.

I've read with fascination as people have debated the double vs triple for tandems and have ended up in the "triple camp" (if there is such a thing). When I started planning this build, I was going to use a double (53/38) and a wide range rear cassette (11/36), but we really don't like the wide jumps that come with that set-up. We live in an area with lots of hills and there are times when I know we will want the granny ring to bail out to. On our Cannondale (52/42/30 - 11/28 9spd) we find that we ride between the 52/42 most of the time, with an occassional need for the 30. When we do drop into the 30, we often are using the middle of the cassette rather than the really big cogs. We do live on a hill with some 12% grade, so at the end of a long ride, it is really nice to have the lower gears to spin up the hill on the way home. On the groups we have ridden with, we are generally not last up the hill, and sometimes can almost keep up with the hillclimbers - probably because we had the opportunity to put the hurt to them on some rollers before hand :)

Just wanted to say THANK YOU to all of you who had made comments so far. I'm starting to feel like a bit of an a$$, because I've not changed anything so far based on the comments. However, this has been really helpful for me to review my selections and try to express the reasons behind them. If you think I'm offbase somewhere, please feel free to tell me without concern for offending me. I find an intense discussion quite refreshing sometimes (as long as it doesn't stray into name calling).

Thanks!
Ryan

rhino, many folks here are super knowledgeable on tandem stuff. i mean, RIDICULOUSLY good knowledge. since my wife and i are total beginner tandem riders (although i've been riding or occasionally racing on road for 25+ years), they helped me with so many questions i wouldn't have known to ask when i had my first custom tandem done--which wrapped up just recently.

luckily, my builder has built many, many tandems, and from what i gleaned here i could have intelligent conversations with him, which was really helpful. :thumb:

How do your hips/quads fit between such a narrow stoker bar? Our stoker bar is a 46mm deda (outside to outside), and I still get the occasional rub passed her hands when she is using the stoker hoods. I am not a big guy, tall nor wide..

Only caveat would be if the stoker stem is long enough to put her bars entirely behind you. Perhaps that is the case?

How do your hips/quads fit between such a narrow stoker bar?

I posed this question to my wife. She immediately responded, "It's because you have a micro butt!" LOL

Of course, I wanted to quantify this, so we measured the width of my hips. Answer - 33cm out to out. Apparently I have unusually narrow hips.

The bars also do sit a little behind me, but I do occasionally feel my leg brush against her hands - or maybe it is her hands brushing against my butt ;)

StanleyJ - The Ti tubes will be clamped in place. This will allow them to be removed for travel. The tandem will fit in two S&S hard cases. Also, by having the Ti tubes removeable, we could replace them with SS tubes if we wanted to "tune" the frame characteristics.

Hmmm. Intriguing! So the Ti tubes directly "clamp" to the steel "lugs"? Rather than S&S couplings where a Ti one will couple to a steel one (I believe for S&S, the torsion coupling bit is always steel anyway, right?)... or was that what you meant anyway?

Still, mucho looking forward to the frame-construction/build-up...

PS: With S&S, guess you could even get some carbon tubes (with couplers fitted) from Calfee? ;)

I am 6'-0 1/2". My wife is 5'-8 1/2". We both have relatively long legs (especially my wife). How did you arrive at 38" and 36"? I don't get anything close to that using either the Lemond formula (88.3% of inseam = dist. from cen. BB to top of seat) or the 109% rule (109% of inseam = distance from pedal spindle to top of seat).


I just did some napkin math - 100% of inseam = distance from pedal spindle to top of seat. I figure with knee slightly bent, the height of the shoe is washed out, and honestly I just wanted to put some numbers "on paper" to drive the discussion (which thankfully you've confirmed that you thought through).



The short stoker seattube is to maximize the extension of the stoker seatpost to provide some passive suspension rather than utilize a suspension seatpost. It also makes the frame more compact and therefor more tortionally rigid.


What haven't you thought of? With this design, I'd suggest you CONFIRM that your desired seatpost can be that high, maybe even check to see if there's an alternate product on the market that also can be that high. If you're doing a custom tandem that could last 20 years, you don't want to end up with a design that snaps seatposts (and just in case it does, you want to have a different product to use instead).



