Singlespeed Conversion

krakow

Cross-posted from 'Special Interests' as no-one was biting there... I'm thinking of converting my current everyday bike, a Dawes Discovery 501 which I have been riding into the ground for the last 8 or so years, to singlespeed.

Once again the drivetrain has reached a serious state of disrepair and this time I'm not particularly keen to get it all replaced yet again due to the cost. I've ended up using increasingly fewer and fewer of the gears over the years and am pretty sure that I could survive with one, especially taking into account the weight and maintenance benefits.

I'm wanting to canvas opinions on the various singlespeed conversion kits available.

It's got vertical dropouts and runs a very basic shimano 8-speed freewheel cassette as far as I know, so a chain tensioner and spacer/cog kit is what I have in mind. Of the various kits available, are there any particular recommendations or ones to be avoided? The readily available options seem to be:

+ On-One singlespeed conversion kit and their couple of doofers
+ DMR singlespeed conversion kit or their more expensive tension seeker2 and separate spacer kit
+ Charlie The Bikemongers singlespeed conversion kit, which I think uses Gusset stuff
+ Surly Singleator and a spacer/cog kit

Is there anything to choose between these, or are they much of a muchness? Other suggestions welcome of course. I began wondering if a not-too-fancy new singlespeed rear wheel might actually be a viable option, but I'm not sure how much such a thing might cost.

Thanks

Richard891

Hi,

I used Charlie the bike monger's SS conversion kit and the Surly Singleator. I was converting a mountain bike (bought in Decathlon in France) which I'd been commuting on with schwable city jet tyres. Like you say, after a while I realised I hardly used any of the gears for this job which got me thinking about the conversion.

Unfortunately I got carried away, filed the gear cable routers off the frame, got it powder coated bought new brake levers, grips, saddle, crankset (I bought a cheap truvativ triple off chainreaction cycles and took the small rings off it, you need Charlie's long chainwheel bolts for this, dedicated SS cranks are expensive) and a rigid fork off eBay. I'm still using the old SRAM 7/8 speed chain I had. By the time I'd finished I could've almost bought a new single speed bike with the money I'd spent!

Charlie the bike monger gives you two sprockets, a 16t and an 18t. I'm running 42x16, which I can monkey up all the hills around the town and don't often spin out unless I'm in a hurry.

Was an interesting project, just went over budget...

RR

krakow

Yeah, that is a potential worry. i just stumbled across this blog post: http://blog.2280.net/?page_id=124 which, while very informative, also worries me a fair bit that it could all end up a lot more complicated and expensive than I'd like.

I'm so sick of my dying drivechain though that I think I'm going to have to go through with it.

caw35slr

I successfully converted a mountain bike to SS for training/pub using the OnOne freehub converter and a Doofer. The key was getting the spacers the right way around and tinkering with the Doofer adjustment until it was just right. The crank was a stripped-down Deore triple with shorter ring bolts from ChainReaction. Chainline wasn't perfrct but it was quiet and never came off, so good enough for pupose.

http://picasaweb.google.co.uk/caw35pica ... 0781205938

Sheldon Brown's SS article is worth a read:

http://sheldonbrown.com/singlespeed.html

krakow

The current cranks and chainring etc. seem to be a one-piece cheap shimano thing on mine, which is another potential issue, as they're probably not really much cop and ideally would be needed to be replaced too.

Dai_bach

I bought the DMR conversion kit, including spacers. Didn't get on with the chain tensioner as its range is quite limited and you have to remove the QR every time you want to take the wheel off, as well as loosen the bolts on the tensioner. Changed to a tension seeker and got a half-link chain which works very.

Doing a conversion is ostensibly very easy. Fiddling round with chain lengths and sprocket/chainring combinations takes a while though.

krakow

It seems like a tensioner that can tension upwards would be preferable, so as to give greater contact between the chain and the cog, and that something spring tensioned would also be good, so that it can auto-adjust rather than having to be fiddled about with manually to get the correct tension. Right?

The DMR tension seeker 2 fits the bill, but it's getting relatively expensive at £35 for the tensioner alone. Is it worth paying more for these features, or am i barking up the wrong tree?

andrewgturnbull

Hi there.

If you're looking to save money, why not use your existing rear derailleur as a chain tensioner?

Cheers, Andy

krakow

I think that the rear derailleur is one of the prime sufferers in the death of the drive train type situation that is the original motivation for the singlespeed conversion. The upper jockey wheel is incredibly loose. I assume this would make it less than ideal for such purposes?

andrewgturnbull

...er no. I think you just need the lower jockey wheel, just thread the chain directly round the bottom of the lower wheel and bypass the top one.

krakow

I'll have another read of Sheldon on the subject, but I'd probably be willing to stump up the cash for a dedicated tensioner if there's any benefits to doing so; I'm suspicious of my derailleur being very much worse for wear. Finding the balance between not spending too much and getting a set-up that's worth having is the tough bit.

