high speed geared Coker


Just got back from my first ride on a Coker built up with a Greg Harper geared hub (1.5 to 1 gear ratio). It is AWESOME- like Blue Shift on steroids.

Max speeds on a regular Coker can be done with ease on this thing.

Quite possibly this may change the face of Coker touring, in terms of how far you can go in a day.

Harper is in town and we’re all going to go out and try it later today- we’ll post again when we get back.

Kris Holm.

:astonished: Blue Streak? Blue Death? At least Blue Abrasion. :astonished:

Wow! You must’ve been flying! I assume you had brakes. How was the acceleration? Also, do you plan on connecting a cyclometer and getting some numbers? I imagine the falls must be nasty. Have fun! Also, how’s mounting the thing? I imagine it’s a bit harder than your average coker.

time to start a dead pool.

Racing stripe? (as in - a little frightening…) :frowning:

Somebody should shave the nubbins off that thing and take it to a velodrome for a speed record. At those speeds the banking begins to make sense. Would look great in a video, and speaking from experience, the world-warping nature of high-speed track riding is a hell of a weird rush.

Hey Kris:

I remember you telling me about that geared Coker when we rode in Venice, and I remember telling you I wantd one soon as they were available. I welcome any and all stories about your high speed experiences, and any info about getting one of those hubs.

Take care,
John Long

too bad i was busy today, i would have liked to have come to that meet but i don’t think i would have been able to mount it. i can barely ride a regular coker.

That’s fantastic, I was wondering when somebody would do that. :slight_smile: What length cranks were you using? As Bevan mentioned, it would be really great to see some top speed data, etc. That, and videos.


What are average/max speeds on a regular, 1:1 Coker?

Depends on the person riding. For most riders with the stock 6 inch cranks a comfortable cruising speed on a flat trail would be about 12 mph to 13 mph. Average speeds are going to be less just because you don’t push the speed the whole ride and you’re not always riding on a flat smooth trail. An average speed of 10 mph for a ride would be more typical.

There are people who take their Coker riding seriously and they can go faster. A good rider with shorter cranks can go faster and average a higher speed.

Max speeds on a Coker have been reported to be 20+ mph. But you have to be a super good sprinter to do that. That’s over 200 revolutions per minute.

My max speed is 17.5 mph and I’m not going to do that again. Once you get over 13 mph you’re going fast enough that you will not be able to run out a UPD. Speeds over 13 mph are where I get nervous about what would happen if I had a UPD.

A geared up Coker is not going to be as easy to ride as people expect. I’ve ridden Blue Shift it’s a temperamental unicycle. When it’s geared up your balance envelope shrinks. Your ability to correct your forwards and backwards balance is less.

On a flat and smooth bike trail the Blue Shift is an absolute gas to ride. It’s fantastic. However, if there are any irregularities in the trail (bumps, dips, rough pavement, etc.) then it gets to be quite a bit more difficult to control. For example, when crossing intersections there can be dips in the pavement where the cars have worn ruts in the road. Riding across those ruts is difficult. I had several UPDs just crossing intersections because of that. Riding up sidewalk cutouts (the wheelchair cutouts) is also difficult on Blue Shift.

Climbing with the Blue Shift is also more difficult because of the smaller balance envelope. You can’t lean out in front of the unicycle as much because the balance envelope isn’t big enough. It is difficult to keep your balance while climbing. Even slight climbs present a challenge. The challenge isn’t in having enough leg power to make the climb, the challenge is in maintaining your balance.

There is also something else that is odd about the Blue Shift but I can’t identify what it is. There is some slop in the gears which creates an odd feeling. But I also get the sense that the torque arm is putting some force on the frame and pushing the frame forward. I don’t know. There is just something weird in the feel of the unicycle that makes it very temperamental to control.

Blue Shift is a blast to ride on a flat smooth trail. Add in some hills and rough pavement and it gets to be quite a challenge.

