Singlespeed & Fixed Gear - question for kids with older rdbike conversions

ok, i know i could/should prolly be asking this elsewhere, but i'm building up a fg/ss frame (still. money and time are both tight) so this is about a fg/ss project. plus, i know many ppl on this board have old frames that came with 27ers, and i know that many of you run 700c wheels on these frames.

anyway, some guy with the word "fix" in his name posted a great idea about a touring fixie, with spacing in the front fork to accept a rear wheel, for up to 4 different fixed gearing options. this was a very nice idea, and it got me to thinking about versatility. i want my current project to be my basic one-and-only bike. i'll prolly keep my current main rig around, for if'n my future main rig breaks down, or if i need to lend a bike to someone. but, the post i'd mentioned above has really got me thinking about how to maximize a bike's versatility.

so, i'm currently thinking about running the one frame with 2 different wheel/tire sets. the one would be a 32 holer with 16t cogs, fixed on one side, freewheelin' on the other. this'd get the usual slick, skinny tires that've been my weapon of choise the past couple of years. the other wheelset would be 36h, double-walled, reallly heavy duty, with an 18t fixed cog and a 20t freewheel. and big, big, big fat huge tires.

yeah, this is nothing groundbreaking; im sure many, many ppl do this. but i never have before; that's why i am asking advice.

i know i'd have to run front and rear brakes, as it'd be recomended for freewheeling applications, and i want the fatt tires for light offroading anyway. and i know i'd have to readjust the rear brake shoes whenever i changed cog sizes. i also figger i'll want 2 different chains, to accomodate the 2 different basic gear ratios. none of this should be a problem for me. i also know that, running 700c rims on a 27"er frame will necessitate longreach brakes. also, not a problem. i also know this could be a little expensive, but it doesnt matter much. i already have 2 wheelsets; i'd just need to buy an extra hub and the various cogs/freewheels.

i guess, my questions are as follows:

-i know you'd have to see the frame to know for sure, but how much tire do ya think an old nishiki tenspeed frame, fitted with 700c wheels, will allow? there's soooo much clearance left when i throw my 700'c with 25mm tires on the frame. are the nominal specs given to tires accurate? if so, i could prolly fit like 45mm tires in there, if my ruler is to be believed. but i dont think i'll want more than 37 or 40mm tires. will fitment be a problem?

-what size chainring ought i use, keeping versatility in mind? i currently run a 48/16 fixed, and it's fine by me. i was thinking of dropping down anyway, to keep my spin up. so, i'm hoping i could use a smaller chainring anyway, but i want to maximize the all-range ability of the bike. i'm thinking, if most ss mtnbikers use a 26" wheel with 2" tires, 175mm cranks, and a 32/16 ratio, they're pushing 51.9 gear inches. so, if i'm rocking 700c wheels with 38mm tires, 170mm cranks, and a 43/20 ratio, i'll be pushing 58.7 gear inches. i'm thinking that'll be fine on the relatively flat trails of south jersey, but i could certainlybe wrong!! regardless, it'd be a big jump down from the 79 gear inches i'm rocking now, but to be fair, the trail-riding i do these days is done on ym geared mtn bike. which i dont like very much. i guess i mostly want to ride the 18t fixed cog out to the very flat but very scenic trails of the pine barrens (New jersey) and switch to the 20t freewheel to get bizzy.

-are there any other pitfalls i'm missing?

thanks in advance for any advice. i'm sorry this post is so wrong; i just wanted to prevent ppl from wasting time telling me stuff that i already know (or, already think i know). the only way y'all can know where i'm coming from is if i'm forthcoming with my prior knowledge.

-rob

1. You shouldnt need to change adjst the r. brake after changing cogs...thats the beauty of an older roadframe over track ends.
2. My one-and-only bike uses 27x1 1/8 on the road, and 700cX35 panars on the trails (actually, sometimes even the 27 inchers). They're plenty wide for most trail riding, depending on which 'pine trails' youre referring to (The trails in wharton/atsion area are pretty thick sand, and 35 would NOT be wide enough, but then again, 59 inches would do you no good anyway.
3. 700c on a 27 frame does not ~necessarily~ necessitate long-reach brakes (common misconception from many people who've never done it). Theres only 4mm dif between the two wheels. If you have 4mils of adjustment in your calipers/youre golden.

the only time when you are really screwed is if you have a touring bike like me that has long reach brakes already with 27" wheels...then you need the really ****ty 73mm sidepulls for it to work with 700s...grr...

