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tl;dr Is there a way to easily add a smaller chainring to a tourney 7 speed 14-34 freewheel without replacing the hub/wheel

Details: I have a 13" Fuji Women's Adventure 3.0. I've been shopping for a road bike; however, at my short stature (4'8"), options are limited to none. I did find one (Specialized Sirrus Sport step-through) all others were too tall for me to stand over.... but the Sirrus doesn't have the drop handlebars I want, and I don't want to spend that much on a bike and still have to make changes.

The 13" Fuji, although more of a MTB, is the perfect size for me. I'm in the process of adding dropbars and upgrading the appropriate components for compatibility purposes - Shimano Claris 8 x 3 shifters/front derailleur and avid shorty canti brakes. However, it currently has a Tourney 7 speed 14-34T freewheel. Adding the 8 speed shifter opens up the idea of upgrading to 8 speeds, but I'm wondering if there's a way to add something smaller to the existing freehweel - like 11t or smaller - short of upgrading to a freehub and cassette.

  • I'm surprised you can't get a road bike to fit now there are bikes with 24" wheels meant for kids (Giant TCX Espoir for example) – Chris H Oct 24 '17 at 10:44
  • True. I feel like going going from a 26" wheel to a 24" wheel is a bit of a step backwards though. I was hoping to go to a larger wheel like 700c, but I'm settling on the 26" I have until I give up and decide to buy the Sirrus – Kirkyelise Oct 24 '17 at 17:25
  • Generally speaking, rebuilding a MTB or hybrid with dropbars gets rather expensive unless you can salvage useful components off another bike. – Criggie Oct 24 '17 at 21:18
  • Do consider joining the Bicycles Chat when you get a bit more reputation on SE - we can talk more specific examples there. Specific product recommendations are considered off-topic in Q&A. – Criggie Oct 24 '17 at 21:20
  • Yes. I'm pretty sure I've spent more money on parts than I spent on the bike brand new 7 years ago, but at least it's fun! – Kirkyelise Nov 2 '17 at 14:40
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Good question. The specific answer, to whether you can add a gear to your existing freewheel, unfortunately is not really. Freewheels used to be more configurable than they are now. Freewheels now don't have individual cogs available, and even if they did and also even if there were a way of getting 8 of them on to a freewheel body made for 7, Tourney TZ-31 and similar 14-34 7spd freewheels don't have physical clearance for anything much smaller than 14 anyway. Modern freewheels are not very hackable.

8-speed freewheels do exist. Because 7 speed cog spacing is 5mm and 8 is 4.8, and 7*5=35 and 8*4.8=38.4, they have to be longer than 7-speed freewheels, just like 8 speed freehub bodies are longer than 7. Wheels can be re-dished and re-spaced to accommodate 8, but doing so leaves you with a very highly dished wheel, more so than if it were an 8-speed freewheel hub because the flange-to-flange spacing will be greater. So buying an 8-speed freewheel and converting the existing wheel is not a good solution. If you want more range, 11-34 7-speed freewheels exist and may be a good option. Shimano stopped making them and they've become somewhat sought after and hard to find, but they're out there.

  • I suspect OP wants to get more high gears, so a larger front chainring might be a halfway improvement that doesn't cost excessive amounts. – Criggie Oct 25 '17 at 0:06
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    Yes, I'm actually now looking at eventually replacing the crankset to larger chainrings and shorter cranks to accommodate my short legs... But that probably won't be this year, as it would probably be another big project of upgrading to freehub (replacing both front and rear wheels), a new chain, and a new rear derailleur. For now, I just have to keep reminding myself that I don't have the leg strength to use the higher gears without significantly dropping my cadence. – Kirkyelise Nov 2 '17 at 14:37
  • @Kirkyelise Front wheel does not need changing at all. Perhaps aim to do this when you've worn out the current chain and cassette, that way you're saving a bit of money by combining the two replacements. – Criggie Nov 3 '17 at 1:42
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Your 7 speed freewheel is old tech and is a bit of an orphan too - adding cogs increased the unsupported length of axle leading to more bent axles. 7 speed freewheel is really beyond the limit for most riders, and yours has probably survived this long because of your reduced load.

