Twombolt info and instructions

Twombolt Instruction Manual
Download the Full Manual (PDF – 762kb)

Our update to the Wombolt crankset is on its way to shops and distributors. Twombolts (Two+Wombolt) are available now in fluorescent red, white and black. We have RHD-175 at the moment, with LHD and other sizes following soon.

The new features for the crank are as follows:
Updated mating arm lug for improved fit and increased durability.
All-new cluster design that optimizes the arm’s interface, simplifies assembly, and makes use of a durable AND replaceable elastic retainer band.
Greatly improved overall function and performance proven both in the lab and during extensive long-term riding.
2 lbs. 2.5 oz. / 978g (with Mid BB). 1 lb. 13.5 oz. / 836g (without BB).

New Twombolt mating arms and wedge clusters are compatible with existing Wombolt drive arms (click to enlarge).


6 place sprocket.jpg

1. Slide the sprocket onto the spindle.

9 lube sprocket bolt.jpg

2. Lubricate the sprocket bolt threads.

10 tighten sproc blt.jpg

3. Start the sprocket bolt in the crank arm threads. Do not fully tighten it down. This step helps to keep the sprocket properly oriented in the following step.

11 sprocket seat.jpg

4. To seat the sprocket, place the spindle in a bench vise and gently tap the crank arm using a hard rubber mallet. Use wood to protect the sprocket. Snug the bolt into place after fully seating the sprocket.

a bb check.jpg

5. Check for the proper bottom bracket spacer tube size by holding the assembly up to the frame’s bottom bracket shell.

b bb lube.jpg

6. Prep the bottom bracket shell with light grease.

c bb press.jpg

7. Use a bottom bracket press to fully seat the bearings. If a press is not a available, a make-shift version can be made by using two plates (old wood, sprockets, bearings, etc.) a bolt, a nut, etc.

d bb spacer visible.jpg

8. Note the fully visible and properly positioned spacer tube in this photo. This spacer tube should always be used.

e sprocket washer install.jpg

9. With a 6mm (1/4″) sprocket and a Mid BB, use one of the thick (3mm) spindle washers to achieve proper chain alignment. Adjust this spacing as necessary to accommodate any variation with the BB and sprocket size.

f crank bb install.jpg

10. Slide the spindle all the way through the bottom bracket bearings. The spindle should slide through with only a very gentle amount of force if the bearings have been fully seated in the frame’s BB and are manufactured to the proper 22mm inner diameter specification.

g sprocket washer vis.jpg

11. Note the thick spindle washer (3mm) between the 6mm sprocket and Mid BB.

i washers loose.jpg

12. Slide the included spindle washers on. The spindle washer diameter allows the crank arm to move past the wedge cluster, so be sure to back the wedges up against at least one of them.

ja washers half way.jpg

13. Use enough washers to cover the spindle’s “step” between round and hexagonal by at least 1mm.

k washers fully seated.jpg

14. Only the spindle’s hexagonal flats should be visible after the washers are installed.

l alum dust option 1.jpg

OPTIONAL: Most aluminum dust covers can be used. However, you should be sure to use at least one of the included spindle washers between the dust cover and the wedge cluster. If there is not enough room for this, stick with using the washers alone.

n install wedge.jpg

15. A gentle amount of force will allow the new elastic cluster band to expand for installation on the spindle.

o push wedge on.jpg

16. Slide the wedge cluster into place.

p lube under wedge.jpg

17. Flip each individual wedge up and apply anti-seize to the spindle’s hex flats.

q lube spindle thread.jpg

18. Lube the spindle threads.

r lube wedge face.jpg

19. Lube the wedge faces that contact the arm.

s smooth wedge face.jpg

20. Smooth the anti-seize over the entire wedging face.

t install arm.jpg

21. Push the crank arm onto the wedges.

u lube arm lug.jpg

22. Use anti-seize on the lip where the locking bolt contacts the crank arm.

v lube threads.jpg

23. Lube the lock bolt threads.

x crank tighten.jpg

24. Tighten the lock bolt as needed with an ordinary “long” 6mm hex key wrench (shown).

y bolt tighten.jpg

25. Check the sprocket bolt tightness.

z crank spin.jpg

26. The cranks should spin freely in the bottom bracket if you’ve done everything properly. For additional tips and information, please check the instruction sheet included with the crankset.