Biggest chainring

dudi

Hiya,

I have recently bought my first bike, a CB san remo, nice chunky sturdy frame so even I shouldn't break it. I use it for a daly commute and weekend rides.

I have a problem with top speed though, i seem to "spin out" quite regularly on longer rides, and would like to fix this.

now, the rear gears are apparently a 7 speed block, which is a pain, because I can't easilly upgrade the gearing there. the smallest cog is a 14tooth one.

I've been looking at getting a larger front chainring to give a better gear ratio, at the moment it has a 39/53T. I cant find anything bigger than 53t, is this right? am I at the limit of my gear ratio without faffing about with new hubs and all that goes along with it?

Any help or suggestions are greatly appreciated.

dudi

Has anyone ever seen a 7 speed cassette hub? I have found a 7 speed road cassette but cant find the hub to go with it...

Dave L

dudi wrote:

Has anyone ever seen a 7 speed cassette hub? I have found a 7 speed road cassette but cant find the hub to go with it...

I still have one from the 80's on one of my bikes, but you can use a 7 speed cassette on 8/9/10 speed hubs with a 3mm spacer. (Though not the 10 speed only hubs such as some Dura-Ace etc).
For larger chainrings, TA make them with up to 58 teeth (at least) to fit Shimano chainsets.

e999sam

Don't get a bigger chain ring learn to pedal faster. At about 90 rpm in 53x14 you will be doing about 27mph. You should be able to hit 30+ in that gear.

Big Red S

dudi wrote:

Has anyone ever seen a 7 speed cassette hub? I have found a 7 speed road cassette but cant find the hub to go with it...

If you're looking at replacing the hub, you might as well replace it with an 8/9 speed one. You can fit 7 speed cassettes on 8/9 speed freehubs - most cassettes come with the relevant spacers now.

You _can_ get bigger chainrings, but they may well foul your frame and your knees certainly wont appreciate it. You should be riding at about 90rpm (so 1.5 crank revolutions a second) - it's much more efficient (though doesn't feel it to begin with) and better for your knees.

dudi

Oh really? excellent, if it does get too annoying i'll do the rear instead of the front... sounds like a better move.

if 90rpm is the most efficient, then perhaps I am OK, it just feels like i'm peddaling like a crazy. but I must be about the right speed as I get about 30-32mph on the flat at peak. 25-28 as a fair effort.n but only for short periods of time. I'm too fat and unfit to do that speed for much more than a couple of miles!

thanks for the guidance guys.

Monty Dog

Most people who race only use a 53 tooth chainring - it's big enough to get up to a speed in excess of 40mph on the flat if you can pedal hard enough, but that would be with a rear sprocket of 11 or 12 teeth. Probably the smallest you'll find in 7 speed will be 12 tooth. BTW 'spinning-out' on the road in my experience is about 180rpm - keep working on your pedal stroke, but consider 90rpm to be a comfortable cadence, not a 'fast' one.