Chainline (again) a cautionary tale...
GarethPJ
Posts: 295
Just had a long ranty email from a friend. He bought an old road bike recently with horizontal dropouts, the intention was to convert it to fixed wheel. His next purchase from ebay was a "track" wheel from ebay, spaced at 120mm it was ideal for his frame. So the bike was stripped of it's geary gubbins, cleaned up, treated to new tyres, new contact points and generally pampered. It then sat in the shed over christmas, complete with the exception of a chainset.
Today our hero took a trip to his LBS. They are mostly mountainbike based and track bits aren't something they stock. However one thing on the shelf was a single speed specific crankset. So he bought that, a bottom bracket to suit and a 44T ring. (Some of you will know where this is going now, as did I when I read his email.)
Total bill was about as much as the rest of the bike had cost so far, but he was eager to get out on the road. His intention was to spend this evening removing the old BB and bolting on his new goodies, so he could ride it tomorrow. All went well until he came to fit the chain, at which point he noticed the chain line was a mile out. After a bit of pointless fiddling he realised there was nothing he could do. A shorter BB, if such a short one could be had, would bring the crank arms perilously close to the stays (and I suspect into contact with the BB cups). And so he sent me his ranty email, the main thrust being that his LBS had sold him a pup.
Now we all know that old single speed/hub gear/track chainline is about 40-42mm. We also know that the "standard" for single speed MTB's is about 10mm more don't we? He clearly didn't.
He didn't explain what he wanted the gear for, just selected it and paid up. So the shop are in no way to blame. Hopefully (for him) he's been gentle enough with both parts and packaging that he can get away with a refund. Hopefully (for me) he hasn't and I'm in for some bargain new parts for the singlespeed tourer I'm building.
Anyway. Just in case you didn't know the difference, you do now.
Today our hero took a trip to his LBS. They are mostly mountainbike based and track bits aren't something they stock. However one thing on the shelf was a single speed specific crankset. So he bought that, a bottom bracket to suit and a 44T ring. (Some of you will know where this is going now, as did I when I read his email.)
Total bill was about as much as the rest of the bike had cost so far, but he was eager to get out on the road. His intention was to spend this evening removing the old BB and bolting on his new goodies, so he could ride it tomorrow. All went well until he came to fit the chain, at which point he noticed the chain line was a mile out. After a bit of pointless fiddling he realised there was nothing he could do. A shorter BB, if such a short one could be had, would bring the crank arms perilously close to the stays (and I suspect into contact with the BB cups). And so he sent me his ranty email, the main thrust being that his LBS had sold him a pup.
Now we all know that old single speed/hub gear/track chainline is about 40-42mm. We also know that the "standard" for single speed MTB's is about 10mm more don't we? He clearly didn't.
He didn't explain what he wanted the gear for, just selected it and paid up. So the shop are in no way to blame. Hopefully (for him) he's been gentle enough with both parts and packaging that he can get away with a refund. Hopefully (for me) he hasn't and I'm in for some bargain new parts for the singlespeed tourer I'm building.
Anyway. Just in case you didn't know the difference, you do now.
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Comments
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I didn't know that specifically but am aware that different bikes types have variations. When I go to my lbs I tell them what type of thing I want to buy and how I intend to use it, then if there's anything I need to know they tell me.Bikes, saddles and stuff
http://www.flickr.com/photos/21720915@N03/
More stuff:
http://www.flickr.com/photos/65587945@N00/
Gears - Obscuring the goodness of singlespeed0 -
Did not his original purchase come with cranks - or was it frame-only?d.j.
"Cancel my subscription to the resurrection."0 -
meagain wrote:Did not his original purchase come with cranks - or was it frame-only?
Yes it came with a double, and a well worn cup and cone BB. My approach woulh have been to convert the chainset to single ring and then work out the correct length of BB to suit. I'v done it many times and it's obviously much cheaper. Now if only he'd asked my advice before his trip to the shop rather than afterwards.0