The handlebar positions mimic our single roadbikes. We have arrived at these positions through years of experimenting and one professional fit that made some very minor changes to where we were already at. With these positions we can ride for 4 or 5 hours without issue and feel like we develop good power. However, we haven't ever been "positioned" as you describe. Lately we've been riding with a guy who does fits, and his on the bike assessment has been that we look good on our bikes.

Good assessment on the stokers head on my spine. We currently ride a Cannondale, and my wife is cramped and uncomfortable. We initially planned to go from a 28.5" to a 30" stoker compartment, but ended up with 31". On our Cannondale, when we really put the power down, her helmet rests on my tailbone as she drops her head when she pedals hard. The added pressure is quite uncomfortable. The extra 2.5" should eliminate that. It is likely that we will adjust her position slightly from what is shown, but we figured we would start from where we are at now on our singles.

My only thought then would be to rotate your stoker "up" - pull the stoker saddle back perhaps 3", then bring the stoker bars up the proportionate amount, and you may then be able to shorten the stoker box AND give her more ability to see over/around you.

P2: English tends to build road bikes with ginormous ISP's and/or a lot of slope. It'll be interesting to see how this translates to tandem design. Check this out:

http://www.englishcycles.com/cat/custombikes/roadbikes/#

Rhino919: did I read your post correctly in that the ti tubes will be coupled to the steel tubes? Sounds interesting, can't wait to see how that is going to be fabricated. Sounds like a great deal of work.



What haven't you thought of? With this design, I'd suggest you CONFIRM that your desired seatpost can be that high, maybe even check to see if there's an alternate product on the market that also can be that high. If you're doing a custom tandem that could last 20 years, you don't want to end up with a design that snaps seatposts (and just in case it does, you want to have a different product to use instead).

I agree completely - spreadsheets are ideal for build sheets. In fact, I have all of this information and more on one. For some reason I couldn't get it to play nicely with this forum, so I ended up copying the pertinent information into the body of the post.

Just so you know... you can upload the spreadsheet to Google Docs: https://docs.google.com/

Obviously, for the public, read-only version... you'd want to remove/censor any personal data/information by the way of names, address and the like. :)

I would prefer a longer seat tube for the stoker. Mainly because I think it would look better. Looong seat posts look a bit like they should be on a mountain bike rather than a road bike to me.
Also unsure about having your top tube length so that you need a 130mm stem. I guess it is ok if you are absolutely sure on the positioning, but if you decided to move your saddle back a bit or just wanted a bit more reach it doesn't give you much room to move as far as getting a longer stem.

So the Ti tubes directly "clamp" to the steel "lugs"? Rather than S&S couplings where a Ti one will couple to a steel one (I believe for S&S, the torsion coupling bit is always steel anyway, right?)... or was that what you meant anyway?

The Ti tubes fit into a steel socket that clamps around them. This is way less expensive than S&S couplers. It also allows the bike to "stretch" slightly to set tension in the timing chain and eliminate the need for an eccentric BB. However, I would imagine that assembly will be more difficult than with S&S couplings and the connection isn't as positive as with S&S. You can see pictures of the tube in socket method applied to a recumbent tandem here (http://www.englishcycles.com/custombikes/custom-tandem-recumbent/). Bike Friday (http://www.bikefriday.com/bicycles/tandem)also uses this design on their tandems.


PS: With S&S, guess you could even get some carbon tubes (with couplers fitted) from Calfee? ;)

The design allows for multiple tube materials (steel, ti, aluminum, carbon, bamboo, ...) All you have to do is get the right diameter, cut it to length, and clamp it in place. A carbon tube might need an insert at the ends to strengthen the clamping area?


Still, mucho looking forward to the frame-construction/build-up...

Me too!!!

I just did some napkin math - 100% of inseam = distance from pedal spindle to top of seat. I figure with knee slightly bent, the height of the shoe is washed out, and honestly I just wanted to put some numbers "on paper" to drive the discussion (which thankfully you've confirmed that you thought through).

Yes, I've spent lots and lots and lots of time thinking about this design. My wife says I am obsessed! :) Thanks for asking questions to keep moving the discussion forward.


With this design, I'd suggest you CONFIRM that your desired seatpost can be that high, maybe even check to see if there's an alternate product on the market that also can be that high. If you're doing a custom tandem that could last 20 years, you don't want to end up with a design that snaps seatposts (and just in case it does, you want to have a different product to use instead).

