Tikit conversion to internal hub gear

I've always thought that the Bike Friday Tikit should have an internal hub gear.  The range with the derailleur is less than most 7sp and 8sp hub gears and the hub gear is cleaner and better protected from the environment, all good things on a commute oriented folder.  I expect that Bike Friday released it with a derailleur because the hub gear would have added a couple of hundred dollars to the cost.

Yesterday I built a Tikit rear wheel with a SRAM S7 hub.  It was probably the most annoying wheel that I've ever built...there are 36 very short spokes (around 6" each) in a tiny little rim.  A Park spoke wrench just fit between each of the spokes.  It was very comforting to finish it.  I chose the SRAM S7 over the Shimano Nexus 8 for a few reasons:

  • A LBS (Aaron's Bike Repair) stocks the SRAM S7 and spare parts.  I've overhauled SRAM S7 hubs before and they are pretty easy to dismantle and put back together.  I probably won't need to, but it is nice to know that I can.
  • The Nexus 8 is pretty hard to find right now (specifically the shifter is hard to find right now).
  • The SRAM S7 has a similar gear range to the Nexus 8sp.
  • I prefer the clickbox to the shifter cable arrangement on the Shimano Nexus hubs.

This morning I put the rest of the bike together:

The hub gear makes the bike look a lot cleaner.  There is no derailleur hanging down low to pick up dirt and road grime.  You might ask how I got away without a chain tensioner since the Tikit has vertical dropouts.  The answer is that I was lucky -- the stock 53t chainring and the SRAM 18t cog work perfectly with the chainstay length on this Tikit.  They also give good gearing: 27", 32", 38", 47", 58", 70", 82".  I'd like something in the 60s between the 58 and 70, but this is good enough and the range is exactly what I wanted.

I bought the drum brake version of the hub and removed the stock V-brake.  The drum brake should work well in this application and will allow the rim to last nearly forever.

I wanted to experiment with some other flat bars, so I ordered a pair of "Origin-8 Space Bars".  They are sort of a hybrid between Moustache bars and Albatross bars, hopefully it is a combo that works well for me.  The make the folded bike smaller than drop bars and work more easily with the hub's rotary shifter.  They also have some rise, so I'll probably need to cut down the stem mast a little bit.

The bike folds to about the same size as the stock Tikit:

I spent all day working on projects, so I didn't get to give the new setup much of a test ride (just a few laps around the block).  I'll report back on how the bike works in this configuration.  I think it'll work very well. 

Published 29 October 2007 04:38 AM by AlexWetmore

Comments

# Phil R. said on 30 October, 2007 07:33 PM

Do you have a link to the Origen 8 space bar.   Where do you buy them.  They look like the On one Mary bars.

# Mike Jenkins said on 31 October, 2007 09:25 AM

What size rim did you use and where did you find it?

# Larry Leveen said on 02 November, 2007 10:21 AM

I have been using the Origin 8 Space Bar on my MTB and have enjoyed it, though I suspect I'd be even happier with a drop bar -- hand position is about half-way between a flat bar and a brake hood, IMO. A drop bar would bring up other issues like switching to road version BB7 disc brakes and where to mount the SRAM trigger shifter for my 1x9 setup (answer: go Rohloff!).

BTW, that closeup of the hub made me do a double-take. It looks a bit like the spoke just right of the valve is attached to the drum brake actuator arm, but I see the real cable now. What's that loop-looking shape just over the actuator arm?

# christian said on 02 November, 2007 10:59 AM

Oh,  that's nice to see put together.  Is that a size large? if so , I'll file away that information about the magical lucky chainring/cog combo for future use.

Does the reaction arm thing on the hub brake make wheel removal more difficult, or is there some kind of quick release like the ones Rohloff uses?

# AlexWetmore said on 02 November, 2007 04:58 PM

Phil -- Origin-8 bars are available from most bike shops through J&B (a distributor that bike shops order from).  Origin-8 seems to be cloning many of the On One bars at cheaper prices and they are easier to get.  This one costs about $30.

Mike -- It is a Sun M14A in 349mm and 36 holes.  It cost about $40 and my LBS ordered it through J&B.

Larry -- The loop is just the end of the brake cable.  The cable clamp seems to want you to route the cable back on itself.  I didn't want a hard crimp, so I left an open loop.

Your issues for switching to a drop bar are similar to my issues for switching to a drop bar, so I'm trying this as a compromise.

Christian -- This is a size large Tikit.  The reaction arm does make rear wheel removal more difficult, I'd need to loosen the bolt and clamp.  I might make a different clamp that makes it QR.

# Vik said on 13 November, 2007 04:35 PM

Since the Tikit has vertical drop outs will you have issues as the chain stretches since you can't adjust the hub?

# AlexWetmore said on 14 November, 2007 02:35 PM

We'll see.  If I do have problems then I'll use a chainstay mounted tensioner (there isn't much space for a dropout mounted one due to the clickbox).

In my experience chains on internal hub gears last a very long time without noticable stretch.  If I get a couple of thousand miles without needing to adjust it then I'd happily move the chain onto another bicycle and put a fresh chain on this one.

# Jean-Yves said on 20 January, 2008 01:48 PM

Hello,

sorry for my english, but I am french ! I would like to buy a Tikit because I find this bike great, but I am afraid with the cable. I know that Bike Friday has made some modifications to improve the bike. Do you think the flexing problem is solved ? Is the stem stiffer now ? Do you have problems with your tikit ? I would like in fact to buy the express Tikit :  do you think that with the cable it is ok, or may be it is better to buy this bike with the stem knob ?

I would prefer with cable but I need some advice.

Thanks for your response,

JY

# AlexWetmore said on 20 January, 2008 09:51 PM

I think that the cable problems are solved.  I retrofit my tikit with the new system and it provides for a more rigid stem.  The new cable is very large (about 4 or 5mm in diameter) and strong and also easier to adjust.

The main reason to get a model T tikit would be cost savings.

# Kai Fuchs said on 19 February, 2008 11:55 AM
Hello from good old Europe, I^m building since a few months the tikit optional with the Nexus/Alfine internal gearhub, but with tensioner. I prefer the Shimano version instead of the SRAM 7 speed version because the gearbox at the SRAM hub doesn^t really last long on such a bike. Without a tool not so easy to replace when broken. You have luck with the 53/18 combination, but if the chain gets longer, you`ll get a problem. Here is the solution for you: http://trickstuff.de/index.php?p=d110de1 This is an excentric bottom bracket from Germany for standard BSA bottom bracket shells in combination with Hollowtech 2 cranks. Invented for Single speed, but usefull for internal hubs too. It shorten the chain by 6 mm. Best regards Kai Fuchs Bike Friday Europe
# AlexWetmore said on 19 February, 2008 08:16 PM

The SRAM 7sp clickbox is well protected by the heavy gauge wire which wraps around it.  This is my third bike with this shifting system (one of the others was a folder) and I've never had a problem.  I find it easier to remove the clickbox than to undo the cable on the Shimano system.  The big wins with the SRAM are that it has a wider gear range than the Nexus 7sp, more even gearing than the Nexus 8sp, is more efficient, more robust, and comes with a nicer drum brake.

Please link to photos when you've done a conversion, I look forward to seeing it.

I learned about that eccentric bottom bracket from another friend recently.  Something to check out if I have chain wear issues.  So far it's doing fine -- if I get 1500 miles out of a $10 chain before it stretches too long for this bike then I'll be very satisified.