I have a EZ-1 sc bent, what would be the largest gear I could use to replace the 52T chainring without changing anything else. I want a little more top end on the flats. thanks Rogermo it an't all that bad
I presume the front der is a clampon type. If so you
could probably go up to a 56T ring with only a little
strain, especially if you didn't use the larger two
cassette rings. Shifting might be a bit marginal but
there are a number of Rans bikes with chainring triples
from 22T on the inside to 60-62T on the large ring.
Larger than 56T would mean a longer chain and increased risk of problems but I have only anecdotal
information in that regard. I just know it has been
done on a lot of bents. Steve
...but I've got an opportunity to get a 32/48/58 (yes, that's fifty-eight teeth!) set of chainrings for my EZ-1 SC (steel), and was wondering if the front der could handle it. They come, BTW, from a crankset for a tandem BikeE. Yeah, I know, that span between the 32 and 48 rings is a big climb. To be honest, I'm not worried about that. I have little occasion to use the "granny ring" (or, in this case, since it's not that small, the "auntie ring"). I just wanna know if I can position the cage so that it'll throw the chain between the 48 and 58 rings properly. I know this will gear up my 'bent considerably, but that's exactly what I want to do.
I don't have the bike in front of me, so I'm not even sure how you physically position the front derailleur (or if it's even possible).
And yeah, I'll probably have to add links to my chain. How many?
58 should be no big deal. As I said Rans uses 60-62T cw with inner cw in the
low 20s without problems. As long as the Fr der can be lifted high enough for
clearance of the 58t cw it will work. Chain may drag on the bottom of the
cage in the 32 but you probably won't be in that CW for very long. If the
chain length is correct now, then add the difference in CW teeth: 52 to 58 is
6t, or 3" of chain (6 links). Might not be necessary to add any chain.
Cycle through the rear cassette and see what the R der does on the larger
two cassette cogs, if it straightens out the cage and pulls the cage forward
add chain. Bents have a lot longer chain line and chain slack so are less
sensitive to chain length. Chain flop is sometimes a problem as the R der
can't wrap up all the chain, so some bents have intermediate chain idlers
or even auxiliary R der chain cages to wrap chain. Steve
Yes, you are correct. I just got a Rans Tailwind and it has a HUGE chainring. The sizes are 42/52/62T If I recall the datasheet correctly. The cassette runs from 28T down to 11T. The idler cage on the derailleur is VERY long and misses the ground by only a couple of inces. There are two frame mounted idlers to conrol the chain as well. The whole thing works very smoothly. If you do the math and can do 120 crank RPM the speed comes out to around 40MPH. On the low end of things the lowes gear feels like a granny on an mountain bike. I have no difficulty in climbing moderate grades, just sit and spin. It all comes down to the throw on the front derailleur and how much slack the rear derailleur can take up. Good Luck!