Confirmed - We will have approximately 300mm of seatpost showing which leaves another 30mm to the min. insertion line. Of course we also have to make sure that the seatpost extends below the junction of the top tube and seat tube. There are several other options for 400mm+ seatposts - Thompson (410mm), Easton EC70/90 (400mm), BBB Longscraper (450mm). Since my wife only weighs 125-130lbs we can generally use anything we want for her without worrying about breakage. On our singles, her chains and tires last at least twice as long as mine.


My only thought then would be to rotate your stoker "up" - pull the stoker saddle back perhaps 3", then bring the stoker bars up the proportionate amount, and you may then be able to shorten the stoker box AND give her more ability to see over/around you.

We started with a position something more like what you describe on our Cannondale, and have migrated away from it. Even when she takes her hands off of the bars and sits upright, she really can't see over/around me. In the end, the position shown is what she has asked for. And we all know, what the stoker wants is what the stoker gets :)

Rhino919: did I read your post correctly in that the ti tubes will be coupled to the steel tubes?

I think I have answered this in my response to StanleyJ. If it still doesn't make sense, let me know and I will try to describe better :)

Great to have people trying new things. Keep us informed.

I would prefer a longer seat tube for the stoker. Mainly because I think it would look better. Looong seat posts look a bit like they should be on a mountain bike rather than a road bike to me.

I actually prefer the highly sloped TT design with a long seatpost, but appreciate that there are many that don't. I would guess that there will be those that look at the final product and think how much better it could have been if they had just......


Also unsure about having your top tube length so that you need a 130mm stem. I guess it is ok if you are absolutely sure on the positioning, but if you decided to move your saddle back a bit or just wanted a bit more reach it doesn't give you much room to move as far as getting a longer stem.

Good comment! I've spent some hours "agonizing" over this decision and hope that I have gotten it right. One advantage of a tandem is that you can use a long stem without worry for overloading the front wheel. If anything, I would expect to shorten my reach rather than lengthen it as my body ages.

rhino--that's gonna be pretty darned cool if it works as intended. I'll wait to see photos before asking how the clamps will be made and oriented or other such details. Pics are worth a lotta words. As odd as it otherwise sounds, it's almost like you could "tune" your ride depending on whatever tube you felt like sliding in there. Cool concept. Do the clamps have an expected lifecycle of opening/tightening?

some of english's bikes are really far out there, but he's not afraid to take things on and redefine the "norm." plus, it sounds like he's got the riding & racing chops that lend a lot of credibility. it's fun to watch what he does. lots of posts over on the ww forum of his creations.


You can see pictures of the tube in socket method applied to a recumbent tandem here (http://www.englishcycles.com/custombikes/custom-tandem-recumbent/). Bike Friday (http://www.bikefriday.com/bicycles/tandem)also uses this design on their tandems.

Do the clamps have an expected lifecycle of opening/tightening?

I would expect the life cycle to be infinite. I don't see how it would be any different than the seatpost clamp on a steel frame.

How do your hips/quads fit between such a narrow stoker bar? Our stoker bar is a 46mm deda (outside to outside), and I still get the occasional rub passed her hands when she is using the stoker hoods. I am not a big guy, tall nor wide..

Only caveat would be if the stoker stem is long enough to put her bars entirely behind you. Perhaps that is the case?

Pay attention to this posting by uspspro. Your stoker might like 40cm bars, but your legs will probably hit them and make the setup unrideable (and see you are planning on using a 13cm stoker stem, so I don't think the bars will be far enough back to get them out of your way). Like uspspro, we run a 46 cm stoker bar, with an 18cm stoker stem, and I brush her hands with my thighs when she is on the outside of the bars.

Pay attention to this posting by uspspro. Your stoker might like 40cm bars, but your legs will probably hit them and make the setup unrideable (and see you are planning on using a 13cm stoker stem, so I don't think the bars will be far enough back to get them out of your way). Like uspspro, we run a 46 cm stoker bar, with an 18cm stoker stem, and I brush her hands with my thighs when she is on the outside of the bars.

We use a 44cm stoker bar and a 18cm stoker stem with a good upslope so effective length is less. Originally this put her bars right behind the top of my saddle with just enough room for her to grip the bars. Since that time have have migrated to about 15-20mm less seat setback and now she has more room. I am 5'9" and 150 lbs.

There does need to be enough room for the stoker to grip the hoods so she will need clearance for thumbs between her bars and your hips so measure carefully. On the other hand if you measured carefully and 40cm fits then great.

