Just A Few More Inches Baby

[gb155]

My Current SS is running

42/16

That gives me 69.2 GI and 18,5 Mph @ 90 RPM

I want to go to 42/15

Am I right that it will give me the following:

73. GI and 19.8Mph @ 90 RPM ?


If so, do I just need to change the cog, or do I need to do something to the chain etc too ?

Thanks

Gaz

 

[Rob3rt]

As your SS is a conversion with diagonal or vertical dropouts, you will need to shorten the chain a bit to take up the slack introduced by the smaller sprocket.Track dropouts would allow you to just pull the wheel back to take up the slack, this advantage vs converted road frames is what I was referring to as one point re converting the CAAD.

 

[gb155]

As your SS is a conversion with diagonal or vertical dropouts, you will need to shorten the chain a bit to take up the slack introduced by the smaller sprocket.Track dropouts would allow you to just pull the wheel back to take up the slack, this advantage vs converted road frames is what I was referring to as one point re converting the CAAD.

My Pug allows this

but the wheel is all the way to the back as its a little slack now (The chain) so with a 15T I need to remove a link ?

 

[MacB]

My Pug allows this

but the wheel is all the way to the back as its a little slack now (The chain) so with a 15T I need to remove a link ?

yep, remove a link and, depending on length of dropouts you may need to use a half link. Removing a full link should be 1 inch off the chain so about 1/2 inch variance in dropout position, a half link allows for variance of a 1/4 inch only. For example, if your chain is good but the axle is right at the end of the dropout removing a full link may take it too far forward.

 

[Rob3rt]

Yeah, remove a link or 2, don't know exactly how many you will need to remove.

 

[Sh4rkyBloke]

Or change the crankset and get a 48 up front. I run 48 x 16 in Manchester and it's nice for cruising around the 20mph mark with no probs, with occasional burst up to the high 20s (I think it'll run at about 29mph at 120rpm but my pedalling is not smooth enough for this yet).

 

[Rob3rt]

I agree with Sharkey with that gearing being okay in the city, but Gaz likes hills. I've dragged my 48:15 over into the peaks and I'll tell you now, being over taken by a lady walking her very young (toddler) daughter on a 12-15% climb (according to Garmin) is embarassing.

 

[gb155]

Agreed, as it stands to get to work and back I need take in an 8% hill, Im sure that wouldn't be too much of an issue, but 99% of the time I take the longer way to work and there is at least 1 x 11%er so dont want to jump up too high of a gear.

In other news Im hoping to have my Cannondale back for weekend WHOOOOOT

 

[McrJ64]

My Current SS is running

42/16

That gives me 69.2 GI and 18,5 Mph @ 90 RPM

I want to go to 42/15

Am I right that it will give me the following:

73. GI and 19.8Mph @ 90 RPM ?


If so, do I just need to change the cog, or do I need to do something to the chain etc too ?

Thanks

Gaz

 

[McrJ64]

I use 42 * 17 for going to work with the bike rigged out in work mode. I strip it down at weekends and used 42*16. The vertical dropouts allow me to move the wheel without adjusting chain lenght. On 42*16 I get up to low 20s mph to stay with those on gears. I don't know how fast I spin but am reasonably comfortable up to 22mph. If you could get higher revs, it would give you more flexibility to stay with others on the flat without losing the ability to climb those hills when you meet them.

 

[ColinJ]

I use a 39/15 gear on my s/s bike (just a smidge lower than a 42/16). I find that a good compromise ratio. I can get up moderate hills on it and spin away at a comfortable speed.

I averaged 18 mph for 1 hr 50 mins on it at the MacRide on the Silverstone F1 circuit last year on a very windy evening.

Sure, I begin to spin out when trying to go faster than about 25 mph, but if I geared up I'd be struggling uphill or into headwinds.

I find even 39/15 quite slow from a standing start so I wouldn't fancy increasing it by 8% to 42/15 for city centre cycling. Slow starts away from every set of lights, roundabout, junction? I'd rather be able to sprint up to 20 mph pretty quickly and hold it there.