PDA

View Full Version : KH Hub and Cranks on a Coker


muddycycle
2005-07-18, 06:40 AM
In another thread I was wondering what crank size to use on my up coming Coker tour of the San Juan Islands. It was suggested that I take different sizes and change as needed. I was testing that concept out this weekend and had dreadful results. First I strip out the threads on the 110ís I was taking off, one side came off as normal the other took a bearing puller and about an hour of sweat. Next I noticed that threads on the Suza hub were shot, all broken up and falling off when I put on the 140ís I could tell it was going to be a problem. I went for a ride in the hills, at the five mile mark I stop to check the cranks, sure enough the side with the bad threads was loose. I was tightening it when, snap, the bolt broke of the remaining good threads. The crank was tight but the bolt would no longer hold. I continued on over the hill heading back home and almost made it before the crank fell off. So now I thinking great, but good thing it happened here at home before the trip and I have some time and tools to fix it. The hub was worthless so I unlaced the wheel while thinking about what else I should order from Unicycle dot com. I was thinking that it would be easier to change a splined hub while on a road trip, less danger of something going wrong. I have a KH24 with 170ís and a spare set of 140sí for it which I almost never ride any more. Off comes the KH24 wheel, de-lace the hub, lace the hub to the Coker Airfoil with a four cross pattern and presto problem solved. The only tricky part was getting the 12 gauge spokes on to a hub that had holes for a 14 gauge, it just fit by turning the spoke threads into the hole, tight but, I didnít have to drill the holes out ( I may want to put the hub back on the KH). Todays test ride was great I like the 140's for over all riding most hills are no problem and it's not to slow on the flats and I can switch to the 170's for the moutain climb.

jagur
2005-07-18, 08:08 AM
that sounds like fun, i love crazy projects like that. bring it with you tomorrow to the club thing if you can. see you there.

fexnix
2005-07-18, 08:28 AM
ttiwwop

GizmoDuck
2005-07-18, 10:33 AM
If only we had more choice of crank lengths with splined hubs, and some lightweight splined hubs! All the ones out there are overbuilt for trials and only offer a couple of crank lengths. With a Coker, you want to have 100s, 110's, 125s, 150s at the very least, and possibly 170's as well.

Whilst you have heaps more crank length choices with square taper hubs, it spells disaster if you screw up your hub threads. I had to cut my cranks off the UDC hub (after rounding off the crank thread on the Bicycle Euros), only to have a nailbiting moment, when I realised the thread in the hub itself was almost rounded off. Luckily I have just enough thread deep within the hub to hold another crank on there. Rebuilding a Coker wheel take some effort, especially if you have to try and $ave the Tommy Miller spokes. It took my bike mechanic 4hrs to build my wheel, normally takes him 40min to build a regular bike wheel.

Also, your crank is less likely to get stuck to the hub in the middle of nowhere.

If I had to build a Coker Wheel again, it would definitely be with a Splined hub, even with the crank length limitations. The solution might be to get a couple of long 170mm splined cranks and machine a thread to give youself shorter lengths, like 100, 110, 125s and 150. That, or you wait a year or two and hope for a few more splined setups to appear on the market. Sure beats a wheel rebuild.

U-Turn
2005-07-18, 11:23 AM
Although I admire the splined concept from a technical viewpoint, I think that most crank/thread problems with the square taper are due to improper installation/maintenance. I'm working with 20" -> 36"+ every day with a large variety of cranks and haven't yet seen the problems I hear about.

If you hammer on a nail that's upside down it doesn't go in properly and will bend; why should a unicycle hub/crankset be any different?

Excellent swapping around, though, muddy!