1. You shouldnt need to change adjst the r. brake after changing cogs...thats the beauty of an older roadframe over track ends.
2. My one-and-only bike uses 27x1 1/8 on the road, and 700cX35 panars on the trails (actually, sometimes even the 27 inchers). They're plenty wide for most trail riding, depending on which 'pine trails' youre referring to (The trails in wharton/atsion area are pretty thick sand, and 35 would NOT be wide enough, but then again, 59 inches would do you no good anyway.

what kind of gearing do you use on the trail? i was planning on riding fireroads in the pines sort of in the crotch of rte 70 and rte 72, and similar. there arent alot of serious inclines, but the sand is rough. my experience with sand on a mtn bike is that really low gears spin thru sand, rather'n biting in, so i avoid grannies in sand. i also was gonna ride hardpack silly south jersey trails in little parks and whatnot. south jersey needs more non-paved land.


3. 700c on a 27 frame does not ~necessarily~ necessitate long-reach brakes (common misconception from many people who've never done it). Theres only 4mm dif between the two wheels. If you have 4mils of adjustment in your calipers/youre golden.

yeah, but i threw a front brake on the fork with a 700c wheel, and no dice. i need long-reach brakes, i fear.

thanks for your help!
-rob

I run 43x18/20 offroad (x16 on road). Usually on the 18 unless really hilly. Those fireroads are pretty solid. Rough, but solid (I was referring to the loose-beach sand common a little farther south off of 206; Pain in the arse even on my wifes 21 spd MTB with 2.25s; I dont even bother on my rig down there). I think you'd be more than fine on that with 59 or even 65 on that gravely stuff.

Hardpack trails in SJ parks? Forget that... cruise up to wissahickon valley in phila....Got 5 1/2 miles of flat, carless cinder, with plenty to look at (jogging by, yaknowhatimean). Miles of singletrack on either side of the flatpath. Worth the ride over (or even the drive if youre one of those types).

I run 43x18/20 offroad (x16 on road). Usually on the 18 unless really hilly. Those fireroads are pretty solid. Rough, but solid (I was referring to the loose-beach sand common a little farther south off of 206; Pain in the arse even on my wifes 21 spd MTB with 2.25s; I dont even bother on my rig down there). I think you'd be more than fine on that with 59 or even 65 on that gravely stuff.

Hardpack trails in SJ parks? Forget that... cruise up to wissahickon valley in phila....Got 5 1/2 miles of flat, carless cinder, with plenty to look at (jogging by, yaknowhatimean). Miles of singletrack on either side of the flatpath. Worth the ride over (or even the drive if youre one of those types).


i hear ya. wissahickon'd be worth the ride for me; im in camden county, so that's no big ride at all.

i was experimenting with my mtn bike, and i'm thinking 59inches will be fine for me. and, when it's not, i dismount, shoulder the rig, and jog up the hill. no biggie.

south jersey's bullshhh parks aren't worth riding to just to ride, but i like to bomb thru them if i'm not in a hurry, and riding by anyway. it just isnt very fun to do so on 700x25's, especially when the flatgods hate you. and, lo! they hate me.

where in nj are you?

-rob

My "main" bike is a fuji s10-s, 70's roadframe, which is running 700x28's and a front sidepull. There's lots and lots of room for fenders or a bigger tire if u wanted to do something like that.
Freewheels come in like 16, 18, 20, 22 as common sizes and the same with track-- i would prolly go with a 44:16 fixed and like a 44:22 free if you wanted to do it with some sort of cross tire 700x32 or so-- which would be kewl.


Hmm, ok now u got me thinking.

My "main" bike is a fuji s10-s, 70's roadframe, which is running 700x28's and a front sidepull. There's lots and lots of room for fenders or a bigger tire if u wanted to do something like that.
Freewheels come in like 16, 18, 20, 22 as common sizes and the same with track-- i would prolly go with a 44:16 fixed and like a 44:22 free if you wanted to do it with some sort of cross tire 700x32 or so-- which would be kewl.


Hmm, ok now u got me thinking.

yeah, it is sort of a thought-provoking concept. i'm thinking 43/20, but i imagine 44/22 would be only slightly lower-geared than 43/20, and i've had trouble finding affordable freewheels bigger'n 20t. yeah, ENO makes 'em, but they cost like $70. a bit rich for my blood.

i'm thinking i could fit 40's on my frame, but i'm likely to go with 37's.

i'll keep ppl posted...

-rob

59 should be more than fine around here. I'm in Medford; about 10 miles from aforementioed soft sand.