Quentin has a growing family that loves to ride bikes together – particularly tandems. But what to do when your stoker is already taller than her mum? Time to get in touch with those friendly folks at Waltly for a custom tandem frame of course!
We’ve already seen a tandem from Waltly earlier in the year so it was interesting to see how Quentin went about his project…
I’ve been following Waltly for a few years as I’ve considered our options when upgrading tandems. During the last few months Waltly have re-done their web site so it looks very professional, including a nice form to fill out for requesting a quote.
Having done so I received a response the same day from Amy. Her English is pretty good, and she generally responded to my emails quickly given the 13 hour time difference. I sent her a picture of a frame with similar geometry and specified all of the key dimensions. Waltly’s process is to quote a price, and then to ask for 50% of the cost to be paid up front before producing detailed drawings.
All good so far, it sounds like you had a few interesting details in mind too?
Yes! The Boost through axle standard. This means 148mm x 12mm rear and 110mm x 15mm front axles. This is a mountain bike standard that is relatively new, but I think makes a lot of sense for tandems, especially the wider front wheel (rear hubs wider than 148 have been used on tandems before). I did this because I want durable wheels and because hopefully it will increase the availability of stock wheel options in the future.
The second thing I wanted to do was replicate the geometry of my wife, Heather’s, road bike on the front end of the tandem. And also to eliminate the toe overlap that her road bike suffers from as it can be a hazard on a tandem!
Both of these choices led to me asking Waltly to make a custom fork to go with the frame because no stock carbon tandem forks currently offer the Boost spacing, and because I needed a higher than usual fork offset.
Eventually I settled on a 71 degree head tube angle. While this may make the handling a little more sluggish, it is frequently done on smaller frames, including Cannondale’s smallest road tandem. With the slacker head tube it is possible to extend the fork offset to 55 mm while still having a reasonable amount of trail.
Nice, I like the technical details of getting things to fit, especially given the restrictions around making frames for smaller riders. The other traditional option for smaller frames has been smaller wheels which could always be an option. Speaking of which…
I asked Waltly to allow for 700C wheels with either 30mm wide road, or 40mm wide gravel, tyres. The distance between front and rear bottom brackets also required careful thought. First, I want the option of a Gates belt drive in the future, and second I want the spacing as far apart as possible to accommodate taller stokers, so I chose the largest spacing that will support a Gates drive.
Phew, with the design in mind the hard work starts; sweating the details!
After making my initial specifications and paying the deposit, we went through several iterations of drawings before I decided they were ready. Much of this had to do with trying to fix the toe overlap issue. Now that I’ve done this I realise I could probably have used something like Bike CAD to figure that out beforehand and get through the process much faster, but Amy was patient and responsive with my continual tweaks.
In addition to the frame and fork, I asked for an adjustable stoker stem.
About 6 weeks after I approved the drawings, Amy sent me an email with a set of detailed photos of the finished product. When I gave my approval based on the photos, the frame, fork and stem were shipped by DHL, and arrived in the US just 3 days later.
Now for the exciting part! But you had a small issue with the order I believe?
The build quality of the frame looked great, with neat welding too. As I got started on the build I discovered that Waltly had made a mistake on the stoker stem, building it for a 28.6 mm diameter seatpost rather than the 31.6 mm diameter I had specified. I sent Amy a photo and she agreed that they had made a mistake. They created a new stem as I had specified and sent it to me at no charge. I commend Waltly for their responsiveness in fixing their error.
I’ve noticed some nice finishing touches there…
Before completing the build, I added some yellow and green paint using stencils. I love the look of titanium, but wanted to add a little more colour to go with the yellow and green trim I was adding to the bike. I think this is a great solution for customising a titanium frame that’s relatively easy to do and still allows the titanium colour to show through. The saddles don’t match the rest of the scheme as well because they happened to be preferred saddles from previous bikes.
Nice work there, and some good detailing on the components too!
I built the bike up using a SRAM Rival drivetrain with mechanical disc brakes so that I could add bar-top auxiliary brake levers. I used 203mm discs front and rear for maximum braking power. Waltly only had post mounts available for 160mm rear rotors, so I used an adapter on the rear brake. The fork had IS mounts.
We wanted a good low gear range so I used 46/30 chainrings with an 11-32 cassette. This is not something SRAM designed their 2×11 road groups for, and I found I had some difficulty getting the front derailleur to stop overshifting and dropping the chain to the outside. The Sugino cranks are designed as a triple, so I installed a chain guard in the position of the outer chainring, and it seems to have solved the problem for now.
The one mistake I made in my design was forgetting to specify a front derailleur mount, which was my original intention. There are many clamp-on front derailleurs available, so it wasn’t a big deal, except for the fact that the location of the water bottle mounts on the rear seat tube have limited the range of movement available to me for vertical placement of the front derailleur. So far I have been able to get things working. If I were to do it again, I would want either a derailleur mount with a wide vertical range, or put the bottle cage bosses in a different location.
A good point there. I normally caution against front derailleur mounts because of the wide variety of front mech/chainring combos that you might find yourself outside of. Quentin also raises the excellent point of thinking how the water bottle mounts are going to affect things too.
Even with the Kenda Happy Medium 700x40C tires, there is plenty of clearance. I tried inserting a mountain bike wheel in the frame with 27.5×2.1 tires and they appear to fit, so that will be an option we consider in the future for riding gravel roads.
Excellent work there!
Another excellent build there and one with some fine attention to finishing details. I love Quentin’s stencil work on the frame and the colour matched components. You can’t deny that he’s hit his goal of putting together a family tandem that his wife and daughter should love riding.
Perhaps the only thing that does raise a question for me would be the construction of the fork. I’d like to have made that tubing as large a diameter, and with as thick a wall, as I could. Quentin says he went with Waltly’s suggestion for the design but I’d be interested in seeing how it handles and if it flexes under heavy braking. The other alternative, of course, would have been opting for a ‘squid’ or truss design instead.
Given the issues Quentin was describing with avoiding toe overlap earlier I think I’d have been tempted to build the bike around 27.5″/650b wheels to start with. You’re perhaps sacrificing some rollover comfort for a stronger, lighter wheel with less clearance problems. It looks like you should still be able to find a decent range of road/gravel tyres too. Just don’t forget to raise that bottom bracket slightly to keep the pedals clear of the floor!
Another day, another fine bike for us to admire. Here in the UK at the moment it’s getting pretty blooming cold and we’re seeing quite a bit of snow around. Which means it can’t be that long until we hear the jingle of Santa’s sleigh approaching. Fingers crossed we’ve all been good enough boys and girls that he’s going to bring us all some fine bicycle related presents…
In the meantime – Merry Christmas and a Happy New Year! I do hope you enjoy reading the blog (well done for making it this far down the page!) and I can guarantee you that we’re going to have something pretty special arriving in 2018 😉
If you’d like to read Quentin’s original blog post about his bike, it’s over here: