Which KHS model is best for a FS ebike?

[Jerome Daoust]

I started 2010 by catching the Endless-Sphere flu, where I now have the urge to build myself an ebike…

I can get a good price on a KHS model, but I don’t know which one to choose, for making a FS (Full Suspension) ebike.

Should I avoid their downhill and freeride models, because of their geometry adapted to riding down a slope?
DH200. 8.5” rear and 203 mm front travel. $5000 MSRP.
Lucky 7. 7.3” rear and 180 mm front travel. $2500 MSRP.
Velvet. 6” rear and 160 mm front travel. $2000 MSRP.

Amongst their XC Trail models, these seems to represent key models:
XCT 555. 5” rear and 140 mm front travel. $2000 MSRP.
XCT 525. 5” rear and 130 mm front travel. $1400 MSRP.
XC 204. 4.2” rear and 100 mm front travel. $1100 MSRP.
XC 104. 4.2” rear and 100 mm front travel. $800 MSRP.

Any bad experiences with electrifying a KHS bike? I see that Hi-Power Cycles is using them.

Thanks and good rides in 2010,
Jerome

Related topic: Tidal Force: Which KHS model is best for a FS ebike?

 

[Jerome Daoust]

A good question for myself is: How much suspension travel do I want? I can answer from with past experiences…

Ultra Motors / A2B Metro (rode one today, again): 30 mm rear, 80 mm front. Insufficient in rear, Marginal in front.
Cadillac AM2.4: 4-6" adjustable rear, 100 mm front (Rock Shox Reba SL). Felt good.
Optibike 800Li: TBD mm rear (Fox Float RP23 Shock), 140-150 mm front (Fox 32 Talas RLC Fork). Felt very good.

So 4” or 100 mm seems like a minimum and 5” or 130 mm would be appropriate for my riding.
If that’s the case, I should probably choose between these 3 models:
XCT 555: 5” rear, 140 mm front travel.
XCT 535: 5” rear, 130 mm front travel.
XCT 525: 5” rear, 130 mm front travel.

Today I was allowed to sit on (but not ride) a customer’s XCT 535 that was in for a flat repair. Suspension felt good (soft) when rear shock pressure was temporarily adjusted for me. Front fork felt good with ample travel, but the salesperson said there was no air pressure adjustment possible, while online description just says “RS Tora 302 Solo air W/Alloy steerer Lock Out 130 mm”.

Overall I feel that 5” travel is right for me, just wondering which of those 3 models to choose. Is there any significant value in getting the upgraded components of the 555 or 535, over the least expensive 525?

Thank you, Jerome.

 

[docnjoj]

The general rule of suspension travel is "More is better". Mercedes and many autocross bikes use it and if you can adjust jounce and rebound then more is definitely better. I have 4-5 inches at the wheels of my trike and the difference is remarkable compared to a Walmart type ususpension! Good luck in your choice!
otherDoc

 

[mabman]

The most expensive Hi-Power bike uses the 555 but the frames for the 25, 35 and 55 are probably the same thing with the difference in pricing at the component level. I would suggest just getting the 525 because of this. Use the money you save to get the best motor and battery you can afford to get the best range and power which will mean more on an electric bike than the more costly componentry in the long run? You will if anything need a bigger chainring on there :wink:

I tried to use one of those seat tube racks (as shown on the H-P bikes) once for a battery and had no luck with it whatsoever, perhaps they are making them stronger now but still can't see how they keep them from going sideways which was the main problem I had with mine?

 

[kfong]

Battery placement is also a big issue. When I looked for a bike, I picked up one with the most area in the triangle as possible for my batteries. I don't like all the weight in back since handling becomes tail heavy. With the newer A123 duct tape cells, it's much easier to find room for them, but if you are going with konions or A123 round cells. It becomes very difficult to find room.

 

[Jerome Daoust]

Thanks guys.

At the point, I'm giving up in fitting batteries inside the frame, and will just use a rear seatpost rack. In the years to come, this method will become more appealing as weight of batteries comes down.

