My girlfriend's started having some knee pain after commuting for about a year on the bike I got her (10 mi round trip or so). Her bike has a 39/53 road crankset and 14-24 7-speed freewheel. I'd like to figure out the easiest way to lower the gears for her, while keeping the 7-speed bar-end shifters.
Does anyone know where I can buy a 7-speed freewheel in something like 14-34? Happily I have a long-cage SunTour derailer lying around, which would make that easy. Or I was thinking of going to a biopace triple I have... but that seems like more of a pain since I'd have to find a triple front derailer that fits the bike. Anyone have advice for the best way to get a bunch of low gears?
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You could also keep your current freewheel and install smaller rings.
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You can get Shimano 7spd freewheels with 28t.
Get rid of the racing double and fit either a compact double or a triple with a max 50t ring. I use a 28/38/48 with a 13/28 freewheel and never have issues with the top gearing. I'm not in a race so can roll down a big hill but I can also haul my groceries up steep inclines.
Also, make sure that the crank is a suitable length for your GF.
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It's not the gearing on the bike that's the issue, it's the gears she's choosing that's the problem. There's nothing you can do on the bike to change that. She needs to learn to use easier gears and spin more. Unless you take away her big-ring, there's no way you can enforce that.
Does she have toe-clips on the bike? Riding without toe-clips tends to cause mashing motions with very high peak-loads on the knees 1/3rd of the way into the downstroke. WIth toe-clips, she can spin easier gears, thus requiring lower muscle-force for the same speeds. This also lower loads overall on her knees as well.
I can build you a 7-speed Suntour freewheel easily. Are the bar-ends Accushift or friction?
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Shouldn't be too hard.
Shimano currently produces 11/34 and 13/34 megarange freewheels. The 34 is really a bail-out gear because the gear progression jumps from 24 to 34.
(锕侊箒)~~~~---------------------------------------------------------------------- Originally Posted by DannoXYZ
It's not the gearing on the bike that's the issue, it's the gears she's choosing that's the problem. There's nothing you can do on the bike to change that. She needs to learn to use easier gears and spin more. Unless you take away her big-ring, there's no way you can enforce that.
Sort of true. What she needs is a wider choice of gears within the range that's right for her. Here's my example. I have an 8 speed cassette that goes 12-13-15-17-19-21-23-26. If I use the 12,13, or 15 cog with either my 42 or 52 ring, I'm either mashing or going much faster than I can sustain. Yet, those are my only gears that are close and give me the ability to make small adjustments according the wind or grade of the road (it's mostly flat where I live) and keep my cadence right. What I've longed for is a 13-21 cassette that gives me more gear choices between 15 and 19. In other words, I need a 16 and 18 cog. Unfortunately, the gear choices in an 8 speed are pretty limited these days.
One thing he could do is go to Sheldon Brown's gear calculator and print out a little cheat sheet that tells her what gears and speeds she needs to go in order to have a given cadence. Or he could buy her a computer that gives cadence and put that on her bike. That might help her a lot.
Originally Posted by DannoXYZ
Does she have toe-clips on the bike? Riding without toe-clips tends to cause mashing motions with very high peak-loads on the knees 1/3rd of the way into the downstroke. WIth toe-clips, she can spin easier gears, thus requiring lower muscle-force for the same speeds. This also lower loads overall on her knees as well.
My arthritic knee has practically been cured by using clipless pedals. If it's bothering me at all, I go for a ride and my knee feels better afterwards. Toe clips are OK, but to get any biomechanical benefit they have to be cinched really tight and that can be rather unsafe, especially commuting. Clipless is the way to go if one has knee problems. I even told my ortho that he should recommend them to his other kneed patients, they're that good.
Originally Posted by DannoXYZ
It's not the gearing on the bike that's the issue, it's the gears she's choosing that's the problem. There's nothing you can do on the bike to change that. She needs to learn to use easier gears and spin more. Unless you take away her big-ring, there's no way you can enforce that.