single speed practice - what gear?

TRADESIZE

ok I fancy a bit of a challenge to set myslef, on my 20 mile round trip ride to work.

I quite fancy a charge plug, obvisuly this is single speed but I need to know i can cope with it first before I consider buying one!

my current bike has the following gears:

CASSETTE Shimano HG30 11-32
CRANKS Shimano FC-M191 28/38/48

the charge plug has a 42 / 16 tooth ratio

what cogs do i need to use to get my current bike to the same equivalent gear as a 42/16?

many thanks

nicklouse

42/16=2.625

so 2.625X rear cog = front cog

assuming the same size wheels.

TRADESIZE

ah ha good point;

my bike wheels:
RIMS Alex ACE 18 700c

charge plug wheels:
Wheels: Alex DM18 700C rims

sorry to sound thick but what do you mean by so 2.625X rear cog = front cog?

nice mardave mini stock in your avatar by the way (looks like one anyway)

nicklouse

basic math.

put in your cog at the rear and see which font one to use. or rearrange and to give the rear cog to use with whichever front cog you want to use.

ansbaradigeidfran

Rearranging to calculate with one of the three chainwheels makes for less trial and error, as there's seven(+?) rear gears that might fit the bill.

front cog / 2.625 = rear cog

lost_in_thought

Or, you could use a GI table... a 42/16 is 71 (ish) GI, so with your cogs to get a 71" gear, with a front 48T chainring you could go for 68" with a 19T sprocket, or 72" with an 18T sprocket.

Hope this helps!!

Here's the link for the table: http://home.i1.net/~dwolfe/gerz/

BUICK

Just get the Plug! You can handle it...

BUICK

... riding fixed is much easier than doing the math for gear inches :shock:

don_don

Don't bother trying to do the sums yourself. Go here: http://www.sheldonbrown.com/gears/ and just input the figures. Don't forget to change the gear units from 'gain ratio' to 'gear inches'

There's plenty of explanation on the site about how it all works. Hope this helps

Littigator

yeah just take the plunge and get stuck in it really is no big deal and it's a lot of fun!

itboffin

How hilly is the route?

42/16T might be a little spiney if it mostly flat, although as a lot of people on this forum will tell you this IS/ISNT a bad thing - don't ask.

I personally went from 42 to 44 to 48 to 52 erm cough to 60 and back to 52/18T for the winter

[Put's on lab coat]

Now what we have here is a selection of front a rear sprocket combinations, showing the GI and Ratios as well as the speed you will travel in MPH (naturally) @ 60, 70, 80 & 90 RPM

        Ratio	  GI      60rpm   70rpm   80rpm   90rpm
48/16	3.00	   78.80	14.07	16.41	18.75	21.10
48/17	2.82	   74.17	13.24	15.44	17.65	19.86
48/18	2.67	   70.04	12.50	14.59	16.67	18.75

44/16	2.75	   72.23	12.89	15.04	17.19	19.34
44/17	2.59	   67.98	12.14	14.16	16.18	18.20
44/18	2.44	   64.21	11.46	13.37	15.28	17.19

42/16	2.62	   68.95	12.31	14.36	16.41	18.46
42/17	2.47	   64.89	11.58	13.51	15.44	17.38
42/18	2.33	   61.29	10.94	12.76	14.59	16.41

[/Takes off lab coat]

I really need to get out more often :oops:

biondino

48/17 would suit a flat ride for an averagely fit rider, I reckon.

ride_whenever

Sounds about right, I run 46/16 which is 75.6 IIRC and that works even up some fairly steep hills.

wgwarburton

itboffin writes:

> 42/16T might be a little spiney if it mostly flat, although as a lot of people on this forum will tell you this IS/ISNT a bad thing - don't ask.

Not going to weigh in here, I don't think the OP wants this much detail (correct me if I'm wrong!).

Here's an interesting paper for anyone feeling Boffinish:

http://www2.bsn.de/Cycling/articles/cadence.html

Personally, I reckon spinning is easier on the joints than mashing, so I prefer a lower gear. In retrospect, though, I've been working on my pedalling technique for much longer than I'd realised, so I'm comfortable at quite high cadences when descending/sprinting for "short" periods. I'd rather tire out my muscles than strain my joints.

Cheers,
W.

itboffin

WGWarburton wrote:

itboffin writes:

> 42/16T might be a little spiney if it mostly flat, although as a lot of people on this forum will tell you this IS/ISNT a bad thing - don't ask.

Not going to weigh in here, I don't think the OP wants this much detail (correct me if I'm wrong!).

Here's an interesting paper for anyone feeling Boffinish:

http://www2.bsn.de/Cycling/articles/cadence.html

Personally, I reckon spinning is easier on the joints than mashing, so I prefer a lower gear. In retrospect, though, I've been working on my pedalling technique for much longer than I'd realised, so I'm comfortable at quite high cadences when descending/sprinting for "short" periods. I'd rather tire out my muscles than strain my joints.

Cheers,
W.

Hello Buns that comment was specifically aimed at you but then I guess you knew that :P

TRADESIZE

thanks for all the info.
according to your sums i think this is right in terms of being the right equivalent to 42/16 on my bike:

2.625X rear cog = front cog
using that rule:

2.625 x 18 (rear cog) = 47.25 - I have a 48 tooth outer crank so I guess that the closet I'm goona get to 42/16

Does that sound right?

I guessed today and tried to stay in one gear all the way, I cant remember what gear I chose but the gradients going up hurt and the gradients going down seemed to be lacking on top speed. I'll give it a go on 18/48 for tomorrows ride and TRY not to change. Pain is all in the mind anyways huh?

wgwarburton

Hi,
Yup. 42x16 is slightly lower than 48x18, but the difference is tiny- you won't notice.

When I was looking to go fixed I went through this and found at the end of it that it was easier to ride a fixed than to ride a single-speed without freewheeling, because you don't need to push on the pedals all the time to maintain the connection. 'Course if, you freewheel it's fine, but where's the fun in that? :-).

itboffin writes:
> Hello Buns that comment was specifically aimed at you but then I guess you knew that

Crossed my mind... not that that takes long, mind you...

Cheers,
W.

TRADESIZE

i didn't ride today because my two sons kept me up all night and i had about 2.5 hrs sleep. Driving the car was like pulling teeth

I found a used twice immaculate charge plug about 5 miles from my house for £250!!! Why oh why do these things come up when I am totally broke