Did you consider S&S with Ti middle tubes and decided against it due to the cost?

Wayne

Pay attention to this posting by uspspro. Your stoker might like 40cm bars, but your legs will probably hit them and make the setup unrideable (and see you are planning on using a 13cm stoker stem, so I don't think the bars will be far enough back to get them out of your way). Like uspspro, we run a 46 cm stoker bar, with an 18cm stoker stem, and I brush her hands with my thighs when she is on the outside of the bars.

Hmm, I thought I had answered this twice before, but obviously I need to do better with my explanations since it keeps coming up. Our current tandem has 38cm stoker drop bars mounted with a 110mm stem. My stoker dislikes the shape/feel of the cane creek dummy levers, so I made a set of round stoker pegs. With this setup, my leg will occasionally brush the stokers hands. With the new tandem we are using a 130mm stem which will give more clearance. However, the bars will be higher up than on the Cannondale. This will again bring the bars closer to my abnormally narrow hips (33cm out to out). If this does prove to be a problem, changing the stoker bar and/or stem will be very easy. Hope this clarifies things! :)

We have a 14cm stoker stem and 40cm stoker setup and it works fine. I have minimal brushup and it is not a problem at all. She did have a 38cm width and that proved troublesome. We ended up putting the 38cm on her single bikes and 40cm on tandem. It all worked out just like it will for rhino919.

Did you consider S&S with Ti middle tubes and decided against it due to the cost?

At $1,300 to $2,500 to add them, S&S couplers wouldn't have fit in the budget. However, if there was no additional cost for the S&S, I would still choose the English method, as I think it is a more elegant solution.
1) It allows for easily changing to different tube materials or thicknesses, although you could argue that a correctly designed frame shouldn't need this option.
2) It eliminates the eccentric BB. To tension the timing chain you clamp the top tube and one end of the boom tube in place, push down on the seat to tension the chain, and clamp the other end of the boom tube.

I do see some potential issues that may not make it suitable for everybody.
1) The clamp bolts must be torqued correctly to make sure the tubes don't slide while riding.
2) The tension of the chain will vary depending on how hard you push down on the seat.
3) The length of the bike could vary a little (+/- 1mm?) from assembly to assembly which would require adjustments to the derailleurs.

At this point, I'm perfectly happy to deal with these issues. Once I actually get the bike, my opinion may change.

At $1,300 to $2,500 to add them, S&S couplers wouldn't have fit in the budget. However, if there was no additional cost for the S&S, I would still choose the English method, as I think it is a more elegant solution.
1) It allows for easily changing to different tube materials or thicknesses, although you could argue that a correctly designed frame shouldn't need this option.


The ability to substitute tubes of different characteristics is very appealing. I now ride a tandem that is the result of some less elegant experimentation along that line. Given the many factors involved, including personal preference, it seems unlikely to me that even a very talented builder can somehow design a perfect frame for a team on the first attempt. I believe we have arrived at a good fit for us but your tandem will allow for much more tuning of the frame limited only to your pocket book and patience.

Wayne

Please keep us updated - I think this sounds like a really cool build, and I like the idea that you could swap the pipes to improve stiffness or ride. Re-setting the RD tension is no big deal, since you'd have the allen keys out anyway to rebuild the bike after flying or similar.

"You can see pictures of the tube in socket method applied to a recumbent tandem here (http://www.englishcycles.com/custombikes/custom-tandem-recumbent/). Bike Friday (http://www.bikefriday.com/bicycles/tandem)also uses this design on their tandems."

To be pedantic, while English is his own project, in effect he's also a major part of Bike Friday. I.E. I'd say that he's using the bikefriday design, not the other way around.

Ask your builder to check the boom tube length relative to where the front bottom bracket spindle will fall in the eccentric once the sync chain is installed.

I believe he may want to add or subtract about 1/2 and inch from that 31" C-T-C spec so your spindle will fall more in the middle vs. being biased well forward or well back of center.

If he keeps it at 31", you can adjust it back to center with a half-link in your sync chain, or you can bias your saddle fore-aft to adjust set-back and then establish your stem length for reach once you've got your set-back squared away.

This is why you'll find that most production tandems use the 1/2" spec on their boom tubes, e.g., 28.5" for Co-Motion, 27.5" for Santana, 28.6" for Cannondale, etc...

