# Is the short travel 27.5 the pariah of the mountain bike world? Looking at the Siskiu D7



## DeoreDX (Jul 28, 2007)

I've spent the last 3 months mostly riding an old 2008 26" 120mm travel Stumpjumper FSR Comp that has been modernized with a 1x10 and dropper. Never felt over biked or under biked on it and although not the fastest bike I've ridden it was just a lot of fun to ride (And light! 27.5lbs before I added the dropper and heavy tires). I'd love a modernized version (like the 26" wheels) a little longer (1116) a little slacker (68.5) with a little steeper seat (74.5) with a little more anti squat so it climbs a little better. I rebuilt the stumpjumper for my 12yo and he's finally getting big enough to ride it so he's been taking it on the trails recently and I'm back on the 29er hardtail. In a impulse yesterday I ordered a Polygon Siskiu D7 in 27.5 cause it was so damned cheap ($1699). It's a little longer (1167 v 1116), a little slacker (67 v 68.5) with a little steeper seat (75.5) and had more anti squat for better climbing so it checks all the original boxes. But now I'm having second thoughts. 1st doubt was the incredibly low bottom bracket height (325). Seems crazy low to me even in this era of low bottom bracket heights. I thought the 335 height of the Stumpjumper was low and took a while to get used too. 2nd thing I didn't like was the 15x100 axle. I don't plan on upgrading the fork but if I do that limits my choices or increases the cost to upgrade.

With the market moving away from 27.5 short travel bikes (except for our short friends) I'm beginning to wonder if I really want a short travel 650b. The most popular short travel bikes seem like they are normally 29ers. All the downcountry bikes are all 29ers. Should I be considering a mid travel 650b/140mm bike instead? Honestly seems like a lot of bike for my needs. Closer to 50 than 40 I don't hit the speeds I used to in my youth. Don't do bike parks or big chunky downhill lines. I grew up with MTBs in the 90's and learned how to go down steep grades on 26" steep head angle bikes so even the 68.5 of the FSR feels slack to me. I love difficult technical climbs and the little light stumpy was great for those. Maybe a modern short travel 29er would work too? I've read that the new breed of short travel 29ers feel more lively than those of the past but I've never ridden on one. The problem with nothing in stock locally it's hard to test ride to get a feel for the different bike sizes. At least with Bikesonline I can 14 day test ride it. Locally any FS in my 2-3k range is sold before it hits the floor so I basically to pick something and special order it. Is a short travel 27.5 a bad idea?


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## Sideknob (Jul 14, 2005)

Low BB's utterly suck anywhere there are rocks, roots or anything higher than a billiard ball. That would be my main concern.


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## genny1 (Jul 7, 2005)

I don't own a short travel 29er, but obviously folks have lots of love for them. I have liked them when I have test ridden a few. I am not much help as to that market segment.

If you do continue to consider 27.5 and the Siskiu doesn't prove to check enough boxes, my two cents fwiw is consider a used Rocky Mountain Thunderbolt. I am most familiar with 2018s (I shopped them) and 2019s (I own one), which are essentially the same. The non-BC editions are 130/130 travel, and the Ride-9 system makes them adjustable - you can play around and experiment with how slack and how low it is, which sounds like a feature you'd like. The A10, A30, and A50 are aluminum frame models with ascending specs and price tags, and then the C30, C50, C70 models are carbon with ascending specs and price tags.

Here is a link to the RM website page for the 2019 Thunderbolts.

In 2020, Rocky increased the Thunderbolt travel to 140/140 (previously only the BC editions were more than 130/130). In 2021, they made only aluminum Thunderbolts, 150/140 travel.

Availability and price may be issues. They pop up on Pinkbike buy/sell periodically, but the U.S. market in particular is not swimming in them. A used aluminum model should be in the $2K to $3K price range. The carbon probably $3K and up used. And unless you get really lucky locally, you won't likely be able to buy before you try.

I came from a 26" bike too, and I like the 27.5 wheel size, the 130/130 short (shortish?) travel, and the Ride-9 adjustability. Maybe a used 2018 or 2019 might work for you. Again, just my two cents. Good luck!


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## DeoreDX (Jul 28, 2007)

Still waiting on my Siskiu D7 to ship. In the mean time I've been comparing the geometry of the Siskiu to other bikes and modeled the frame up in the bike geometry calulator and I have come to the opinion that the frame is actually designed for a longer fork than the 120mm Recon that is on it. The 120mm Recon has a very short A2C measurement of 506mm. The 130mm Recon is +18mm taller at 524mm and throw that on there and suddenly the 67 head tube angle is 66, 75.5 seat tube is 75, and the bottom bracket is around 330mm instead of 324. 130-140mm fork will really be the sweet spot for this frame. I'm guessing they had a last minute spec change to the 120mm Recon (adjustable 100-120mm) since it's cheaper than the 130 (adjustable from 130-150mm) to hit a price point. Fork and a 203mm rotor are really the only 2 upgrades I would ever contemplate doing outside of moving my 165mm cranks to the bike. I measured my stumpjumper and I'm at 327mm BB height so I guess I'm already used to a really low BB so I think I'll be happy with the D7.


