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View More: → Rear Gearing Ultimate Gearing Modifications For Your TrikeAshley Guy - 07/01/2007 By Ashley Guy of UtahTrikes.com Schlumpf HSD ![]() Our next entry in the front-end category is the Schlumpf High Speed Drive. I really like this drive a lot. Essentially, it eliminates the entire set of chainrings, front derailleur, and shifter and replaces them with a new single chainring with overdrive. The chainring on the standard Schlumpf HSD is a 27-tooth sprocket. Inside of the drive there are internal gears which, when activated, make the chainring turn 2.5 times for each pedal rotation. This has the effect of giving you a virtual 2-chainring setup with a 27T on the low side and a 67.5T on the high end. Oh yeah, try finding a 67.5T chainring out there! Not gonna happen. So lets plug in our numbers and see what we get: 20-inch tire w/11-34 Cassette and 24/67.5 Schlumpf HSD = 16-123 GI Wow, so we even get a slightly lower end, and our high-end gearing is looking pretty nice. Lets check out our speeds again. With an 80RPM cadence we would see an increase of speed from 23MPH (Stock 53T) to 29MPH (67.5T Schlumpf). At 120RPM cadence we would see a difference of 34MPH (Stock 53T) to 44MPH (67.5T Schlumpf). Wow, with those numbers I think we could stop and keep most people happy, but there still might be some hills you cant pedal down, so let's keep going. Cost: $499 plus assembly Pros: Elegant solution, replaces entire front derailleur and chain rings. Eliminates possibility of cross chaining. Small 27T chainring promotes nice chainline. Easy to swap cranks for different sizes. Gives even lower end gearing. Can be shifted when stopped. Cons: Needs to be installed with special tools. Internal gears are only 95% efficient. Front End summary So, in the front we have a couple of solutions available. Going with a 56T chainring is easy enough if you have a front derailleur that can handle it. If you are riding near your limit with the 53T chainring, then getting the extra 2MPH from the larger chainring might be worth it to you. The Schlumpf High Speed Drive provides a very nice gear range and eliminates the need for some other components. It is fairly costly though and does provide a slight loss in efficiency. The nice thing about these Front End options is that they CAN be combined with other rear end options. Rear End Gearing Solutions The stock 11-34 MegaRange cassette found on most stock trikes gives us 8 or 9 gears (depending on the cassette) and a pretty good range. In order to get a higher top-end gearing we need to change the gearing more than what the 11T sprocket can do for us. The problem is that the smallest sprocket that will fit on the standard Shimano-style hub is the 11-tooth sprocket. Internal Hubs - Shimano Nexus 8 Ive been a big fan of internal hubs for a while, particularly the Shimano Nexus 8, so that is the one Ill be talking about. Internal hubs have just one sprocket for the chain and different gears internally. Each gear, when selected, rotates the wheel by a factor of the connected sprocket. The smaller the connected sprocket, the higher your top-end gearing will be. The smallest sized sprocket for the hub that I could find required some modification and is a 17T. Lets crunch the numbers: 20-inch tire w/17T Nexus 8 Hub and 24/42/53 Chainrings = 15-100 GI Here we see an even lower bottom end, and just a slightly higher top end. With an 80RPM cadence we would see an increase of speed from 23MPH (Stock 11T) to 24MPH (17T Nexus 8). At 120RPM cadence we would see a difference of 34MPH (Stock 11T) to 36MPH (17T Nexus 8). If we could find or modify or find an even smaller sprocket like a 16T our top end would get even higher. 20-inch tire w/16T Nexus 8 Hub and 24/42/53 Chainrings = 16-107 GI 20-inch tire w/15T Nexus 8 Hub and 24/42/53 Chainrings = 17-114 GI Cost: Hub, wheel, shifter, and idler/tensioner is $500-$600. Pros: Shift at anytime rolling or stopped. Easy to play with different ratios. Cons: Need a whole new wheel. Need to run an addition idler or modified derailleur to take up chain slack. Need to change shifter. May need to modify mount to get it in. May need to modify the sprocket. Only 80-95% efficient compared to derailleur. While it appears that there are more cons than pros, I still love this hub. Being able to shift at any time, while not a focal point of this article, is a huge benefit. The gear range is good and can be moved up or down to suit your own preference by just changing a single rear sprocket. Shimano Capreo The Shimano Capreo system is relatively new, and was designed especially for small-wheeled bikes like folders and recumbents. Essentially they made a new hub that works with a modified-type cassette and has smaller gears. The standard setup has a nine-speed 9-26T cassette. The smaller 9T sprocket will give us a higher top end so lets see what the calculator says: 20-inch tire w/9-26 Capreo Hub and 24/42/53 Chainrings = 18 -118 GI Those numbers are pretty good. With an 80RPM cadence we would see an increase of speed from 23MPH (11T) to 28MPH (9T). At 120RPM cadence we would see a difference of 34MPH (11T) to 42MPH (9T). My favorite thing about this setup is that all the modifications are made to the wheel, and not the trike itself. You can just pop the wheel off and replace it with the stock one if needed. Cost: Hub, cassette, wheel w/assembly about $200-$300 depending on the wheel. Pros: Does not require a different derailleur if you have a 9-speed. Cons: Only works with 9-speed derailleurs. Requires new wheel. Currently hard to find in the US, so you may have to import it. Ultimate Gearing While there may be other solutions available that others have tried, I only wanted to talk about things that I have tried. I am currently working on one more exciting option and that is mounting a 26-inch wheel on the back of a TerraTrike. More details on that to come soon. In the meantime, we can get even better results than those mentioned above when we combine the front-end modifications with the rear-end solutions. I personally have trikes set up with two combinations as detailed below. All Internal Gears My main commuter trike is a Cruiser equipped with both the Schlumpf HSD and the Shimano Nexus 8 Hub. This completely eliminated derailleurs for me and with a nifty idler mount from TerraCycle I dont even need a chain tensioner. I can shift at any point, even while stopped or coasting, which makes riding in traffic much easier. The Shimano Hub is most efficient in 5th gear because none of its inner gears are used at that position and the sprocket is locked to the hub. I played around with different sprockets and found that a modified 17T was best for me. So crunching the numbers I get: 20-inch tire w/17T Nexus 8 Hub and 27/67.5 Schlumpf = 17-128 GI Cost: About $900 Pros: Only one shifter. Can shift at anytime. Great gear range. Great chainline. No derailleurs. Cons: Less efficient due to all the internal gears. Expensive Requires major modifications. Slightly heavier than stock gearing. While being less efficient, this combination really gives me the high gearing I like for going downhill, while still giving me the low end to climb any hill. There are certain gears where the two internal gears vibrate together and I hear a rumble sound, but overall I dont notice that it is terribly inefficient. Bigger Up Front/Smaller In Back My fast racing trike is a WizWheelz Race running a 56T chainring up front and the Shimano Capreo gears in back. While I dont get quite the gear range that I have on my Cruiser, it is a marked improvement over the stock gearing. Being a much lighter trike (and not loaded with as much stuff) I dont need the low-end gears because it is much easier to go up hills. Also, because it is a lighter trike gravity does not help me as much going down hills. I still spin out at about 47MPH with this set up, but overall it is much more efficient and WAY cheaper than the Schlumpf/Nexus combination. Here are the numbers: 20-inch tire w/9-26 Capreo Hub and 24/42/56 Chainrings = 18 -124 GI Cost: About $270 Pros: Cheapest solution to raising your gears. Uses all stock derailleurs. Cons: Gear range still not quite high enough. Until next time Once I have the results of the big wheel modification Ill let you know! |
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