Richard891

I'd recommend the Surly Singleator chain tensioner, though it's probably top of the range. As to whether you want to tension up or down, yes up is probably better, but you may find due to the shape of your frame that down is the only way. Mine's tensioned down and I've not had any problems.

Regarding the crankset, the one I replaced was a cheap riveted triple, from which the indivdual chain rings could not be removed without destruction. However there were a few flatted teeth on the big ring from hitting rocks on the trail, so it needed replaced anyway.

In total I probably spent about £200 on the conversion and tricking out the bike a little. However, it's my main mode of transport for getting to work and messages around the town, and I consider it money well spent, especially since maintenance involves no more than cleaning and re-lubing the chain once in a while. Plus, I really think riding SS has given me more leg strength and more leg speed, which is transfering across well when I'm out on my road bike.

whyamihere

The DMR STS is excellent. The spring tensioned ones can have a tendency to flap about, the STS is solid. If you're running a decent chain line, you can get the roller directly under the chain, and using washers I locked the position of mine so that the chain cannot possible move, and when combined with correct chain tension nothing short of a bomb blast can derail my chain.

A word of warning about chainrings... On my SS MTB conversion, I use a 38/12 gear, as my area's pretty flat. At first, I tried a light build, with alloy chainring bolts and a Blackspire DH ring. Bad idea... Going up a steepish hill, the chainring bolts exploded and destroyed the chainring. The ring ended up looking like a Shimano Biopace, but with nasty fractures going through it where the metal had bent. Bought a Middleburn ring (more metal) and good quality steel chainring bolts, and I've had no further problems.

meagain

"The DMR STS is excellent."

I'd been trying to remember which of the 3 or so that I've tried was the best - it was the DMR STS.

krakow

Thanks for the input. I just invested in the all-in-one DMR kit, which includes their STS tensioner, a 16T cog and a couple of spacers. Also got a new £15 SRAM 8-speed chain (I debated whether to hold out and go online for a singlespeed specific chain, but figured supporting the LBS was worth it and I probably won't notice the difference - am I right?).

Unfortunately I've just hit the major snag that the allen bolt on my rear skewer is completely stripped and I'm utterly failing to get the rear wheel off. Such frustration... Any solutions before I head back to the LBS to fork out for them to sort it some magical way?

meagain

Do you mean that the skewer uses hex-head bolts that are held in captive recessed washers (I can picture this, but I'm not describing it very well I fear!)? If so, can you not drill out the heads?

Got any pic links to the problem area?

krakow

I'm not sure. It was a security skewer, the kind that needs an allen key to loosen & tighten it, but I'd previously managed to strip the bit where the allen key was meant to go unfortunately. I ended up taking it to the bike shop and they were able to get it free using a hefty pair of pliers on the other end of the skewer (I'd tried this, but didn't have the technique or strong enough pliers to succeed).

I'm also feeling pretty wretched, because the subsequent singlespeed conversion operation was an abject failure. I managed to kick off by breaking both a chain and a chain tool, then followed that up by resolutely failing to remove the cassette from the freewheel. In a fit of panic and despond, with pieces of my bike lying about me, I swallowed my pride, loosened my wallet and headed back yet again to the bike shop. Hopefully it will be ready tomorrow. I really wish I'd been able to handle it myself, but I definitely felt out of my depth when it all failed to go as planned and I couldn't face the prospect of being stranded for any significant period without my bike. Sigh.

meagain

Oh dear...but full marks for trying!

krakow

Thanks for all the tips and advice. It was a shame I didn't manage it myself, but it all seems to have worked out in the end.

The bike shop were very good and did the job for me by late morning the next day, so that I could pop along on my lunch break to collect the newly singlespeeded bike (and it was a lot less financially damaging than I'd feared).

Only a couple of days in, but I'm really really pleased with the change. The bike is noticeably lighter without all the geared equipment on and looks a lot better to me. I'm really enjoying riding singlespeed too, it's just as much fun as I'd hoped, and as yet not so difficult as I'd feared. Without the option of easing off and shifting down, I'm being forced to maintain a higher, steadier cadence and consequently a higher speed, so as to maintain my momentum. Early days yet, but I'm currently really pleased with and excited about the switch to singlespeed.

It's such a revelation coming from my worn out old drivetrain in particular. No longer having to worry about the chain skipping or gears failing to engage is taking some getting used to; I can't believe how long I survived like that.

I'm currently running 38x16 on 700Cx32 tyres, which, according to Sheldon's gear calculator, is just a smidgen over 64'' and I've so far managed to get up the worst of the hills on my regular commuting route (albeit very very slowly) and even made a medium-sized shopping trip to Tescos, managing to haul back a couple of panniers and a rucksacks worth of shopping without grinding to a halt. On the flip side, I'm spinning out at just over 20 mph on the downhills and having to let the freewheel kick in.

I'm planning to build up a fixed-gear bike next, so hopefully a few weeks on the singlespeed will be not just good preparation, but will also aid in my choosing the right gearing for the fixed-gear bike.