It will be interesting to see Kris’ opinions about the ride of the geared up Coker. Kris is a very good rider so the smaller balance envelope may not make much of a difference to him.


Is there any chance that the smaller balance envelope is due to the lack of experience with Blue Shift? Does Greg report the same impression? Do you think the issue of the decreased balance envelope will minimize itself over time with practice- a little or a lot?

Just Curious.

Greg Harper reports a similar opinion. But he’s less willing to call his unicycle temperamental in public. :slight_smile:

With more practice you’ll get more used to the smaller balance envelope. I only spent a couple of days on Blue Shift so more practice would help. But that still doesn’t change the fact that it’s a more difficult unicycle to ride than an equivalent big wheel unicycle with a 1:1 gear.

On a Coker you can daydream and zone out while you ride. You cannot do that on Blue Shift. On Blue Shift you have to keep your concentration or it will dump you.

I can see the geared up Coker being a good unicycle for speed records and having fun with. But I don’t think it will turn out to be a good unicycle for long rides because as soon as you get tired, or as soon as you stop concentrating, it will dump you.

When the commercial versions of the geared hub become available I’m going to put one on my need to get list. It’s just a fun ride. I’d probably go with a geared up 29er rather than a geared up Coker. I don’t have a need for that much speed. A geared up 29er is a blast to ride on the right trail. A definite need to get unicycle.

Oh boy :astonished:

I want one!

Just a few Q’s: How does the backlash affect your pedalling speed? Are you using longer cranks to compensate? What is your top speed and average Coker speeds on the flat? How different is that with the geared up Coker? What about hillclimbs and downhills? Did you take it off road?

Look forward to your ride report Kris!


p/s Did I mention I want one? :stuck_out_tongue: When will the Harper hub be available?

John, I want a geared up 29’er too- I think it will be the perfect travel unicycle. Easy to take on a plane and then Unitouring in 1:1.5 mode. Flick it to 1:1 mode and you have a MUni to ride on your trip! As for the geared up Coker- that would be perfect for the UNICON 10km road race.

So a blueshift won’t be a 24hour race machine? Once you inevitably get groggy and tired you go down? I guess that’s not good for long endurance races. Do you think that anyone can get good enough on a blueshifted uni to be able to zone out on it? Would you akin riding blueshift to an easier version of gliding-If you’ve got your concentration on it it’s perfectly easy (once you’ve learned it), but if you let your mind wander you lose it and fall?

I wouldn’t say that no one is going to get good enough to ride Blue Shift or a geared up Coker on long rides. In fact, I’m sure there are some riders who are good enough that they could take Blue Shift or a geared up Coker on long rides. I just don’t expect normal riders to ride them with a lot of control and a lot of speed. They’re going to be challenging to ride.

I don’t think anyone will be able to zone out to the degree that you can on a Coker or a standard unicycle. The geared unicycle is just too twitchy. But good riders could probably zone out a bit.

With a geared up Coker I think the current 100 mile record of 6 hours 44 minutes will be in jeopardy.

So this hub Kris is riding is not that same as Blue Shift? What is the gear ratio on Blue Shift? Can you still go backwards (I know there’s no real need to, but just out of interest!) and idle etc?

blueshift is geared up 1.5:1 and it does go forward and backwards. the hub in the coker is the same one i believe
check out harper.unicyclist.com

Kris has one of Harper’s hubs. I assume that’s the one he’s using on his geared up Coker.

The Blue Shift has a 1:1.5 gear ratio. One turn of the pedals gives you 1.5 turns of the wheel.

You can still ride backwards and attempt to idle when it’s geared up and when it’s put in the 1:1 gear ratio.

The Blue Shift is shiftable. Meaning that you can put it in 1:1 gear or the geared up 1:1.5 gear. You have to stop and dismount to change the gear. You cannot shift while moving.

There is more information about the hub and Blue Shift here:

Look at “Blue Shift” and “Epicyclic Hub project”