...the frames for the 525, 535 and 555 are probably the same thing with the difference in pricing at the component level. I would suggest just getting the 525 because of this. Use the money you save to get the best motor and battery you can afford to get the best range and power which will mean more on an electric bike than the more costly componentry in the long run? You will if anything need a bigger chainring on there

Yes, the salesperson I saw today said they were the same frame, and the price difference is for the other components. His recommendations was that where manufacturers can save to reduce the price was typically on the suspension components, which would be going against my goal of better suspension. Good salesman or honesty guy? Need to see those bikes side by side to have a better opinion.
In any case, the amount I spend on the bike will not change my plan for the motor and battery.
A Schlumpf drive could make sense if I see I can't keep up at speed. Dennis seems to like his.

I tried to use one of those seat tube racks (as shown on the H-P bikes) once for a battery and had no luck with it whatsoever, perhaps they are making them stronger now but still can't see how they keep them from going sideways which was the main problem I had with mine?

I hear about riders using set screws to prevent them from rotating about the seatpost, or preventing the seatpost from rotating in the frame. May not be elegant, but another idea would be to extend an arm forward from the rack beam that attaches to the frame ahead of the seatpost.

I was starting to consider the Velvet because it is the same price as the XTC 555, yet offers an extra inch of suspension. But the Velvet has a rear thru-axle (not a drop out) so axle needs to be pulled through to remove the rear wheel (see attached picture). Same problem for the Lucky 7 and the DH200 has a front thru-axle and possibly also at the rear. So no DH or freestyle models it seems, and the XTC 555 now becomes the high-end model considered.

 

[Jerome Daoust]

No surprise, the attached chart (from KHS website) confirms that the frames are the same for the XCT 525, 535 and 555.

Seat height over the ground: I'm 5'10" (1.78 m), weight 172 lb (79 kg) and the Medium-sized XTC 535 I sat on today allowed me to have both feet flat on ground with knees slighly bent, when the seat was at its lowest. So even with the seat raised 2" (5 cm) for a seatpost rack clamp, I should still either have, or be close to having, both feet flat on the ground.

 

[dogman dan]

Interesting, I was just looking at the khs xtc myself. I've been riding around on the cheap wallbike with about 40 mm of travel front and back for 5000 miles, and am now going to upgrade, but decided on more ping battery rather than the khs. I'll be using a better frame mongoose I already have, and put some upgrades on it so I'll have a 100 mm travel front and back. This won't be enough for serious trail riding, but will be good enough for swerving into the dirt shoulder when "bud light" gets too close in his pickup truck.

Anyway, I'd say buy as much frame as you can be comfy with. For me that's more the standover height, since FS tends to have the pedals way off the ground, but you do want to be comfy straddling the frame. That way, even if you don't put battery there you have room for other stuff, like a huge 72v controller or something. The KHS XTC had the kind of frame I consider a good choice with the shock placement.

As for the suspension, I was looking pretty much in the cross country frames, usually having 4 or at most 5 inches of travel for a new commuter. My giant OS2 has 5 inch rear travel, and to ride it on the street, you have to preload the crap out of it, or you'll bob yourself silly pedaling in higher gears. So 4 inch travel rear shocks are quite enough. For dirt riding, it would be another story, Either a full on DH bike or a Freeride bike with lots of suspension travel would be desirable for serious dirt riding with lots of extra motor and battery weight. Paying a ton of money for weight upgrades on the higher end bikes in a model line makes no sense to me, but going up to the level where the fork has full adjustability instead of just preload makes some sense.

 

[mabman]

At your height and weight I doubt that the upgrade in suspension between models would be noticeable if you plan to use the bike primarily on the street? Even the "lesser" shocks are still pretty good units but if you have the money to spend then by all means go ahead and do so.

I also have used the Schlumpf drives now for years. They are very stout and I highly recommend them. For your purposes the high speed drive would be what you want. It does take a special tool which chamfers the bb shell to install but they are around or it can be done by a machinist also.

 

[billvon]

I think way too much emphasis gets placed on suspension travel - especially with hubmotors, which greatly increase your unsprung weight anyway. Lots o travel may help on bad roads, but even with a hardtail I haven't had problems on anything but bad roads above about 25mph.

If it were me I'd concentrate on the stuff you'll use everyday. Get a good frame sized both for you and for carrying batteries low on the frame (above the crank or in front of the down tube.) Disk brakes are a must at the speeds/weights most ebikers ride at; front disk at a minimum. A good component group will keep you more interested in pedaling, which will pay benefits in range, top speed and fitness. Getting a larger front chainring will help with maintaining a reasonable cadence at higher speeds. A more beefy steel frame will allow easier modification (you can weld to it, drill it out, clamp to it etc) and a longer wheelbase will allow more flexibility in mounting _and_ cushion the ride.

