shock cord replacement

[cityeast]

I just replaced the first shock cord in my model D, after around 1.3 million metres, as it was quite frayed, but not to the extent of making the core visible. I was starting also to notice fray fibres when oiling the chain, so I knew it was time to change. I was also experiencing greater than usual fluctuations in my pace times on the PM3 for each stroke than I considered to be correct.

IMHO the C2 documentation on shock cord maintenance is vague. C2, if you are listening, please revise the PDF, to include step for step diagrams for adjustment AND replacement. For example, it is not mentioned that removing the black cap at the flywheel end of the chain housing helps facilitate the replacement of the shock cord.

Having said that, its a pretty straight forward job and requires only an hex-key tool to remove and replace the black cap. All in all and easy 15-30 minute job.

The interesting thing was that my pace times flattened out, indicating that the worn shock cord, or the whatever was causing it to wear, was interfering directly or indirectly with the PM3 reading.

[johnlvs2run]

That is interesting, as my old shock cord with a pm2+ made no difference to my times, except the new one had more resistance on the drive so I think the old one was faster.

I had about 20 million meters on my model B and the handle was getting about 6 inches from the cage. I'd not known firming it up was a simple 2 minute adjustment, discovered and did this adjustment, then ordered a new shock cord and changed it. The old shock cord was somewhat frayed but still good.

I readjusted the new cord, making it as long as possible, but it still had a lot more resistance than the old one, which I feel makes the same times harder to accomplish. However, regardless the old cord or the new one, the times were consistent on the pm2+ monitor.

[jahink67]

John is the shock cord really easy to adjust or replace. I just bought a B model from a lady here in town and it is a little worn. track needs cleaning and shock cord could stand to be adjusted or replaced.

Thanks
John

[johnlvs2run]

Hi John,

Yes the shock cord is very easy to adjust. The first time only took me a couple of minutes. All you do is pull out the clip from the back of the railing, snug up the cord a bit, and put the clip back in as it was. The handle on mine was hanging about 6 inches from the cage by the time I figured out how easy this was to adjust.

Replacing the cord takes more doing as you'd need to take out the inside of the railing. Personally I wouldn't replace the cord unless it shows danger of coming apart. Some fraying is normal. The thing is a worn shock cord functions much better, and new ones have a lot of resistance.