Project #3: Singlespeed MTB

A singlespeed MTB.. why didn't I think of it before?  Well.. possibly because it sounds ludicrous.  A bike designed for cycling up and down large hills, reduced to a single gear?  Surely that's defeating the entire object of the bike!  I may as well buy a flippin BMX!

But it's not quite as simple as that.. MTBs aren't just gears - they're also frame geometry, wheels, tyres, and suspension.  Unlike the racing frames, they're built to ride over whatever is thrown in front of them.  This became apparent when autumn got into full swing, and I found myself cycling over slippery fallen leaves on slim road tyres and a rigid frame.  It was scary!  I was constantly worried that the wheels would slip from under me, and I'd end up under a bus.

The front wheel issue got me back on the MTB, and I realised how much better it was at dealing with leaves.  I missed the singlespeed, though.  I missed it's direct power, and the general feel of riding without having to worry about anything gear related.  Sure, I could ride without changing gear, like I generally did anyway, but it wasn't the same, somehow.

Onto the conversion...

Shopping list:

DMR STS Combo Kit (some spacers, a 16T cog, and a tensioner) - £33

Cassette removal tool - £6

A chain - £6

Total cost: £45

First, I took the rear wheel off, and removed the QR skewer.  The cassette removal tool included a guide, so there was no need to clamp it in place with anything. It slotted nicely into the hub.  Then I used a chain whip, which I've had for years for removing oil filters from cars, and an adjustable wrench to unscrew the locknut.

With the locknut off, the cassette came off easily, with the 11 and 12 tooth cogs falling away from the rest.  The other six cogs were screwed together using a bolt with the tiniest hex diameter I've ever seen.

Next, I added a couple of the larger spacers, put the cog in, and added the rest of the spacers, and put the locknut back on.  I put the wheel back onto the bike, and tried to tell if it would be a decent chainline..  I still have no idea!  It looked kind've straight, but I know from experience that it's very hard to tell by eye.  It wouldn't be hard to adjust later, so I left it like that, and turned my attention to the deraileurs.

The deraileurs came off simply enough - just some bolts to undo.  I wasn't intending to keep the gear cables, so I snipped them using my brake cable cutter.  Did I mention that I was doing this in my lunchbreak?  No time for fiddling with tiny screws and uncooperative wires!

With the deraileurs off, I attached the tensioner.  There are two parts to it - one bit that slots into the dropout, and is secured using the QR skewer, and the tensioner arm itself, which screws into that, and to the gear hanger.

Next was the chain, and this is where things started going wrong.  The problem with mountain bikes is that most of them, including mine, have vertical dropouts.  That means the wheel can't be moved back and forth to take up chain slack, so a tensioner is required to do that job.  When trying to join the chain, the links were only 3mm away from a near perfect fit, but they were 3mm too far apart, not too close.  I had to use the next link down the line, which made the chain VERY slack.  The chain was so slack that the tensioner couldn't operate in it's intended configuration (pushing up on the chain), as it hit the chainstay before taking up the slack, so I had to set it to push down instead.

That setup actually worked!  Well..  sort-of.   It turned out that 42-16 was a bit of a rubbish gear ratio, equivalent to 5th gear, but it felt more like 4th, and pedalling felt clumsy and faster than necessary.  That was going home, which is entirely uphill, so I was dreading trying it on the way into work!  Another problem is the width of the chain - it's exactly the same width as the groove in the tensioner, so it's being slightly gripped by it.  The sound it makes as it grips/releases the links is very weird!  Kind've like a fluttering noise.  To fix it, I can either buy a thinner 9/10-speed chain, or shave the tensioner a bit to make the groove wider.  I'm going for shaving, using a file!

So, once home, I got the old cassette out, found a suitably tiny hex key, and split the cassette into seperate cogs.  Seperate, filthy cogs. Some soap and water cleaned them up, and I had myself a 14-tooth cog for use in the morning.  It was getting too late to work on the bike, so I intended to do it during my lunch break..