For the cheapest - you can get a freewheel that has a 13 tooth small cog. For example https://harriscyclery.net/product/shimano-13-28-thread-on-7-speed-freewheel-2694.htm at $23 USD. You'll want a new chain too.

However that only gives you 1/14th higher gearing AND you loose some climbing gear too dropping from 34 to 28 tooth.

There is a "mega7" 7 speed freewheel which ranges from 11 to 34 tooth, but good luck finding one. http://www.sheldonbrown.com/mega7/ shows 11-13-15-18-21-24-34 as the tooth counts, and looks like this:

http://www.sheldonbrown.com/mega7/mega7freeewheel06.jpg

They're long discontinued, so Ebay would be the best source.


On the other hand, you're wanting to get a better bike then its time to consider stepping up to exactly what you want.

A bike build starts with the frame, wheels and bars. They dictate everything that comes afterwards.

Instead of a 26" wheel look at a 650b road wheel size, and a road frame that is a suitable size for your leg length.

You're as far to the short side of "average" as I am to the "tall" side of average, so I know your frustration on sizing, but from the opposite side. You have the advantage of fitting onto a young-adult's frame which doesn't exist on my end of the sizing spectrum.

I'm not making a product recommendation here, but as an indicative example something like https://www.specialized.com/us/en/kids/bikes/allezjunior/128824 may be a good fit for you.

From spec link above Its a 650 wheel, and has 8 speeds. You're unlikely to find 10 or 11 speed bikes in the smaller size wheels because there's just that much less room for the rest of the wheel's hub. Has the same dual-pivot brakes a larger road bike would have, and the cassette is 11-32 with 8 gears and proper road bike brifters.

In terms of gearing, 34/46 with 11-32 on 650 wheels gives you a lowest gear of 26.2 gear-inches and a high gear of 103.3 gear-inches.
That's pretty jolly close to my 700c wheel triple crank road bike with 24.5 gear inches to 101.1 gear inches.

IE its a full-on road bike with all the road bike features, and not a modged-about MTB.

I'd strongly stick with a decent brand name kids bike, because cheaper bikes are slightly more likely to be BSOs where the kid grows out of them rather than wearing them out.


Your final option is to replace the rear wheel hub with a 8/9 speed cassette-based hub. Shopping list of parts

  • New hub with a cassette freehub. Number of spokeholes has to match existing rim.
  • Matching cassette, 11-34 tooth 8 or 9 cogs.
  • New right-hand shifter with matching 8 or 9 gears.
  • New chain of 8/9 gears to match
  • New gear cable inner and outers - they're cheap and may as well do it now.

You may require

  • New rear derailleur, if your existing one can't move quite far enough to get to the top and bottom cogs.
  • New spokes if the old hub and new hub are different dimensions
  • New rim if the rear hub has a different number of spoke holes etc.

It is frequently cheaper to buy a new wheel complete than to try and rebuild an old rim onto a new hub. An 8/9 speed 26" MTB wheel should be relatively common to buy complete.

You should be able to re-use

  • Existing chainrings provided newer thinner chain fits
  • Front derailler, but thinner chain will shift a bit worse. You may need to overshift and then trim back, or maybe compress the FD cage a bit for the thinner chain.

Downside, this will leave you with a MTB frame with more gears, still heavier than a road bike. Plus braking performance may suffer using the MTB wheel brakes with dropbar brake levers. Really, not recommended for both price and performance reasons.

  • Most of these replacements are done. I'd definitely just upgrade the wheels over rebuilding the wheel. It has 8x3 Shimano Claris brifters with a Shimano Claris FD. Interesting you should mention difficulty with the FD though - I can't seem to get it to shift for anything. I reused some cable housing, so I'm going to try recabling just the FD (again) in case some of the housing I used was bad. – Kirkyelise Nov 2 '17 at 14:45
  • A new crankset is also on my wish list – Kirkyelise Nov 2 '17 at 14:46

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