That's actually a very important point, something I'd have never thought of when I had mine built. (Thanks TG and others for your tips in that regard on my build thread).


Ask your builder to check the boom tube length relative to where the front bottom bracket spindle will fall in the eccentric once the sync chain is installed.

I believe he may want to add or subtract about 1/2 and inch from that 31" C-T-C spec so your spindle will fall more in the middle vs. being biased well forward or well back of center.

If he keeps it at 31", you can adjust it back to center with a half-link in your sync chain, or you can bias your saddle fore-aft to adjust set-back and then establish your stem length for reach once you've got your set-back squared away.

This is why you'll find that most production tandems use the 1/2" spec on their boom tubes, e.g., 28.5" for Co-Motion, 27.5" for Santana, 28.6" for Cannondale, etc...

Ask your builder to check the boom tube length relative to where the front bottom bracket spindle will fall in the eccentric once the sync chain is installed.

Hi TG,

First let me say thanks for all that you have written about tandems. I've read lots both here on BF and on your blog.

With this design there is no eccentric BB. The tension in the timing chain is set by clamping the top tube in place, clamping one end of the boom tube, pressing down on the seat to tension the chain, and clamping the other end of the timing chain.

"You can see pictures of the tube in socket method applied to a recumbent tandem here (http://www.englishcycles.com/custombikes/custom-tandem-recumbent/). Bike Friday (http://www.bikefriday.com/bicycles/tandem)also uses this design on their tandems."

To be pedantic, while English is his own project, in effect he's also a major part of Bike Friday. I.E. I'd say that he's using the bikefriday design, not the other way around.

You are correct. I should have worded my post differently.

With this design there is no eccentric BB.

Guess I should have read with a more critical eye. I will be interested to hear how this works out.

Had no idea English was involved with Bike Friday.

I can remember getting passed one day in Central Park by a guy on a Bike Friday travel bike. The guy was flying, and the bike was really somethin' else. High zoot, tricked out, etc. Pretty darned cool machines.

I'm really interested in seeing how this all comes together. English def. thinks far outside the box with some of his designs.


"You can see pictures of the tube in socket method applied to a recumbent tandem here (http://www.englishcycles.com/custombikes/custom-tandem-recumbent/). Bike Friday (http://www.bikefriday.com/bicycles/tandem)also uses this design on their tandems."

To be pedantic, while English is his own project, in effect he's also a major part of Bike Friday. I.E. I'd say that he's using the bikefriday design, not the other way around.

Having thought about your design a little more, and in light of the question regarding shifting performance in your original post, the only thing that comes immediately to mind is that you'll need to adjust your derailleurs after you've pre-loaded your sync chain vis-a-via the slip fitting of the boom tube into the socket clamps since the length of your tandem's mid-span will be somewhat 'variable'. In this regard, the new wireless shfting from Campy and Shimano would be a beautiful thing for this one-off design.

Again, I eagerly await its completion, photos and your ride reports.

Here's a photo of an English's recumbent tandem. That took some serious thinking for a one-off. Wow.

http://www.englishcycles.com/custombikes/custom-tandem-recumbent/#

http://www.englishcycles.com/wp-content/uploads/2011/07/tandemtina2.jpg

... the only thing that comes immediately to mind is that you'll need to adjust your derailleurs after you've pre-loaded your sync chain vis-a-via the slip fitting of the boom tube into the socket clamps since the length of your tandem's mid-span will be somewhat 'variable'.

Rob says that with a little practice you can get it so the mid-span doesn't vary from assembly to assembly. However, I expect to have to make a minor tweak to the derailleurs after each assembly.


In this regard, the new wireless shfting from Campy and Shimano would be a beautiful thing for this one-off design.

I totally agree! I'm hopeful that one of the two will eventually produce a triple FD, but don't expect it for a couple more years. I figure that Shimano will be working on Di2 for mountain bikes next. Hopefully that will push them to develop a triple FD.


Again, I eagerly await its completion, photos and your ride reports.

Me too!!!

I wanted to apologize if that came off as sharp / snippy, I was trying to go for clarification per-se.

I live in Portland, and due to geographic realities, there are a number of Bike Friday's on the road. I would find myself being passed by a mom riding a triplet & tag-along (so 3 kids) for a few years while commuting to and from work. Finally, just because it always tickled my fancy whenever I saw it, a former mayor (Bud Clark) would often be seen riding his bikefriday around town.