Well, 4 miles on a 5.2 gear ratio, going downhill, put paid to that idea.  It was horrible!  I swung into Cringle Park, in Levenshulme, turned the bike on it's back, and got the tools out again.  Wheel off, locknut off, spacers off, 16T cog off, 14T cog in, etc, etc..  As an added bonus, the change in cog size meant the chain could be reduced to a less flappy length.  The tensioner was still close to hitting the chainstay, but it was doing it's job.  The ride from that point was far more agreeable!  :)

On my lunchbreak, I decided to try out a different gear ratio, using the 34-tooth chainwheel and the 12-tooth cog, to see if it improved the chain slack at all.  It didn't - it would've been extremely flappy again, so I left the chain the length it was, and went back to 42-14.

So, I guess I'll have to live with it the way it is.  I'd like the chain to be a little shorter, but it's just not possible with the cogs that I've got, and I'm not sure I want to go off buying cogs to see if they improve matters.  It's not bad, as such.  Just not perfect!

There are two final tasks to complete, now.  The 24 and 34 tooth chainwheels are still attached, and I want to take them off.  The crank arm isn't coming off without a fight, though.  The mallet just isn't getting through, so I need to ride it for a bit with the nut off.  I might spray some WD40 into it to see if that also helps.  I'm not sure if I should attempt this on the way home..  it'll probably wait until the most dangerous point before my entire chainset falls off.  :P

The other task is to replace the brakes.  My bike has Shimano Altus combined shifters and brakes (ugly things), so I can't just detach the shifters.  I've got some Acera levers on order, which have the added bonus of looking much nicer!

All in all, the conversion has been relatively pain-free.  The bike hasn't been rendered unusable for any length of time, which is a win in my book.  :)  

My MTB, back in the day

It does leave me with a new problem, however..  Apart from the tyres, all of the components are original, from when I bought it 8 years ago.  They're all a bit scuffed, and are making the bike look very shabby!  I found some photos of the bike from 2009, and it was looking much snazzier, despite having been riden through a muddy forest for a few hours.  So the new task is to start replacing parts to make it look a bit more presentable. 

At least I don't have to worry about replacing the deraileurs!

Here we go again..

I was supposed to sell my Hardrock once the second bike was completed...

Why would I need two geared commuter bikes?

I never get a chance to go offroad anymore, so it'll be useless..

It would help pay for the second bike..

It would quell some of the rage my partner was feeling toward me spending so much money on bikes..

She wouldn't like to see my browser search box..

"MTB singlespeed"


Here we go again!

Project #2: Carlton Thingumybob

So, the singlespeed project is a success!  So far. 

This is good news, because the singlespeed isn't my only ebay project - there is another!

Enter the arena; a Carlton somethingorother.  Built in Worksop in 1974, using 531 tubing, possibly resprayed metallic blue at some point, with no model name anywhere, and a frame layout that doesn't match any other Carlton that I've found pictures of.

No seat yet - I need to get the post measured

I guess the first thing to explain is why I thought it necessary to buy another bike.  I already had two, after all!  Well, at the time I was still pondering singlespeed or geared.  I wanted to try both options, and that meant either swapping components around on the one bike I did have, or buying a whole other bike.  I don't need much of an excuse to buy new things, especially when the new things are lovely retro bikes!  :)

The identity of the new frame has bugged me since I bought it.  I've hunted high and low for similar bikes, but none quite match.  The main issue is the rear brake hanger.  Almost all Carltons have a cable bridge above it, which aligns the cable directly above a centre-pull calliper brake.  Mine doesn't have one, which leads me to believe that it originally had sidepull brakes, or something attached to the seat bolt.  I've seen plenty of other 531-framed Carltons, but none that I've seen are missing the cable bridge.  The ones that are missing it are much older, or have different lugs/seat stays to mine.

So I don't know what it is.  Maybe that shouldn't matter.. Carlton used to be quite flexible when building frames, so maybe mine was a special request for someone who didn't like centrepulls.  Who wouldn't like centrepulls?  That brings me nicely to component choices..