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## genny1 (Jul 7, 2005)

Excellent, enjoy!!!


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## mi26r (Nov 10, 2012)

DeoreDX said:


> Still waiting on my Siskiu D7 to ship. In the mean time I've been comparing the geometry of the Siskiu to other bikes and modeled the frame up in the bike geometry calulator and I have come to the opinion that the frame is actually designed for a longer fork than the 120mm Recon that is on it. The 120mm Recon has a very short A2C measurement of 506mm. The 130mm Recon is +18mm taller at 524mm and throw that on there and suddenly the 67 head tube angle is 66, 75.5 seat tube is 75, and the bottom bracket is around 330mm instead of 324. 130-140mm fork will really be the sweet spot for this frame. I'm guessing they had a last minute spec change to the 120mm Recon (adjustable 100-120mm) since it's cheaper than the 130 (adjustable from 130-150mm) to hit a price point. Fork and a 203mm rotor are really the only 2 upgrades I would ever contemplate doing outside of moving my 165mm cranks to the bike. I measured my stumpjumper and I'm at 327mm BB height so I guess I'm already used to a really low BB so I think I'll be happy with the D7.


What boost fork would you get in the 130-140mm range?

I have the D7 as well and eventually want to upgrade the fork. the freewheel came apart on me, and waiting for my new wheels to arrive. I bought them in a set, so I'll have the front boost when the time comes.

thanks!


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## ehayes (Jun 25, 2019)

The Rocky Mountain Thunderbolt is a good suggestion.

I ride a V3 Santa Cruz 5010 and love it (130mm 27.5"). The 5010 and Thunderbolt are very similar. I would likely have bought a Thunderbolt if I could have demo'd it. It was cheaper/lighter for similar specs, though my 5010 has been amazing and bombproof.

I am mid-40s and learned to ride on 26" Konas in the late 90s, early 2000s. Any of the modern bikes I demo'd two years ago prior to buying the 5010 were ridiculously capable (although most were much heavier than I was used to).

The bottom bracket on my 5010 is 330mm (in the lower of the two flip chips settings, which I usually ride in). I do get pedal strikes at times (and worse, a chainring hit going over boulders a couple times a year), but I accept them for the low center of gravity. I could use the higher flip chip setting if it I wanted for ~5mm more height.

I have recently rented 29ers while traveling, and have not real complaints. I do notice they are slightly less agile though probably faster and more stable.


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## TylerVernon (Nov 10, 2019)

I didn't see you mention the Mojo 3 or 4.


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## stripes (Sep 6, 2016)

TylerVernon said:


> I didn't see you mention the Mojo 3 or 4.


Definitely should be in the list. The short list:
ibis Mojo
SC 5010
GG Shred Dogg

There is definitely a need for a short travel 27.5, and it's frustrating that the industry is moving away from it. I'm not a fan of 29in wheels, and it would be nice to have more short travel options and even more hardtails (Chromag still makes these I think) in the smaller wheel size.


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## wishiwasbiking (Nov 10, 2019)

Two other bikes that I was looking at when looking at a shorter travel 27.5 were the yeti sb140 and the transition scout, although these two bikes blur the line between short travel and bigger bikes.


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## DeoreDX (Jul 28, 2007)

I've had the Siskiu for about a month and it's been everything I wanted it to be. Very poppy. Easy to pump. Just enough travel to feel safe and comfortable but not so much that you feel insulated and isolated from the trail. Big roots or rocks I can just mash over on a 140mm 29er I now have to give a little body english to maintain speed. A more engaged experience of not being over biked is what I was after without having to use my hard tail and this 120mm 27.5 feels like it strikes a good balance for me.

For the Polygon Siskiu itself it wouldn't be my first choice but the value is definitely there. Set it beside a Kona or Orbea and the fit and finish of the fram which looks nice from afar just isn't quite as nice up close. Outside of cosmetics the bike itself is great. A non-boost front wheel matched to a boost rear is the biggest complaint for the spec of the bike. Makes replacing the heavy 2156g wheelset a big PITA. It at least came with 30mm internal width rims which was a pleasant surprise. The bottom bracket is also extremely low at 326mm. First thing I did was put 165mm cranks on as that's my prefered crank length for knee pain. I have an old Fox 36 I was able to adjust the travel to test different fork lengths and found I like the way the bike rides raising the front end up a bit. 130-140mm and run a bit higher pressure in the rear to keep it from sagging back. Currently have my 36 set at 130mm and the bike feels well balanced. The 150mm dropper with the absurdly long seat tube was about ~10mm too high for me. I had a 125mm PNW Loam I was able to steal off another bike which knocked a bit of weight and made for a better length.

For the weight weinies the bike came in a 33lbs 7oz from the factory. Switching to Tubeless, changing pedals, XT cranks, and the dropper put it at 31lbs 15oz. Bike rides great. The Fox 36 is overkill for this bike but I guess it can stay for the time being. Fork rides fine and it would cost a lot of money just to get a slightly lighter fork. Only thing I would want to change on it now are the wheels and a 34t front chainring. 32t with a 51t rear is way undergeared for a 27.5. I have changed the decals on my fork to better match the bike but this was the only picture I have of the bike with the Fox on it.


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