Model B problems

mcb0sse · Post by **mcb0sse** » March 6th, 2007, 12:06 am

Hey everyone,
I've been refitting my model b for the last year or so now, and have come across a problem. I just replaced the chain and s.c.a.m, and now the chain seems to skip a gear on the fan. It has always skipped on the smaller of the two gears, but now it is beginning to skip on the larger one. I can pull around a 2:00 split without it skipping, but if I row any pieces at a lower split, it will skip. So my question is: how durable are the gears on the fan?, and are they replacable?

Thanks for the responses in advance.

Alex

mcb0sse · Post by **mcb0sse** » March 6th, 2007, 12:08 am

I just did some research, and found that I can replace the sprocket. What are the chances it is this?

johnlvs2run · Post by **johnlvs2run** » March 6th, 2007, 12:44 am

That's probably around 100 percent what the problem is.

I replaced the 13 tooth cogwheel with a 14 tooth on my model B, which gave me the same resistances vs drag factor as the models C-E. I'd recommend doing the same. Also, changing and using this cogwheel will give you a straighter drive than if you used the 15 tooth cogwheel.

This part is inexpensive, and it will take about an hour to change it.

PaulS · Post by **PaulS** » March 6th, 2007, 10:40 am

C2 generally recommends replacing the cog at the same time as the chain for that stated reason. Also order up a speed ring for the B as it will help to get the DF a bit lower, especially if you decide to go with a lower tooth count cog. And always make sure the chain is lubed well, the only instance I've ever had of skipping, was fixed immediately with an oiling of the chain. May as well give it a first try to see if it works for you too.

mcb0sse · Post by **mcb0sse** » March 8th, 2007, 4:14 pm

Thanks guys, I called concept2 and bought the cog pieces. Twenty dollars for the parts, so not terribly expensive. Are there any other things I should/could get to upgrade the erg? I feel as though concept2 should start producing different types of ergs...like the class D sport, or class E special edition...

Thanks again,
Alex

PaulS · Post by **PaulS** » March 8th, 2007, 4:55 pm

mcb0sse wrote:Thanks guys, I called concept2 and bought the cog pieces. Twenty dollars for the parts, so not terribly expensive. Are there any other things I should/could get to upgrade the erg? I feel as though concept2 should start producing different types of ergs...like the class D sport, or class E special edition...

Thanks again,
Alex

A current model of the PM would be good, along with the "Speed Ring" already suggested. (not sure it was clear)

Perhaps you are being humorous, but this is the first time in the history of C2 that more than a single model option is being offered as standard, and there are 3; The D, The D/PM4, and the E. Of course they all do exactly the same thing for the most part.

johnlvs2run · Post by **johnlvs2run** » March 8th, 2007, 5:13 pm

What pm are you using?

A speed ring is very helpful, to get the full range of resistances.

You can order one from C2, or easily make one from black roofing paper and use plastic ties to attach it to the fan side of the erg.

c2jonw · Post by **c2jonw** » March 11th, 2007, 11:40 am

Last time I checked we no longer were selling the B speed Ring, but any means of blocking air flow on either the inlet side (damper) or outlet side (circumferential) will lower the drag factor. Roofing paper, duct tape, cardboard or positioning the machine tight to a wall will work. Just be sure that whatever you use will not get sucked into or blown out of the fan cage. Once you have a method it's just a matter of fine tuning how much blocking feels good to you and achieves the desired drag factor. C2JonW

mcb0sse · Post by **mcb0sse** » March 11th, 2007, 11:52 pm

While we're on the subject, how accurate is the pm1 monitor with measuring split? I sometimes think that mine isnt quite that accurate.

johnlvs2run · Post by **johnlvs2run** » March 12th, 2007, 12:17 am

The watts are reasonably accurate, but the conversion to pace is erratic. I found the pace to be 1 to 3 seconds slow at a 2:00 pace and this varied considerably.

Also the pm1 rounds up the pace, instead of taking the average. For example if you consistenly do 1:58.1, the monitor will average that out as 1:59.0. Add to this the variable 1 to 3 seconds it is off.

If you row by the watts and then calculate the watts to pace by formula, you should get an accurate pace. Then you can compare this with the shown pace and see how far it was off. However it is much easier to just get a pm2 monitor.

PaulS · Post by **PaulS** » March 12th, 2007, 12:34 pm

mcb0sse wrote:While we're on the subject, how accurate is the pm1 monitor with measuring split? I sometimes think that mine isnt quite that accurate.

As John mentions, the Way it calculates Watts is well enough, though the conversion from watts to Pace was done from a precalculated table that introduced some errors.

At a 1:55 pace, you are on par with the other PM's
At any pace slower than 1:55 the watts required for a given pace gets increasingly higher than the other PM's.
At any pace faster than 1:55 the watts required for a given pace gets increasingly lower than the other PM's.

The variance is non-linear.

The displayed pace is actually not rounded at all on the PM1 but truncated, so a 1:55.9 is displayed as 1:55, making it possible to pull nothing but 1:55's and still end up with a 1:55.9 500m time. On the Current PM's if you pulled nothing but 1:55's for 500m, the maximum possible time would be 1:55.4 as they follow regular rounding rules.

A mod B can be upgraded to a PM2 or above. I'm nto sure if C2 has any more PM2's but there may be a secondary market for them from people upgrading to the PM3 or above. You will still require the mounting hardware from C2 (or home make something), that is about $15 IIRC.