single speed lesson
Since finishing school I haven’t been commuting daily on my Marin Hamilton 29er single speed bike. I finally decided that the time was right to slap on my knobbies and hit the trail! Unfortunately, the stock gearing on the Hamilton is set up for the street so it was a bit more complicated than swapping out the tires.While performing maintenance on the Hamilton in the past I discovered that the freewheel is not the typical single speed BMX style set-up. Instead, the Hamilton features a mini Shimano-style freehub on one side and a standard fixed gear + lock ring set-up on the other:
This created a challenge because the only single speed cassette style sprockets I have been able to find come with single speed conversion kits generally designed for street bikes. So, I stopped by the local bike shop and dug through a few boxes of old cassettes to find a 19T Shimano style sprocket. I then dug out an old chain from my road bike and my knobbies and fitted everything up.
The new set-up seemed to work fine during the test ride around the apartment complex. The gearing felt a little high given the mass of the 2.3″ wide 29er tires (a 20T sprocket would likely be a better companion to the 33T chainring) but I figured it was good enough for me to give it a trail test.
It has been at least 16 years since I last rode the Bratram Trail. Back when I first started college I used to ride the Bartram 2-3 times a week. This morning I woke up at dawn, loaded up the Hamilton and headed out for the trail. The first section of the trail is a technical (sand, roots, ruts, tight turns) downhill followed by a short climb up to a long rolling section. I floated downhill the first 300 yards on my enormous knobbies and was feeling pretty good. Then, I hit the first climb and with the first application of significant power POP! The next thing I know I’m dislodging my stem from my gut:
It seems my thigh took the brunt of the impact:
I assumed my old chain had broken so I was rather surprised to find the chain had simply come off the rear sprocket. I was even more surprised when I was able to easily spin it back onto the rear gear. I was further surprised that my chain was perfectly tensioned once I got it back in place (my second assumption was that the rear wheel had shifted in the drop outs, loosening the chain).
At first I thought maybe it was just a fluke but after 3 more derailments in the next 100′ I gave up and walked the 1/4 mile back to the parking lot. The lesson learned here is that the sprocket and chain combination I was using was designed for a multi-gear set-up and not single speed use. They are designed to release the chain during shifting instead of holding onto it at all costs. The chain line is pretty much perfect so I guess the torque of trail riding combined with a little sand was enough to “shift” the chain off the sprocket. Single speed bikes need single speed parts. Lesson learned.
Back to the drawing board.
UPDATE: I found a 20T single speed sprocket for $4 at JensonUSA so I went a head and ordered it and a new $10 single speed chain. The parts just arrived so I may get to try this all again tomorrow!
BTW, that bruise on my thigh has developed nicely over the week, showing that I took a harder hit than I originally thought…
UPDATE II: All mounted up and ready to ride! (Note leaf bits on chain from vigorous test ride):
September 27th, 2009 at 9:58 pm
What was the front and rear gear cog numbers when you first bought the bike? Do they provide the other gears?
September 28th, 2009 at 7:26 am
Michael, the original gearing that came with my Hamilton was 33×13T. The 2009 model features 33×15T gearing for a bit more relaxed ride. Keep in mind that the Hamilton isn’t intended to be a mountain bike, more of a city bike. I’m just playing around with it. I figure at only $400 if I break it on the trails then that’s a good reason to invest in a real off-roader ;-)
July 31st, 2010 at 5:53 pm
I am looking at the 29er and came across your post here. How do you like it? Honestly? I read where it is easy on the back, is this true? I broke my tail bone in 4 places a few years back and hasn’t been the same since. Have you road it again yet with the knobbies on? I will mainly ride it around town, but we have small trails here in Ponca City,OK lol. We also have a large lake I would love to ride around with some mixed pavement and dirt. How does the flip-flop hub work? Do you just flip a lever or do you actually have to dis-assembly and turn around? Thanks for your time, I really appreciate it.
Ben Duke
August 2nd, 2010 at 7:11 pm
Ben,
The 29er is definitely more comfortable than any hardtail 26″ mountain bike I have ridden. To be fair, I have never ridden a modern full suspension bike so my comparison is rather limited.
Unfortunately, (or fortunately, depending on how you look at it) I got a new job and had to move right after I wrote this post and as it turns out, off roading was a one-time event. That being said, I have ridden the bike quite a bit around town with the stock Continental “city’ tires and i think they would be fine for the occasional hard pack trail as long as you aren’t trying to go all gonzo and stuff.
The flip-flop hub has a mini freehub on one side and a standard fixed gear on the other side. To switch you have to use a wrench to release the axle bolts, remove the wheel and re-install in the opposite direction. If you run the same size sprockets on either side the transition is pretty straight forward. For me, I was running a 20T on the freehub and a 15T fixed and there wasn’t enough adjustment room in the dropouts to make both work without adding and removing chain links, adjusting brakes, etc. Needless to say, I didn’t find much of a use for the fixed gear side.
Hope this helps!
November 4th, 2011 at 6:48 pm
2.3 inch wide tires is impressive. I was looking at 2009/10 version at my local shop just a minute ago and the did not think a 2.0 would fit. I was skeptical as I’d seen you photo before and some others with some “big apple” tires. Do you think a 2.0 and a set of fenders would fit in there?
January 8th, 2012 at 9:33 pm
I have a 2009 Marin Hamilton too. I was wandering what type of tires you have in the back. I see that you said you run a 2.3 tire size, but wandering what kinds. Check out my link I put on here and you can see what I did with mine. I changed out the decals, bars, brakes and some other stuff. But yours looks great!
January 8th, 2012 at 9:40 pm
Also I thought I would let you know about the cool decal on the seat post tube…The owner’s son-in-law died and was hawaiian. When he died he wanted to put the that decal on the bike. The decal was one of his son-in-laws tattoos and also it is a hawaiian warrior helmet. Just thought I would let you know.
February 15th, 2012 at 1:49 pm
Thanks, Ben. Interesting fact!
February 15th, 2012 at 1:51 pm
Sorry, I don’t have the knobbies anymore. I think they were WTBs but I’m not sure. I have converted the bike back to street/commuter use where it really shines. I really don’t think the Hamilton is up to heavy duty off road use. Probably better off buying a bike already set up for that if that’s your goal.
February 16th, 2012 at 12:51 pm
2.0, sure. Fenders? Don’t know. Depends on the design, I guess.