For the brakes, I found a pair of Weinmann Symetric (sic) dual pivot brakes.  Dual pivots were better than the usual side pulls of the time, and better than the centre pulls, so seem like the perfect choice.  Unfortunately, the pair that I bought seem to have been intended for a bike with a plate of metal for a brake bridge, rather than a tube, meaning that the bolt on one of the brakes is incredibly short.  I've got a recessed nut on order that will hopefully solve this problem.

For the chainset, I bought a Nervar crank without really thinking about what I was doing.  The crank is an 80's model, probably from a Peugeot, which looks more modern than I realised.  I'm tempted to swap it for something more in keeping with the frames age, but I'm sticking with it for now.  As it's a French chainset, I had to buy a French bottom bracket.  The tool for fitting it turned out to be crud.  Wiggle advertised it as being good for both cassettes and bottom brackets, but it turned out to not be deep enough for a BB.  I bought a new tool the other day, which will finish the job.

The wheels are 27 inch, with a screw hub.  I bought a 7 speed freewheel for it.

The rear deraileur is a Shimano Arabesque long cage, bought before I realised different cage sizes existed.  The size shouldn't matter - it's just a little bit annoying.  At least it was cheaper than a short cage!  I also bought Arabesque shifters, as I like the retro design.  The front deraileur is a NOS 70s Nervar model.

What else is there?  A GB stem, Raleigh handlebar, Weinmann brake levers..  no seat post as yet.  Oh yes - the seat post!  When measuring the seat tube with a ruler (not the best method for determining seat post size), I noticed a 5mm crack coming off the bottom of the slit (is there a technical name for that?).

Cracked seat post, pre-drilling.  :(

This seems to have been caused by a previous owner over-tightening the seat bolt onto a seat post that was too small.  Internet knowledge said to drill a hole at the end of the crack, to stop it spreading.  I've done that, but now I'm incredibly cautious about what I'm going to do about a seat post.  A trip to a bike shop is probably in order, as apparently they have tools for measuring seat tubes.

When the bike is complete, it should be a nice middle ground between the MTB and the singlespeed.  It'll be interesting to see how it fares.

MTB and back again

For the past week, I've been back on my MTB.  Why?  Well, the front wheel of my singlespeed started making a sort of scraping/grinding noise, and I thought I should probably stay off it while I investigated the cause.  I didn't want it exploding on me, especially now that my journeys home are dark and wet.

It seems that the issue is the spokes.. either a loose spoke, or possibly the noise of the spokes rubbing together where they cross.  It's certainly collected some dirt between them.  I'll clean and oil them, and see if it makes a difference. 

Riding the MTB has been a bit of a revealation - I'd forgotten just how comfy it was!  The big tyres and springy suspension really take the edge out of the crappy road surfaces that I have to endure.  It makes me wonder what it must be like to be riding a full suspension bike, or a pootler with flex stem and suspension seat post.  It must be like riding on a cloud!  That would be awful, though.. I like to get some feedback from the road.  I remember hating powered steering when I first encountered it, because it removed most of the feedback and felt like one of my senses had been removed.  I got over it, though.  :)

It also feels safer to be on the MTB.  Going over potholes or rough surfaces doesn't feel life threatening anymore, allowing me to concentrate more on traffic rather than the road itself, and of course there's the riding position that allows me to see and be seen.  Leaves aren't much of a worry, either, what with the chunky tyres.

My Carlton Cobra singlespeed, at work.

Today, however, I am back on the singlespeed!  The MTB might feel safer, but it is also significantly slower.  It's incredibly annoying to be pedalling flat out, thinking I'm making really good time, then get home 10 minutes later than if I'd used the singlespeed.  Even more annoying is that I never really push myself on the singlespeed, because I spin out too soon.  So a flat out ride on the MTB isn't as quick as a (relatively) sedate ride on the singlespeed.  It just goes to show how much difference tyres, gears, and weight can make!