In many ways I think the Surly Big Dummy with a good (stiff) front fork and a moderately good component group is the ultimate platform for an ebike. It's a big steel bike that's resilient, has a _very_ long wheelbase, can carry anything, is way overdesigned and will last forever.

 

[dogman dan]

Bavillion hasn't crushed any disks yet. I need suspension for riding more than 10 miles. When I was young, I needed no suspension, but then it didn't exist yet either. But he's right, all you need is enough suspension to meet your needs, for me 80 mm travel is enough for the streets I ride. 5000 miles with 40 mm wasn't that bad, but when you bottom out, wham!

 

[docnjoj]

Roger that, dogman! Especially with a recumbent, you cant post, so your rear suspension is the only thing between your back and a very hard place. The more travel coupled with good damping, the better!
otherDoc

 

[Jerome Daoust]

Thanks guys. I see a trend in the replies that the more suspension travel and quality, the better. On the TF forum another experienced rider (and bike mechanic) goes in the same sense:

Mike Knowles, 2010/1/4[/url]"]555 for me the shocks are a bit plusher.

So my choice at the moment is the KHS XTC 555. Just need to feel confident about the size: S, M, L. Most likely the M for my height of 5'10" (1.78 m) and weight of 172 lb (79 kg). I like to have my feet flat on the ground while on the seat at its lowest. I only pedal lightly, but will get off the seat on occasions to get up a steep short hill. Most likely the Medium would be appropriate, since it shares the same frame as the XTC 535 I sat on last Sunday, and that one felt right.

 

[patrickza]

Battery placement is also a big issue. When I looked for a bike, I picked up one with the most area in the triangle as possible for my batteries. I don't like all the weight in back since handling becomes tail heavy. With the newer A123 duct tape cells, it's much easier to find room for them, but if you are going with konions or A123 round cells. It becomes very difficult to find room.

I agree with that completely. In fact since I built my bike I keep looking at other full suspension bikes and either say "ooh look at the size triangle on that machine" or "too small, I don't like it". I could swear I was speaking about breasts

 

[kfong]

Yeah, I barely got my packs into the frame of the triangle. See my BMC build. I had to change from A123’s to Konions for the higher density. It would have been nice to use Lipo packs, but I have bad experiences using them from fires and longevity to want to rely on them for more than a year. If you ever see a lipo pack go off, it would ruin your day. This is from a few years in the RC hobby. When I get done with the new bike, the packs will be well integrated into the frame and will not interfere with pedaling, another important issue. I see some setups where pedaling is just about impossible with the way the packs are placed. Being stuck out in the woods and pushing a dead ebike around is not something you ever want to do.

There are newer LifePo4 duck tape packs now. I will be following those, since they are 15 and 20ahr packs. Those would be my next packs if I decide to change out the konions. This won’t happen for a few years.

On my Cyclone build, I have just 3 dewalt pack in the back of the bike with the motor mounted in the center. I can notice the weight when I ride and kept it to only 3 packs. I have to head back for my other 3 spares after 45minutes of riding, but it beats having a bike that feels like dead weight. That’s why I really focused on a more balanced bike for my next version.

 

[dogman dan]

Is the bike for street riding? If so, then it's not the more the better on suspension, but for sure you want 80-100 mm. But put a DH bike with 150 mm of suspension on the street and pretty quick you will be preloading it down to about 100 mm of movement. On the street, the pedal bob gets to be much more of a problem since the smooth street lets the shocks get going like a pogo stick. Sorta bobbing higher each pedal stroke till it gets whacky.

Of course, a DH bike with the suspension stiffened up could always be quickly adjusted to ride on the dirt, but chances are you have the wrong tires if you have been street riding. It just depends on how the bike gets used. I do long miles on the street so my bikes get set up as either fully street or fully dirt.

Still want the triangle space too, like I said. Like a good breast, you'll appreciate it. You'll find something to carry there even if the batteries go elsewhere. I'm rebuilding my commuter today to a mongoose frame with 100mm front and back, and a nice open triangle.

 

[j-vtol]

I'm currently using a KHS Alite500 hardtail, so I don't have any tips on mounting batteries around a FS shock so far.(Go for it !) But, like other people have mentioned here, you will definitely notice a balance difference by trying to mount batteries low as possible near the center of the frame. 8)