thook

hello there,

i've contemplated a single speed for a long, long time. mostly i ride in the hills, so i'd always ditched the idea. but, there's areas without steep climbing, so i'm thinking what the heck....let's give it a try. haven't ridden one since bmx days of childhood

anyway, i want to do a trial set up and see how i like it. i have some 700c freehub wheels and thought maybe i could use a cog or two (modify hub interfacing on the cog/s) from an old six speed uniglide cassette for the rear. maybe two rings up front since i have a road double bottom bracket. the high fast gear and low gravel road/tired legs gear. point is, what do you think of running the UG cogs for the trial set up? they're not ramped. the teeth are just slightly twisted. if this is a sound idea, it gives me some trial gearing options without buying anything up front. and, use a regular six speed chain. i realize i'll have to get the chainline in order, but i have lots of cassette spacers to tinker things with

thanks for any input

andrewclaus

Would you keep the rear derailleur to take up chain slack, and allow front shifting? The high limit screw may have a limited range of adjustability--on mine, you can't shift it more than one or two cogs down from high. You can use a short piece of shift cable in a frame stop for rough placement, and used the barrel adjuster to fine tune it.

c_m_shooter

Cogs from a cassette will cut into the freehub body. Get a cog and spacer kit and use your derailer to keep it on there for the first couple rides. Look up a gear inch calculator and select a cog that will give you about 55 gear inches if you are mountain biking or 70-75 gear inches for road.

Amazon.com : Bibike Single Speed Conversion Kit 16T/17T/18T/19T/20T/21T/22T/23T Single Speed Fixie Cassette Compatible with Shimano Sram : Sports & Outdoors

Iride01 

Is the question that you want to simulate what a single speed bike will be like on the terrain you ride?

If so, why not put your bike into a similar gear ratio to what someone on your terrain with a single speed would use and then just not shift?

Wouldn't that replicate what you want to feel?

rhenning

As said above just put your bike in a gear and ride it for a while. 5 to 10 miles should be enough. Then decide if you need a lower or harder gear. When you find the gear you like then duplicate it on a single speed bike. Roger

squirtdad

I third the idea of just ride in a gear and maintain discipline to not shift. KISS priniciple (keep it simple stupid) and IME even cogs with only a slight twist will self shift to small unless you have a singulator or derailler to hold them

thook

i wasn't intending any kind of shifting ability other than loosen the rear wheel and moving the chain around by hand for either ring/cog combo. make sense?

thook

ohhhh...right! i forgot all about that being an issue. hmm...stinker

thook

well, sort of. i mean, i've done that on multiple occasions in the past when considering it all, but from what i'd read (in the past) the feel isn't really the same when derailleurs come into play. you lose some of that direct feel, right?

thook

hmmm....all good points. i wonder if i could straighten the teeth out on a cog without breaking them? what do you think?

thook

wait...why would i need a derailleur to keep the chain on the single speed cog that's designed to run without a derailleur? i realize i didn't mention it before, but i have horizontal drop outs

Iride01 

I don't really know why the DR will affect that.

However if you are talking about a proper fixie or track bike, I don't think they have a freewheel at all. So when you quit pedaling the cranks continue to turn until the bike is stopped. So in that respect it won't be the same experience.

Otherwise someone that has more experience on a single speed will have to say. My experience with them ended 55 years ago when I was 8 yo.

thook

oh, good heavens no...haha! that honestly seems like no fun at all. i remember when i was a kid and my first bike with a freewheel (bmx) was a revelation. a god send! my legs had freedom if that makes sense

from what i recall reading, the DR has a certain amount of drag/friction to it. as well, you have this chain with slack in it kinda delaying the response feel from pedal to wheel. however, that's not terribly important here, so no need to deliberate on it, right? i guess the most important reason for even posting was to find out if the UG cassette cogs were usable without the derailleur ...and....apparently not

in typing this reply, it just could occurred to me i have a few suntour freewheels. one in particular is put together like a cassette in that the sprockets install onto splines on the freewheel body. first sprocket is threaded and locks everything else on. i bet i could play with this thing for the trial set up. the sprockets aren't ramped or twisted. nice and straight what do you think of this?

Iride01 

I think the thing about the drag and power loss come under the heading of marginal gains. So I doubt for just finding out whether you can comfortably ride the terrain in one gear ratio that it will make much difference.

I wouldn't worry about the sculpting on the teeth. That, TMK, only comes into play when you shift, which you won't be doing.

Also, single speed bikes use cog and ring sized for a 1/8" wide chain, IIRC.

thook

squirtdad says the twisted teeth will cause the chain to automatically shift or fall down to the next smallest cog. so, can't use the UG cassette cogs. and, i think the ramping on hyperglide cogs (were i to use that) would have the same consequence....chain not wanting to stay on the gear

single speeds can get away with standard chain size for geared bikes. this i do know as there are SS sprockets that size. fixed gear i'm not so sure about. not going there, anyway

i'm sure your right on "gains". but, when i speak of feel i'm not speaking in terms of performance gain. quite simply just the "feel". but, i know what you're talking about with power transfer. i think that's probably a bigger deal, again, on fixed gear

Iride01 

But what squirtdad is talking about won't be a problem for just trying it out by staying in one gear in your bikes current configuration. If you don't like staying in any one of the current gear ratios on your bike for the entire ride while using the DR's, then you won't find the marginal performance improvement of a single speed to your liking either. IMO of course, I'm okay with you proving me wrong. But not in hypothesis, theory or BS'ing. You actually have to do it for real.

thook

oh, i get it. what squirtdad is saying is the chain won't stay on the cog without the derailleur to keep it there. my idea to run without a derailleur is the "no go".

to clear up matters, the intended bike isn't really even built, yet. iow's, no derailleurs on it. and, performance isn't a factor i'm weighing in on this whimsical idea. i have geared bikes for that. i just thought it'd be fun to put these extra parts together as single speed ride for simplicity's sake. just to kinda poke around without needing to keep up with anyone or any time factor. so, i think i'll try this out with the suntour freewheel i spoke of. i can play with chainline with ordering of sprockets on the freewheel body a bit.. ride it for a while and splurge on "real" single speed gear at some point. my tax return finally came in after months of waiting.

andrewclaus

Do the rear dropouts have enough room to take up the difference between front chainrings? Unless it's a half-step set-up, I'd be surprised.

thook

it's on old late 70's schwinn le tour with no derailleur hanger. i'd say at least an inch of adjustability, though. on the rings, not sure about half step, but i was thinking the change up having an equal difference of eg. 3 teeth.

45/14
42/17

those numbers are very arbitrary and theoretical. but, it's my understanding a set up like this would eliminate or minimize the amount of rearward adjustment. iow's, the axle would effectively stay in the same place. correct or no?

c_m_shooter

Those are a good place to be gearing wise. If you can convert the wheel to solid axle with nuts, it will stay. Quick release will not hold on standing climbs unless you run a surly tugnut.

thook

actually, i have a cheap 700c wheelset with nutted axles. black rims/machined sidewalls and stainless spokes. some generic ars hubs, but they spin nice enough. came off a walmart mongoose. otherwise, i have no other option to go solid axle

thook

Late to update, but I ran across this by "accident" while looking for something else...

https://www.mtbr.com/threads/homemad...73319&slide=11

With the nutted wheelset and the 5spd uniglide freewheel I have, I should be able to do this pretty easy. Other things have come up, so this had been put on the back burner.